16 17 Male Reproductive Flashcards
What happens in the epididymis, ductus deferens, and urethra
system of ducts - Transport and stores sperm assists in their maturation, and conveys them to the exterior
What are examples of accessory sex glands
Seminal vesicles, prostate, and bulbourethral glands
What is the critical regulator of male reproductive function
androgens and other hormones
ALL functions & differentiation regulated by hormones
The first fetal repro structure is female, male, or both
Both
What does the Mullarian duct become? How is the process regulated?
Female repro organs - NOT under hormonal control
fallopian tube / oviduct
uterus
cranial 1/3 of vagina
What does the Wolfian duct become
Male repro organs - require MIS/AMH stimulation
epididymis
vas deferens
seminal vesicle
What do sertoli cells do to the male repro tract
secrete MIS/AMH to induce Mullerian duct regression
What do leydig cells do to the male repro tract
secrete testosterone to induce Wolffian duct development
What does MIS/AMH do?
Hormone produced by sertoli cells that causes Mullerian duct regression
What are the 3 phases of spermatogenesis
Proliferation
meiotic
differentiation
What drives spermatogenisis
Leydig cells and the androgens they produce
spermatogenesis is obligatory dependent on androgen
What are the two populations of Leydig cells
1) Fetal leydig cells
- differentiate prenatally
- produce androgens that induce normal development of male internal and external reproductive organs
2) Mature leydig
- develop at puberty
- drive spermatogenesis and other events
What do the testes do
produce androgen
produces sperm
What species have a prostate
present in all species
What species do not have seminal vesicles
absent in dogs and cats
What species do not have bulbourethal glands
bears, dogs, aquatic animals
What is the major producer of semen
seminal vesicles
What is cryptorchidism
Testicle doesn’t descend properly
0.8-15% of dogs
can be treated surgically & medically
if untreated more prone to tumors
What is Benign prostatic hyperplasia
begin NOT cancer
enlargement of the prostate gland
occurs only in dogs and humans
What causes BPH symptoms? Treatment?
age and time
clinical symptom in dogs: incontinence
Treatment: castration
gonads / testes
produces sperm
secretes hormones
What is the function of the male reproductive system
produces androgens & other hormones
produces male gametes
conveys the gametes from their site of production into the female reproductive tract
3 cells types in the testis that play critical roles in reproduction
germ cells - spermatogonia > spermatozoa sertoli cells - regulate germ cell development interstitial (leydig) cells - secrete testosterone, the major androgen
spermatogenesis
development of spermatids into sperm
65-75 days in humans - variable in species
sertoli cells important
What drives androgen production by Leydig cells?
hypothalamus releases GnRH into the blood stream →
GnRH triggers the release of pituitary LH and FSH → stimulate the testes to secrete testosterone and produce sperm
Hormonal control of the testes
a puberty > increased GnRH from hypothalamus > Anterior Pituitary increases secretion of LH and FSH
LH stimulates leydig cells to secrete testosterone
FSH acts indirectly on spermatogenesis
What does lutenizing hormone (LH) regulate in male reproduction
stimulates Leydig cells to secrete testosterone
- testosterone stimulates spermatogenesis
- synthesized from cholesterol in testes
- suppresses secretion of LH and GnRH via negative feedback
What does follicle stimulating hormone (FSH) regulate in male reproduction
acts on sertoli cells
- FSH & testosterone act on sertoli cells to promote spermatogenesis and stimulate secretion of androgen binding protein (APB)
- APB binds to testosterone keeping concentration high
- sertoli cells release inhibin which inhibits FSH
How does androgen act to support and promote spermatogenesis?
sertoli cells are the ONLY cells in the seminiferous tubules that express androgen receptor
androgens from the leydig cells act on sertoli cells to drive spermatogenesis
androgenic regulation of spermatogenesis is INDIRECT; germ cells do not have androgen receptor and are not responding directly to androgens
What are the functions of androgens produced in leydig cells?
- support spermatogenesis
- induce and maintain make accessory sex organs
- influence brain and sexual behavior
- promote protein anabolism, muscle mass, somatic and bone growth
- regulate secretion of gonadotropins
- induce secondary male sex characteristics (horns, mane, feathers, rooster comb, etc. )
What are some clinically important male repro diseases and problems in vet med
cryptorchidism
infertility
benign prostatic hyperplasia (BPH)
testicular tumors
testicular tumors
can occur in many diff cells in testes: - sertoli cell tumors - seminomas - interstitial cell tumors ALL can be malignant
