Reproductive Endo in Males Flashcards
Absence of Testosterone –>
Absence of AMH –>
Absence of Testosterone –>
Wolffian ducts involute
Absence of AMH –>
mullerian ducts spontaneously differentiates
Development of female ducts and external genitalia is independent of _____
gonadal hormones
*if no gonads, female formation results
Sertoli cells
- Testis formation
- Nurture sperm
- germ cells –> spermatogonia (consumes cytoplasm of germ cells) - Forms tight junctions - blood testis barrier
- or else autoimmune response to sperm - Convert androgens to estrogens (via aromatase)
- Secrete inhibin, GF, aromatase, Androgen binding protein
*Respond to FSH thru GPCR (not LH like leydig)
Leydig cells
- required for spermatogenesis
- Synthesis of testosterone (95%)
- Synthesis of Steroidogenic acute regulatory protein (StAR) and sterol carrier protein (SCP)
- Respond to LH through a GPCR
Are Leydig or sertoli cells necessary for testicular fxn?
both
Inhibins released from sertoli cells in response to FSH cells act locally as growth factors for Leydig cells
FSH (acting on sertoli cells) regulates proliferation and devel of leydig cells to provide adequate T for spermatogenesis
T from leydig cells synergizes with FSH to increase Androgen binding protein (ABP) production in sertoli cells to maintain high local T [ ]
HPT Axis:
GnRH stimulates production of ___ + __ from pituitary. What do they act on?
LH –> acts on Leydig cells
FSH –> acts on Sertoli cells
HCG in athletes
Looks like LH (stim fetal tetes to make T)
If they abuse T, then stop taking them, their T lvls would drop.
Stop Taking HCG:
Turns back on normal endogenous production.
- Restore physiologic Testosterone levels
Inhibin
suppresses FSH production from pituitary gonadotrophs
Testosterone inhibits release of ____ from ____.
Estrogen inhibits ____ from ____.
T: inhib GnRH from hypothal
E: inhibit LH + FSH from pituitary
Sertoli cell only syndrome
all levels are normal, but you have no gametes
may have patches of gametes
What would sperm count look like in indiv who abuse T?
Exogenous T would shut down fxn of testis and not make any sperm
- also see shrinkage
Male pubertal growth is due to?
- Increased GH
- Increased T
Pubertal growth spurt
Pre-pubertal males equal. . .
body mass,
skeletal mass
body fat
(then after: everything increases except for fat, males have 50% of female body fat)
Androgenic effects
- GRowth and devel of male repro tract
- 2ndary sexual characteristics
- Behavioral responses
Anabolic effects in puberty
- Growth of somatic tissue
- linear body growth (long bones)
- Nitrogen retention, protein synthesis
- Muscle development
GH/IGF-1 stimulates
- gonadal function +
- body growth
(IGF-1 stimulates GnRH secretion)
*look at HPT axis
GH/IGF-1 and HPT axes
High GnRH --> Increase LH and FSH --> Increase gonadal fxn --> Increase T and E2 --> Increase body growth + GH
High GnRH –> Increase GH –>
Increase IGF-1 –>
Increase body growth
(chart in handout)
Prepuberty indiv abusing steroids
grows more rapidly but ends up as shorter statute
- promotes epiphyseal closure
- narrow growth window limiting long bone growth
Consequences of steroid abuse
lots
- infertility (decreased sperm prod)
- Gynecomastia
- Testicular atrophy
- baldness + excessive body hair
- Short stature
- Tendon rupture
- Increased LDL
Decreased HDL (atherosclerosis) - High BP
- Heart attack n stroke
10 Liver cancer - Severe acne
- kidney failure
- Psychiatric disturbances
