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22 Cards in this Set

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What three types of cells are in the epithelium lining the seminiferous tubules?
spermatogonia (stem cells), spermatocytes (in process of development), and Sertoli cells
What are the three main supportive functions of Sertoli cells?
1. provide nutrients
2. form tight jns to create blood-testes barrier
3. create aqueous fluid in lumen to help transport sperm to epididymis
During what life stages does spermatogenesis occur?
ENTIRE LIFE!
Spermatogonia -> ??????? -> Spermatozoon
spermatogonia -> mitosis -> generate primary spermatocytes -> meiosis I -> secondary spermatocytes -> meiosis II -> spermatid -> spermiogenesis -> spermatozoa
How long does one full cycle of spermatogenesis take?
64 days
How do prostaglandins secreted by the seminal vesicles aid in fertilization?
1. react w/cervical mucus to make it more penetrable
2. induce peristaltic contractions in female repro tract
How do prostate secretions aid in fertilization?
(rich in citrate, Ca, enzymes)
alkalinity increases sperm motility, neutralizes acidic vaginal secretions
How are sperm modified once they are in the female repro tract?
capacitation occurs: inhibitory factors washed free, surface proteins redistributed, surf cholesterol removed, Ca influx increases motility, acrosomal reaction
What is the acrosomal reation?
acrosomal membrane and sperm membrane fuse, releasing hydrolytic enzymes that can create a path for sperm to penetrate ovum's protective coverings
How does the testicular steroidogenic pathway differ from the adrenal steroidogenic pathway?
in testes:
1)no 21beta-hydroxylase or 11beta-hydroxylase = no glucocort/mineralocort
2)has 17beta-hydroxysteroid dehydrogenasae, which converts androstenedione to testost
What is the active form of testosterone in some tissues? How is this produced?
dihydrotestosterone (converted by 5alpha-reductase)
In what forms does testosterone circulate?
98% bound to sex steroid-binding globulin or albumin (acts as reservoir), 2% free (active)
What hormone stimulates the production of testosterone?
LH (stimulates cholesterol desmolase)
What type of inhibitor could be used to treat benign prostatic hypertrophy?
5alpha-reductase inhibitors (finasteride)
What type of cells does FSH stimulate?
Sertoli cells, to promote spermatogenesis
What type of cells does LH stimulate?
Leydig cells, to produce testosterone
What paracrine effect does testosterone have?
diffues to nearby Sertoli cells to reinforce spermatogenic action of FSH
What two substances exert negative feeback control over GnRH, LH, and FSH?
1. testosterone inhibits hypothal and s/c of LH from a/p
2. inhibin (produced by Sertoli cells) inhibits s/c of FSH from a/p
What are the prenatal actions of testosterone?
differentiation of internal genital tract (of wolffian ducts)
What are the prenatal actions of dihydrotestosterone?
differentiation of external male genitalia
What are the pubertal effects of testosterone?
increased muscle mass, growth spurt, closure of epiphyseal plates, growth of penis and seminal vesicles, deepening of voice, spermatogenesis, libido
What are the post-natal effects of dihydrotestosterone?
male hair pattern, pattern baldness, sebacious gland activity, growth of prostate