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302 Cards in this Set
- Front
- Back
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What does the development of embryonic structures into male and female reproductive organs and external genitalia depend on?
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fetal hormone production
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What are pseudoautosomal regions?
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homologous regions at the ends of X and Y chromosomes that are not inactivated during X chromosome inactivation
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Where is the SRY gene located?
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Y chromosome
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What is the function of the SRY gene?
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transcription factor that promotes differentiation of an indifferent gonad into a testis
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What gene can be translocated on the X chr. because of its proximity to the pseudoautosomal region?
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SRY gene
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During X inactivation is everything on that X chr. inactivated?
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everything but the pseudoautosomal region is inactivated
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What is a Barr body?
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inactivated chr. that appears as an X chromatin body
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How do you calculate the number of Barr bodies?
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number of X chr. minus 1
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What does XIST stand for and what is its function?
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X inactive specific transcript; encodes a large RNA that coats the X chr. and facilitates inactivation of genes on the X chr.
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What is meiotic nondisjunction?
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when homologous chr. fail to separate during meiosis, resulting in gametes that either gain or lose chr.
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What can nondisjunctions occuring in early mitotic divisions produce?
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a mosaic pattern
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What is a mosaic pattern?
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two or more populations of cells that have a different complement of chr.
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How do you calculate the number of Barr bodies?
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number of X chr. minus 1
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What does XIST stand for and what is its function?
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X inactive specific transcript; encodes a large RNA that coats the X chr. and facilitates inactivation of genes on the X chr.
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What is meiotic nondisjunction?
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when homologous chr. fail to separate during meiosis, resulting in gametes that either gain or lose chr.
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What can nondisjunctions occuring in early mitotic divisions produce?
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a mosaic pattern
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What is a mosaic pattern?
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two or more populations of cells that have a different complement of chr.
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What is 47 XXY?
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Kleinfelter syndrome
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What is 47 XXX?
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no known syndrome
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What is 45 XO?
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Turner syndrome
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What is 45 YO?
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lethal
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What determines gonadal differentiation?
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the chr. content of the tissue
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Differentiation of the reproductive tract and external genitalia depends upon?
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fetal hormone production
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During what wk do the primordial germ cells migrate from the yolk sac endoderm to the indifferent gonad?
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5th and 6th week
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What do the germ cells that migrate during the 5th and 6th week become?
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spermatogonia or oogonia
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What is required for an indifferent gonad to develop into a testis?
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SRY gene
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What is the first sign of testis differentiation?
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appearance of Sertoli cells in the medulla
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What cells come into the medulla after the Sertoli cells appear?
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Leydig cells
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What cells participate in the formation of testicular cords that later become the seminiferous tubules?
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Sertoli cells
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Is the presence of germ cells required for seminiferous tubule development?
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no
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When does the meiosis of germ cells begin in males?
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puberty
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What can alter the process of testicular development?
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the presence of more that one X chr.
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What happens to the testes in an adult male that has multiple X chr.? What is this condition called?
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small, atrophic, devoid of sperm; Kleinfelter syndrome
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What is Kleinfelter syndrome most commonly caused by?
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meiotic nondisjunction
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What 3 things are required for the differention of an ovary?
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1)invasion of the cortex by the primordial germ cells
2)reactivation of the inactivated X chr. in the germ cells 3)absence of the SRY gene |
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What happens about the 8th wk of gestation in a female fetus in regards to oogonia? What are these cells now called?
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some of the oogonia leave the pool of proliferating cells and enter meiosis; primary oocytes
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Where is meiosis arrested in primary oocytes?
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prophase of the first meiotic division
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During what weeks do seminiferous tubules develop?
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6-7
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During what weeks do Leydig cells develop and secrete testosterone?
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8-9
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When does oogenesis begin in the ovary?
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wk 11-12
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When does the primordial follicle form in the ovary?
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wk 13
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When are the preantral follicles present?
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wk 26
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If the mullerian ducts exist, what do they develop into?
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fallopian tubes, uterus, cervix, and upper third of vagina
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If the wolffian ducts exist, what do they develop into?
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epididymis, vas deferns, seminal vesicles, and ejaculatory ducts
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What happens to the wolffian ducts in the absence of androgen stimulation?
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undergo regression
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What causes the mullerian ducts to undergo apoptosis? Is this a time sensitive event?
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Sertoli cells secrete AMH that binds to receptors in the mullerian duct; mullerian ducts lose their responsiveness to AMH by the end of the 8th wk
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What does wolffian duct differentiation occur in response to?
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testosterone released by the fetal Leydig cells
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What stimulates testosterone production by the fetal testes?
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hCG
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In the absence of hormone stimulation, what internal genital structures develop?
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female
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What are the effects of female sex hormones on the fetus?
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none have been observed
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What causes the differentiation of external genitalia along male lines?
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DHT (dihydrotestosterone)
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What enzyme converts testosterone to DHT?
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5 alpha-reductase
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What causes the external genitalia to develop along female line?
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the absence of androgen stimulation
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What does the genital tubercle give rise to in males and females?
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glans penis in males and clitoris in females
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What does the genital swelling give rise to in males and females?
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scrotum in males and labia majora in females
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What do the genital folds give rise to in males and females?
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ventral folds of penis in males and labia minora in females
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When is differentiation of the male external genitalia complete?
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wk 14
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What happens in a normal 46XY individual with complete androgen resistance?
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testes capable of secreting androgens will be present in the abdominal cavity, male and female internal genital tracts will be absent, and the external genitalia and secondary sex characteristics will be female
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What happens to a fetus exposed in utero to excessive amounts of androgens?
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can induce varying degrees of virilization of the external genitalia depending on the time of the initial exposure
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What happens in genetic males who have a 5 alpha-reductase enzyme deficiency?
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male internal reproductive tract, small penis w/o an orifice, female external genitalia, and virilization will occur at puberty
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What is the final step of sexual differentiation in a male fetus?
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descent of the testes
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What hormone is believed to play a part in testicular descent?
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testosterone
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What is cryptorchidism?
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when one or both testes fail to descend
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During what time of development do the testes normally descend into the scrotum?
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between 25-32 wks
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What is another name for seminiferous tubule dysgenesis?
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Kleinfelter syndrome
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What is another name for gonadal dysgenesis?
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Turner syndrome
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What does 46XY DSD refer to?
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defective virilization of a 46XY embryo with normal testes; external genitalia may be ambiguous or female, and internal genital tract may be poorly developed or absent
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What are the 3 things that can cause an individual to be 46XY DSD?
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1)enzyme deficit in the testosterone biosynthetic pathway
2)androgen receptor defect 3)5 alpha reductase deficiency |
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What can cause the syndrome of persistant Mullerian ducts to occur? What would you see in this patient?
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when a normal male can't synthesize AMH or has a defective AMH receptor; mullerian duct derivatives are present in inguinal hernias and the testes often fail to descend
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What does 46XX DSD refer to?
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phenotypic female that has normal ovaries and mullerian duct derivatives, but ambiguous external genitalia
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What is the major cause of 46XX DSD?
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exposure to excessive androgens in utero
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What is the principal manifestation of androgen exposure after 12wks of gestation?
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clitoral hypertrophy
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When does spermatogenesis begin and where does it occur?
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begins at puberty in the seminiferous tubules
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Where does steroid hormone synthesis occur in males?
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Leydig cells which are located in the CT of the seminiferous tubules
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By mid-gestation what appears to affect testosterone secretion in male fetuses?
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fetal pituitary gonadotropins
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What is the major androgen produced by the testes?
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testosterone
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When do the adrenal glands begin producing androgens?
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about yr 8 of life
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What are the 3 ways testosterone can be transported in the blood?
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1)2-3% is free
2)40-60% is bound to sex steroid-binding globulin 3)rest is loosely bound to albumin and other plasma proteins |
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What enzyme metabolizes testosterone to estradiol in some tissues?
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aromatase
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What are the 3 areas where aromatization of testosterone occurs?
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certain CNS nuclei, Leydig and Sertoli cells, adipose tissue
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Where does inactivation of testosterone occur? Are the excretory metabolites active or inactive?
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occurs in the liver; inactive
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What enhances the solubility of excretory metabolites in the urine?
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conjugation with sulfate or glucuronic acid
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Are levels of testosterone in males high or low during childhood?
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low
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The rise in testosterone at puberty correlates with a rise in what plasma hormone conc.?
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LH
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What hormone promotes androgen biosynthesis in Leydig cells? What is the mechanism?
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LH; cAMP-dependent mechanism
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Are there multiple or single receptors for androgens?
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a single receptor for all androgens
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What forms of testosterone do the androgen receptors bind?
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both testosterone and DHT, but has a greater affinity for DHT
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Where is the androgen receptor located in the cell?
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nucleus
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When the hormone binding site for androgens is unoccupied what happens to the receptor?
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bound to a complex of heat shock proteins
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The androgen receptor doesn't bind to DNA unless?
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the hormone is bound to its appropriate binding site on the receptor
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What happens to the androgen receptor when it binds with an androgen?
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dissociates from the heat shock proteins and then forms a homodimer with another receptor molecule
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Hormone-occupied receptor dimers recognize and bind to target genes by means of a specific DNA sequence called? Where is it located?
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a hormone response element; located in the regulatory region of the target gene
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What do steroid hormone receptors function as?
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ligand-activated transcription factors
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In hormone-dependent activation of gene transcription, steroid hormone-bound receptor dimers recruit?
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complex of coactivator proteins
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What are the 4 functions of coactivator proteins?
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1)possess HAT activity which lessens the interactions between DNA and histones so that transcriptional regulatory proteins can access the DNA in target genes
2)promote DNA unwinding 3)recruit other coactivator proteins 4)interact with and enhance activity of general transcription factors in promoting gene transcription |
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In hormone-dependent negative regulation of gene transcription, steroid hormone-bound receptor dimers recruit?
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corepressor proteins and HDAT
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What happens with the binding of a receptor antagonist to the steroid receptor?
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induces a conformational change in the receptor that may prevent coactivators from binding and/or favor corepressor binding to the steroid hormone receptor
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At puberty in males, what two things do androgens promote?
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growth and maturation of the reproductive tract; development of male secondary sex characteristics
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When the hormone binding site for androgens is unoccupied what happens to the receptor?
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bound to a complex of heat shock proteins
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The androgen receptor doesn't bind to DNA unless?
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the hormone is bound to its appropriate binding site on the receptor
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What happens to the androgen receptor when it binds with an androgen?
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dissociates from the heat shock proteins and then forms a homodimer with another receptor molecule
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Hormone-occupied receptor dimers recognize and bind to target genes by means of a specific DNA sequence called? Where is it located?
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a hormone response element; located in the regulatory region of the target gene
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What do steroid hormone receptors function as?
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ligand-activated transcription factors
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At puberty, what two things do androgens promote?
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growth and maturation of reproductive structures; development of secondary male sex characteristics
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Are androgens catabolic or anabolic?
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anabolic
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What hormones regulate spermatogenesis?
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androgens
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What are the effects of DHEA and androstenedione on the androgen receptor?
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weak and even negligible effects because of their very low affinity for the receptor
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What hormones stimulate erythropoietin?
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androgens; this inc the hematocrit
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What three effects do androgens have on bone growth and formation?
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1)stimulate GH release
2)stimulate pubertal growth spurt 3)promote closure of epiphyseal plate |
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What cells line the basal lamina of the seminiferous tubules?
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Sertoli cells
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What are the principal functions of the Sertoli cells?
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nurture developing germ cells and provide an environment for germ cell differentiation into mature spermatozoa
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What divides the seminiferous tubules into two functional compartments?
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tight junctions between adjacent Sertoli cells
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Are spermatogonia located at the basal compartment or adluminal compartment?
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basal
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Are the spermatocytes and more mature cells found at the basal compartment or adluminal compartment?
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adluminal
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What forms the blood-testes barrier?
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tight junctions between adjacent Sertoli cells
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Are spermatogonia located at the basal compartment or adluminal compartment of the seminiferous tubules?
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basal compartment
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Are spermatocytes found at the basal compartment or adluminal comparment of the seminiferous tubules?
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adluminal
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What is the function of the blood-testes barrier?
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limits transfer of interstitial fluid contents into the lumen of the seminiferous tubules and vice versa; may also serve to prevent the formation of autoantibodies against against the highly differentiated sperm cells
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What hormone binds to receptors on Sertoli cells? Various responses are elicited via what mechanism?
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FSH; cAMP-dependent mechanisms
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Sertoli cells secrete proteins belonging to what family?
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transforming growth factor beta family
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What is the funtion of StAR?
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moves cholesterol into the mitochondria
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What stimulates FSH? Inhibits FSH?
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FSH, testosterone
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What hormones are included in the transforming growth factor beta family?
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AMH, activins, inhibins
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What hormones are included in the transforming growth factor beta family?
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AMH, activins, inhibins
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What is the purpose of ABP secreted by the Sertoli cells into the seminiferous tubules?
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keeps testosterone levels elevated in the seminiferous tubules and epididymis
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What 2 hormones stimulate ABP production by the Sertoli cells?
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FSH and testosterone
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What can be measured to assess Sertoli cell function?
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ABP levels
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What hormone promotes the regression of the mullerian ducts in the male fetus?
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AMH
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When do circulating AMH levels peak? When do they fall?
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peak during prepuberty; fall as testosterone levels rise
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What are the two subunits of the AMH receptor?
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1)primary specific receptor
2)secondary signal transducing subunit |
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What happens to the primary specific receptor subunit when it binds AMH?
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forms a complex with and phosphorylates the signal transducing subunit; this activated receptor complex phosphorylates Smad proteins which in turn bind Smad 4; resultant complex is translocated to the nucleus where it induces the transcription of genes that promote apoptosis of the mullerian ducts
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What is the most important inhibin secreted by the testes?
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Inhibin B
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What 2 hormones stimulate inhibin B production by the Sertoli cells?
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FSH and testosterone
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Does inhibin B have an effect on LH release?
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no
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Inhibin B blocks what hormones release?
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FSH
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What hormone may play a stimulatory role in spermatogenesis?
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estradiol
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What is the effect of inhibin on testosterone release?
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inc testosterone release by Leydig cells
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What are the 3 distinct phases of spermatogenesis?
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1)mitosis to inc the number of spermatogonia
2)meiosis to provide haploid spermatids 3)spermiogenesis to transform immature spermatids to mature spermatozoa |
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What are the four components of spermiogenesis?
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condensation of chromatin, reduction in the amount of cytoplasm w/in the cell, the development of a flagellum, and the formation of an acrosome
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The transformation of spermatogonia into spermatoza occurs in cycles lasting about?
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64 days
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During spermatogenesis, the developing sperm cells are embedded into the cytoplasm of what cells?
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Sertoli cells
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What happens during spermiation?
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mature spermatids are released from the Sertoli cells
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Where do spermatozoa undergo further maturation after being released from the Sertoli cells? What important thing happens here?
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in the epididymis; remain here for about 2 wks; acquire the capacity to be motile
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In the adult, normal spermatogenesis requires what 2 things?
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1)functional Sertoli cells
2)intact hypothalamic-pititary-gonadal axis |
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How must GnRH be delivered to the pituitary in order for FSH and LH to be secreted appropriately?
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pulsatile fashion at regular intervals
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What hormone is required for the maintenance of normal levels of sperm production and sperm cell maturation?
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FSH
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What hormone promotes Sertoli cell maturation?
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FSH
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What 3 cells have testosterone receptors?
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Sertoli cells, Leydig cells, peritubular cells
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Do Sertoli cells have LH receptors?
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no
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How does LH promote spermatogenesis?
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because it stimulates testosterone release from Leydig cells
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What regulates the secretion of FSH and LH?
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GnRH
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What is Kallman Syndrome?
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form of hypogonadism caused by a failure of GnRH secreting cells to migrate from the olfactory bulb to the hypothalamus during development
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What occurs in male pts with Kallman syndrome?
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have low circulating levels of gonadotropins, symptoms of androgen deficiency that become apparent at puberty, and arrested spermatogenesis; can also occur in women
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Where is GnRH produced?
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arcuate nucleus and preoptic area of the hypothalamus
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What kind of receptor does GnRH bind to?
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G protein coupled receptor
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What second messenger mediates GnRH release?
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via Ca++ and PIP2
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Are gonadotropins released in secretory bursts or continuously?
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secretory bursts
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The release of pituitary gonadotropins is a function of what 2 things?
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both the conc and release pattern of GnRH
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What causes "functional castration?"
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continuous exposure of the gonadotroph to GnRH which suppresses gonadotroph secretory activity
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The onset of puberty is characterized by a sleep-associated surge in what hormone?
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LH
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What hormone in males is associated with the anatomical and physiological changes normally associated with puberty?
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testosterone
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What are the 4 hypothalamic and pituitary changes associated w/ puberty?
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1)dec in the negative feedback effects of testosterone
2)inc in amplitude and frequency of GnRH release 3)inc in sensitivity of gonadotropes to GnRH 4)inc secretion of FSH and LH |
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What hormone inhibits the hypothalamic pulse generator thereby reducing GnRH pulse frequency?
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testosterone
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What two things initiate the erectile response?
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tactile (LMN reflex) or psychic (mediated over corticospinal pathways)
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How are afferent tactile stimuli transmitted to the sacral segements of the spinal cord?
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via the pudendal nerve
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Are efferent PNS fibers to the penile arteries and sinusoids vasodilatory and vasoconstrictive? What do they secrete?
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vasodilatory; VIP and NO
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How does NO work?
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binds to and activates the soluble form of guanylyl cyclase; resultant rise in cGMP levels leads to SM relaxation and vasodilation
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What drugs can be used to treat erectile dsyfunction?
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cGMP-specific phosphodiesterase inhibitors
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What glands secrete mucus during sexual stimulation? Is this response mediated via PNS or SNS?
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urethral and bulbourethral glands; PNS
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What is emission? What muscles does it involve?
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movement of semen into the proximal part of the urethra; involves the coordinated rhythmic contractions of SM of the vas deferens, the prostate, and the seminal vesicles
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What is emission? What muscles does it involve?
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movement of semen into the proximal part of the urethra; involves the coordinated rhythmic contractions of SM of the vas deferens, the prostate, and the seminal vesicles
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What neurons mediate emission? What neurotransmitter is released?
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sympathetic neurons in the upper lumbar region of the spinal cord; NE released onto alpha-1 adrenergic receptors
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What prevents retrograde ejaculation?
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sympathetic signals which promote the constriction of the internal sphincter of the bladder
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Filling the urethra with semen elicits sensory signals that are transmitted to what portion of the spinal cord? By what nerve?
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sacral portion; pudendal nerve
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What are the 3 systemic changes associated with the male sexual response?
|
inc rate of respiration, inc HR, inc BP; these responses reach a peak during ejaculation
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What are the 3 clinical manifestations of testicular dsyfunction?
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infertility, dec libido, lack of development of secondary sexual characteristics
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What are some of the clinical features of androgen deficiency that are present at the age of puberty?
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abnormal skeletal proportions, gynecomastia, sparse pubic, axillary and facial hair, high pitched voice, infantile genitalia, and poorly developed musculature
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What is gynecomastia?
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hypertrophy of non-fatty tissue of breasts
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Does estradiol stimulate or inhibit the growth of breast tissue?
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stimulate
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Does testosterone stimulate or inhibit the growth of breast tissue?
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inhibit
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What does primary hypogonadism in males refer to?
|
primary testicular failure
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What is the most common karyotype for Kleinfelter syndrome?
|
XXY
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What 2 things determine the severity of Kleinfelter syndrome in a pt?
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number of excess chromosomes and the number of stem cell lines having excess X chromosomes
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What happens to the seminiferous tubules in a pt with Kleinfelter syndrome?
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fibrotic and hylanized
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Are FSH and LH levels in a pt with Kleinfelter syndrome low, normal, or high?
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high
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Are testosterone levels in a pt with Kleinfelter syndrome low, normal, or high?
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low to normal
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Are estradiol levels in a pt with Kleinfelter syndrome low, normal, or high?
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high due to inc peripheral conversion of testosterone to estradiol
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What 2 non-genetic things can cause Kleinfelter syndrome?
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orchitis, irradiation
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What is orchitis? What cells are more severely affected?
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inflammation of the testes usually secondary to mumps; seminiferous tubules
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What is a characteristic of secondary hypogonadism?
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impaired gonadotropin secretion
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What can cause secondary hypogonadism?
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hypopituitarism
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What is the second most common reproductive disorder in males?
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Kallmann syndrome
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What syndrome in males is often associated with a defective sense of smell?
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Kallmann syndrome
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In males, exposure to what other hormone besides estrogen will promote breast growth?
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prolactin
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What is the most potent and biologically active form of estrogen?
|
estradiol (E2)
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What is the principal post-menopausal estrogen?
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estrone (E1)
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Which estrogen is derived primarily from peripheral conversion?
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estrone (E1)
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Which estrogen is produced by the placenta during pregnancy?
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estriol (E3)
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In the non-pregnant adult, what is the primary source of estrogens?
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ovaries
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How is estrone formed?
|
peripheral conversion of estradiol and androstenedione
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What is the primary androgen secreted by the thecal cells?
|
androstenedione
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What does the thecal cell use to synthesize steroid hormones?
|
since they are close in proximity to blood vessels, they have access to a steady supply of LDL cholesterol
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Why aren't thecal cells able to convert androgens to estrogens?
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they don't possess aromatase activity
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What is the purpose of the androgens made by the thecal cells?
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androstenedione diffuses to the granulosa cell where it is utilized
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Do granulosa cells have access to LDL cholesterol? What enzyme do they lack?
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no;lack 17-alpha hydroxylase and are therefore unable to convert pregnenolone and progesterone to androgens
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What enzyme do granulosa cells have high concentrations of? What does this enzyme allow them to do?
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aromatase; able to convert androstenedione made by the thecal cells into estradiol
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What is the primary secretory product of the granulosa cells?
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estradiol
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What enzyme do granulosa cells express that favors the conversion of estrone to estradiol?
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isoform of 17-beta hydroxysteroid dehydrogenase
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What hormone regulates the activity of the thecal cells?
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LH
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What hormone regulates the activity of the granulosa cells?
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FSH
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What second messenger system is active in both the thecal cells and granulosa cells?
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cAMP signaling pathway
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What are the 2 major ovarian progestins?
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progesterone and 17-alpha hydroxyprogesterone
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What is the principal source of progesterone in the non-pregnant adult?
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corpus luteum
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What is the principal circulating androgen in women?
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testosterone
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What are the 3 phases of the reproductive cycle in non-pregnant women?
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follicular, ovulatory, luteal
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When does the follicular phase begin? Is it variable?
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begins with the onset of menstrual bleeding; yes
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What does the follicular phase correspond to?
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proliferative phase of the endometrial cycle
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Is the luteal phase constant?
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yes 13-14 days
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What does the luteal phase correspond to?
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secretory phase of the endometrial cycle
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When does the luteal phase end?
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ends with the onset of next menses
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What happens during the follicular phase?
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preovulatory follicle develops w/in the ovary
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What is the primary hormone influencing changes in the female reproductive tract during the follicular phase?
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estradiol
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The follicular phase corresponds to what phases of the endometrial cycle?
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menstrual and proliferative phases
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What hormones are secreted during the luteal phase?
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progesterone and estradiol
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The luteal phase corresponds to what phase of the endometrial cycle?
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secretory phase
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What are primordial follicles?
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primary oocyte surrounded by a single layer of poorly differentiated granulosa cells
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What is arrested in the primary oocyte?
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meiosis
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When does primordial follicle formation begin?
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in the fetus and is complete by 6mos of age
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What are the most abundant follicles in a woman?
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primordial follicles
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What is the mechanism for initiating the growth of primordial follicles?
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occurs in the absence of gonadotropin stimulation and involves intraovarian signals
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What is atresia? What cells does atresia mainly affect?
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form of programmed cell death; oocytes and granulosa cells
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Which hormone opposes apoptosis in females?
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FSH
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What are 3 factors that promote atresia?
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TNF alpha, androgens, IL-6
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What is a primordial cell called when it leaves the pool of inactive follicles, enlarges, and the zona pellucida forms around it?
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a primary follicle
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As the secondary follicle is formed, the granulosa cells acquire receptors for?
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FSH and estrogens
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How do the granulosa cells become functionally coupled as the secondary follicle develops?
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by gap junctions to adjacent cells and the oocyte
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What hormone receptors do interstitial cells begin to express as the secondary follicle develops?
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LH
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Is follicular growth from the primordial follicle to the secondary follicle gonadotropin independent or dependent?
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independent
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In the absence of FSH, what happens to the maturing follicle?
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stops growing and undergoes atresia
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When is the dominant follicle selected?
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during the early follicular phase of the current cycle
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What characterizes the growth of the dominant follicle?
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granulosa cell proliferation and an expansion of the antrum
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How many days after a follicle is selected does ovulation occur?
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10-14 days
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Why do non-dominant follicles undergo atresia?
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due to low FSH levels because of negative feedback
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What is the role of FSH in the selection process of the dominant follicle?
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FSH stimulates granulosa cell proliferation and estradiol synthesis; in addition these induce FSH receptor synthesis which enhances the sensitivity of the follicle to FSH stimulation
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How does estradiol affect FSH release? Why is this important?
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has a negative feedback effect on FSH release by the anterior pituitary; how the dominant follicle inhibits the development of less mature follicles in the cohort
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What happens as circulating levels of FSH fall below the level necessary to promote follicular maturation?
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all but the dominant follicles undergo atresia
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What is one of the most characteristic features of atretic follicles?
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absence of FSH in their follicular fluid
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What is produced by the dominant follicle that suppresses FSH secretion?
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estradiol
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What are the 5 things that allow the dominant follicle to grow in the presence of declining FSH levels?
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1)FSH receptors are upregulated so it becomes more sensitive to FSH
2)produces other GFs 3)has FSH induced expression of LH receptors 4)FSH accumulates in the antral fluid 5)FSH promotes the expression of vascular endothelial GF which may help the preferential delivery of FSH to the dominant follicle |
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Why is the expression of LH receptors essential during follicular development?
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in order for the cells to respond to the LH surge that induces ovulation
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Ovulation is induced by an abrupt surge in?
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LH
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What causes the LH surge that induces ovulation?
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result of the positive feedback effect of estradiol on the pituitary and hypothalamus
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What two genes can you block to prevent ovulation?
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COX-2 and progesterone receptor
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What hormone induces the expression of prostaglandins?
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LH
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What hormone in the female reinitiates meiosis?
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LH
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What does the corpus luteum form from?
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remnants of the ruptured follicle
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Do the granulosa-lutein cells become vascularized?
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yes, which allows them to obtain cholesterol from circulating LDL
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What receptors do the granulosa-lutein cells express?
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LH and FSH; also continue to synthesize the aromatase enzyme
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What hormone produces the enzyme to promote the conversion of cholesterol to progesterone?
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LH
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Estrogen production by the corpus luteum requires?
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presence of both lutein cells; androgens synthesized by the thecal lutein cells in response to LH stimulation are converted to estrogens by the granulosa lutein cells
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If pregnancy doesn't occur by day ___, the corpus luteum begins to?
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9; undergo luteolysis
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If pregnancy occurs, what maintains the corpus luteum?
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chorionic gonadotropin
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What helps bring about luteolysis?
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the decline in LH production due to the negative feedback effects of estrogen and progesterone
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The LH surge that triggers ovulation is timed to coincide with?
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the maturation of the dominant follicle which is growing rapidly and producing large amounts of estradiol
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Estradiol and progesterone act on both the? Inhibins act only on the?
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pituitary and hypothalamus; pituitary
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The increase in what hormone is critical for the cyclic recruiting of follicles for the next cycle?
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FSH
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At the start of the follicular phase, what hormone levels are increasing? What hormone's level is constant?
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FSH; LH
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During the early follicular phase, what hormone promotes granulosa cell proliferation?
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FSH
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During the early follicular phase, what hormones stimulate estradiol synthesis?
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FSH and LH
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During the late follicular phase, what hormone rapidly increases? What does this rising hormone do?
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estradiol; acts on the hypothalamus to increase GnRH pulse generator frequency and on the pituitary to increase the sensitivity of the gonadotropes to GnRH stimulation
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What hormone increases during the luteal phase?
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LH
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What are secretory products of the corpus luteum?
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progesterone, inhibin A, and estradiol
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What can be used to assess FSH-mediated granulosa cell fx?
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circulating levels of inhibin B
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What can be used to assess LH-mediated corpus luteum fx?
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circulating levels of inhibin A
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What layer of the uterus is involved with regeneration after menstruation?
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the lower third - stratum basalis
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What layers of the uterus are strongly influenced by ovarian hormones?
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upper two thirds - stratum functionalis
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When do proliferative changes in the uterus begin? What hormone level is increasing?
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several days after the start of the follicular phase of the ovarian cycle; estrogen
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What is the principal action of estradiol on the uterus? What is this due to?
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to restore the endometrial lining; estradiol-mediated production of GFs by stromal cells
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What are some other effects of estradiol besides restoring the endometrial lining?
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induces growth of uterine glands and promotes the development and elongation of spiral arteries
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What hormone upregulates progesterone receptors for endometrial differentiation?
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estradiol
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The secretory phase of the uterine cycle coincides with what phase of the ovarian cycle?
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luteal phase
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During the luteal phase, what two hormones are being secreted?
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FSH and LH
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What hormone inhibits uterine epithelial cell proliferation?
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progesterone
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What hormone downregulates the estrogen receptor and increases the expression of enzymes that degrade and inactivate estradiol?
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progesterone
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What are the two main functions of progesterone?
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promote the differentiation of the endometrium and enhance its secretory capacity
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What is the net effect of progesterone-induced changes in the uterus?
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to provide nutrients for the unattached embryo and to prepare the endometrium for implantation and pregnancy
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If implantation of an embryo does not occur, what happens to the uterus?
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enters the menstrual phase
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What characterizes the menstrual phase of the uterus?
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endometrial ischemia, tissue necrosis, and the shedding of the endometrium
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The sudden drop in the levels of what two hormones lead to the onset of menses?
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estrogen and progesterone
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What is the vasomotor response of the spiral arteries? What induces this?
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when the vessels undergo progressive rhythmic contractions and relaxations during the menstrual phase of the uterus; prostaglandins
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At puberty, what 3 things do estrogens promote?
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pubertal growth spurt, breast development, growth and maturation of the female reproductive tract
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What hormone in women has been shown to inhibit the response to vascular injury and prevent atheroslerosis?
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estrogen
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What do the estrogen receptors (ER alpha and beta) act as?
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ligand-activated transcription factors
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What hormone is a potent vasodilator compound?
|
estradiol
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Does the activation of NO by estrogens require gene transcription?
|
No; works through signal transduction pathway involving a tyrosine kinase or MAP kinase
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What is the average age of onset for menopause?
|
51
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What hormone level decreases with menopause?
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estrogen
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What hormone levels increase with menopause?
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FSH, LH, GnRH
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Menopause causes?
|
H-hot flashes
A,V-atrophy of ovaries and vagina O-osteoporosis C-coronary artery disease |
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What does menopause actually refer to?
|
cessation of the menstrual cycles resulting from a decline in the supply of functional follicles
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LH is released in what type of pattern during puberty?
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nocturnal
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Gonadotropin is released in what type of pattern during the reproductive years?
|
cyclic pattern
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