Male Repro Physio Flashcards
What gene on the Y chromosome is crucial for male development? What protein does this gene code for? Name 3 other genes/proteins that are important for male development.
SRY gene is found on the Y chromosome. It codes for testis-determining factor (TDF). SOX-9, SF-1 and Androgen Receptor are also crucial for male development.
For the development of male gonads, what is the function of testosterone? What of Anti-Mullerian Hormone (AMH)?
Testosterone has a local effect of stimulating the development of the Wolffian Duct into the male internal genital tract. AMH regresses the Mullerian Duct, that would have become the default female internal genitalia.
What 3 structures does the Wolffian duct develop into? What of the Mullerian Duct?
Wolffian duct develops into the Seminal vesicles, Vas deferens and Epididymis. The Mullerian Duct forms the Fallopian tubes, Uterus and Upper Vagina (in absence of AMH and testosterone)
In the absence of __________ the genital tubercle, urogenital sinus and urethral folds develop into female external genitalia (clitoris, labia minora/majora and lower vagina).
Absence of dihydrotestosterone (DHT) results in female external genitalia.
For males, the timed production of _______, ______ and ______ is critical for normal development of the male internal genital tract and external genitalia.
Testosterone, AMH and DHT
What are the 3 accessory glands of the male reproductive system and their functions?
Seminal vesicle - secrete fluid rich in fructose that is a nutrient for sperm.
Prostate gland - secretes alkaline fluid to neutralize acidic environment of vagina.
Cowper’s glands - produce viscous secretion that neutralizes acid and lubricates urethra for sperm passage
Name the 2 functions of the testis. What are the 4 stages of spermatogenesis from basolateral side to the lumen of the seminiferous tubules?
Testis are the site of sperm and androgen production. From BM to lumen, maturation goes from Spermatogonium > Spermatocyte > Spermatid > Spermatozoon
“GCTZ = Gonium, cyte, tid, zoon “
Describe the significance of tight junctions in the Blood testis barrier. (Provide 2 reasons for their importance).
Tight junctions of BTB prevent harmful substances from entering the adlumenal region and prevent flagellated sperm from entering circulation, which could trigger an immune response.
The function of _______ cells is to nourish developing sperm and create the blood-testis barrier. ______ cells secrete androgens and ________ are at Prophase I.
Sertoli cells;
Leydig cells of the interstitium;
Spermatogonia
What 3 enzymes do the adrenal cortex and Leydig cells of the testis have in common? What new enzyme is expressed in Leydig cells but not in the adrenal gland?
CYP11A, 3-Beta-HSD, and CYP17 are 3 enzymes found in both tissues. 17-Beta-HSD is found exclusively in Leydig.
Testosterone can be converted into the more potent DHT via the _________ enzyme. More than 95% of total testosterone/DHT in adult males can be found in ______.
5-alpha-reductase enzyme found in androgen-responsive target tissues. T/DHT found in the testes, a minority comes from the adrenal gland.
Where does most DHT production occur? Provide an example.
DHT is predominantly produced outside the testes in androgen-responsive target tissues such as the prostate.
For both males and females ________ is an obligate precursor to estradiol; meanwhile, _____ is the same for estrone. The enzyme responsible for converting both of these reactions is __________
Testosterone = E2 precursor; Androstenedione = Estrone precursor;
Aromatase (CYP19)
The body cannot synthesize androgens without what key cholesterol derivative?
Estrogen (E2)
LH stimulates _____ cells which secretes _______ that negatively feedbacks ________ production of the hypothalamus and ______ secretion from the pituitary gland.
Leydig cells secrete testosterone which negatively feedbacks GnRH and LH secretions
FSH gonadotropin stimulates _______ cells which secretes _______ that negatively feedbacks _______ and ______ on HPA.
Sertoli cells secrete inhibin which suppresses FSH (from pituitary gland) and GnRH from hypothalamus.
_________ is secreted from multiple tissues (including the pituitary gland) to act in a _______ manner in gonadotropes.
Activin acts in a paracrine manner to stimulate FSH and maybe GnRH secretions. This is the opposite function to that of inhibin.
GnRH is secreted into the pituitary gland in a ________ manner, with one event every _____ hours in the post-pubertal male.
PULSATILE manner;
1 pulse per 3 hours
Why is there an increase in gonadotropin secretion rate in both males and females during senescence? Which gonadotropin is in greater quantity?
Due to the lower levels of androgens (estradiol and testosterone) than in adulthood, there is less negative feedback at the HPA which explains why gonadotropins FSH and LH rise. FSH is in greater quantity than LH.
In the adult reproductive period what gonadotropin hormone is in greater quantity? Describe one difference in secretion between males and females at this stage of life.
LH > FSH in both males and females. Menstrual cycles explain the fluctuating secretions of gonadotropins every 28 days; whereas males are elevated but plateaued.
In males, plasma testosterone is _____ in adulthood but _________ during senescence. How does the latter stage relate to gonadotropin levels?
Testosterone is high in male adults, but decreases during senescence. Gonadotropin levels rise as testosterone tapers off.
What is Testosterone’s effect on Sertoli cells?
Testosterone stimulates Sertoli cells to make more androgen binding protein and TGF’s to help speed the process of spermatogenesis.
Describe 2 androgen signaling pathways that circulating testosterone can take once it enters the cell of an effector tissue.
- Testosterone (T) can be converted to Estradiol (E2) and bind to estrogen receptor.
- T can be converted to DHT via 5-alpha-reductive which binds to androgen receptor to homodimerize and elicit secondary male development characteristics.
The prostate gland is entirely dependent on what androgen for growth?
DHT
