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84 Cards in this Set

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3 Component organs of a Reproductive System:
1. Gonads
2. Reproductive Ducts
3. External genitalia
2 Processes involving Gonads:
-Gamete production
-Steroid hormone production
2 Processes involving Reproductive Ducts:
-Gamete transport
-Embryo nurturing
2 Processes involving External Genitalia:
-Gamete delivery/reception
2 steps in establishing sex:
1. Sex determination (genetic sex)
2. Sex differentiation (phenotypic sex)
3 Cell types in both Female and Male Gonads:
-Germ cells
-Supporting cells
-Interstitial cells
What are Germ cells derived from?
Primordial germ cells in the yolk sac
What are the supporting cells in
-Males
-Females
Males: Sertoli cells
Females: Granulosa/Follicle cells
What are the interstitial cells in males vs females?
Males: Leydig
Females: Theca
What do the interstitial cells do?
Produce Steroid Hormones - Androgens or Estrogen
What DETERMINES Sex?
Fertilization - whether the egg is XX or XY
What causes sex DIFFERENTIATION?
Genetic and Epigenetic Factors
-Hormones
-Environmental factors
What 2 hormones are mainly responsible for sex differentiation?
-Androgens
-Mullerian inhibitory substance
What does Androgen do?
Influences differentiation in the male direction by MAINTAINING THE MESONEPHRIC DUCT
What does MIS do?
Promotes regression of the female Paramesonephric Ducts (PMD) by inducing apoptosis.
What in the Brain also plays a role in sex differentiation?
Gonadotropins
-Females cyclic release
-Males noncyclic
What GENE is essential for male development to occur?
SRY - on the Y chromosome.
When is testosterone first produced in the male? Where?
Week 8 - in the developing testis.
When and Where do PGCs first appear in the Embryo?
-Fourth Week of Devo
-Wall of Yolk Sac
How do PGCs get to the developing Gonad?
By migrating from the yolk sac to the gonad via the Dorsal Mesentery of the intestine.
What are the attachments of the primitive gonad?
-Cranially
-Caudally
-Dorsally
Cranial: Suspensory ligament
Caudal: Gubernaculum
Dorsal: UG Ridge attachment
What does the Suspensory ligament become in males/females?
Males: Spermatic cord
Females: Suspensory ligament of the ovary
What does the Gubernaculum become in Males/Females?
Males: anchors testis to floor of scrotum
Females: Proper ligament of ovary and round ligament of uterus
What happens to the dorsal attachment to the UG ridge in males?
It disappears as the testis descends into the scrotum.
What does the dorsal attachment to the UG ridge become in females?
Broad Ligament
Where are the gonads devloping?
Retroperitoneally
What are the 2 pairs of ducts that form in the Int Mesoderm?
-Mesonephric - Wolffian
-Paramesonephric - Mullerian
What gives the inductive signal for PMDS to form?
MDs
What makes the MD stay in the male and disappear in the female?
Testosterone
How do the PMDs to form?
Coelomic epithelium invaginates and covers the intermediate mesoderm LATERAL to the MD
How do the PMDs not stick around in males?
They are induced to ATROPHY by Mullerian Inhibitory Substance
Where is MIS from again?
Secreted by the testis.
How does the PMD connect to the outside?
It fuses with the Cloaca - as the lower 1/3 of each tube fuses together too.
What results from the PMD fusing to the cloaca backside?
A genital tubercle that will form the lower vagina.
3 Primordia of External Genitalia:
-Genital tubercle
-Urethral folds
-Labioscrotal swellings
What is the Genital Tubercle?
An elevation superior to the cloacal membrane; unpaired midline structure.
What is the adult deriv of the Genital Tubercle in
-Males
-Females
Males: Glans and Penis

Females: Clitoris
Why is the SRY gene ESSENTIAL for male differentiation?
Because it encodes a protein called TESTICULAR DETERMINING FACTOR that results in the testes forming.
What does TDF do and where is it expressed?
-Expressed in UG ridge cells
-Tells the indifferent gonad to become a testes by directing cell differentiation.
What do the 3 precursor cells in the indifferent gonad differentiate into in males?
PGC -> spermatogonia
Sertoli cells
Leydig cells
What is the role of Sertoli cells?
To associate with PGCs as they become spermatogonia and become SEMINIFEROUS CORDS.
What is the role of Leydig cells?
Secrete testosterone
What cells give rise to the Sertoli and Leydig cells?
Coelomic epithelial cells
So the 2 main secretions of the Male Testes are:
-Testosterone
-Mullerian inhibiting factor
What is the active form of Testosterone?
Dihydrotestosterone
What happens when the SRY gene is not present?
Ovarian development occurs by default.
What causes the SRY gene to not be present?
No Y chromosome
What do the PGCs become in females?
Oocytes
How does PGC maturation differ between males and females?
-Females oocytes progress to Meiosis Prophase 1 then arrest.
-Males spermatogonia DON'T.
What is the role of Follicle cells in the developing ovary?
Associate with oocytes to form primordial follicles.
What happens to the Genital Tubercle that makes it become a penis?
It elongates into a Primordial Phallus
What influences the indifferent Primordial phallus to become male?
Dihydrotestosterone
What is on the Ventral side of this Phallus?
Urethral folds - they become fused overtop the Urethral groove
What type of tissue is the urethral groove?
Endoderm - it becomes the lining of the penile urethra.
What type of tissue is the distal penis? How does it form?
ECTODERM - ingrowth forms GLANS.
How does the Scrotum form?
The labial scrotal swellings approach each other and fuse.
What happens to the female primordial phallus if no androgen is around?
It doesn't enlarge/elongate.
What does the primordial phallus become in the female?
Clitoris
How does the development of urethral folds differ in females compared to males?
They DON'T fuse - instead become labia minora.
What happens to the labioscrotal swellings in the female?
They also don't fuse, becoming labia majora. UNZIPPED
What is EPISPADIUS?
Condition where penile urethra is open dorsally
What is epispadius commonly associated with?
Exstrophy of the bladder.
What is hypospadius?
Opening of the penile urethra on the VENTRAL side PROXIMAL TO THE GLANS TIP.
What causes hypospadius?
Incompete fusion of the urethral folds.
What usually causes abnormal development of the uterus?
Failure of the lower 1/3 of the PMDs to fuse together and with the uterus.
What happens when the lower 1/3 of the PMDS fail to fuse?
Duplex uterus
What happens if there is PARTIAL fusion of the distal 1/3 of the PMDs?
Bicornuate uterus - only the superior part of the uterus is unfused.
What would result if the wall between 2 successfuly fused PMDs failed to atrophy?
A midline septum would be present in the uterus.
What is the most common cause of ambiguous genitalia?
Abnormal testosterone representation in utero.
What is the definition of a true hermaphrodite?
-Gonadal tissue from each sex
-Either separate ovaries/testes
-Or a combined ovitestis
What is a Pseudohermaphrodite?
A person with the genotype of one sex, and variable expressions of the phenotype of the other sex.
What are the features of a male pseudohermaphrodite?
-XY chromosome
-Testes, no uterus
-variable feminine features
What is usually the cause of Male pseudohermaphroditism?
Testicular feminization - insensitivity to testosterone
What do individuals with complete androgen insensitivity develop?
Breasts and female external genitalia - but they don't have a uterus and do have testes.
What is the cause of testicular feminization?
A defect in the androgen receptor mechanism
Features of a female pseudohermaphrodite:
-XX chromosome
-No testes
-Uterus
-MAsculine phenotype
What is a common cause of Female pseudohermaphroditism?
Congenital adrenal hyperplasia
What is Turner Syndrome?
Monosomy X
What is the Phenotype of Turner Sydnrome individuals?
Female
Where do the testes end up in the end, and how do they get there?
Retroperitoneal, in the deep inguinal rings; during week 26, pass through the inguinal ring to enter scrotum.
Where do the ovaries end up in the end, and how do they get there?
End in Pelvis, inferior to pelvic brim; attached to Gubernaculum -> round ligament of the uterus/ovarian ligament.
What is from the Gubernaculum
-Cranial part
-Caudal part
Cranial = ovarian ligament
Caudal = round ligament of ovary
Where on the uterus is the gubernaculum attached?
Near the uterine tube.
Where is the termination of the Round ligament of the uterus?
Passes through the Inguinal canal and terminates in Labia Majora