1
Q
Formation of the testes after conception?
A
- first 40 days gonads of males and females are similar
- cells that give rise to spermatogonia and oogonia migrate from yolk sac to developing embyryonic gonads
- Testis-determining factor (TDF) promotes the conversion to the testes - seminiferous tubules appear w/in 43-50 days following conception - produce:
germinal cells - sperm
nongerminal cells - sertoli cells
leydig cells: appear about day 65 - these secrete testosterone - beings at 8th wk and peaks at 12-14th wk - this masculinizes embryonic structures - testosterone then declines to very low levels until puberty - testes descend into scrotum shortly b/f birth
2
Q
structure, formation of testes?
A
- testes (male gonads): 2 egg shaped structures outside abdominal cavity in the scrotum
- testes develop in abdominal cavity and then descend through the inguinal canal into pouch of peritoneum (tunica vaginalis)
- 80% spermatogenesis and 20% testosterone production
- arteries, veins and nerves
3
Q
Testicular descent?
A
- 2 stages:
7-12 wks fetal life (AMH)
7-9 months fetal life (testosterone) - undescended testicle - higher risk for testicuar cancer
4
Q
Scrotum fxn, components?-
A
- temp control and protection
- houses testes
- dartos muscle (wrinkles em): smooth muscle - change in temp - can modify surface area, also sep. testes
- cremaster muscle: (elevates em) - skeletal muscle
5
Q
Components of testes? Passage of sperm?
A
- composed of several hundred lobules
- each contains one or more colied seminiferous tubules - site of sperm production
- tubules lead into efferent ducts and become the rete testis
- 10,000-20,000 efferent ducts emerge to join the epididymis (further maturation occurs)- sperm still can’t swim, so they rely on peristaltic movements of ductal walls of epididymis
- spermatozoa continue migration through vas deferens - the ampulla serves as storage reservoir for sperm - until ejaculation
6
Q
How long can sperm live in ampulla of vas deferenes after vasectomy?
A
- 42 days
7
Q
accessory organs - fxn?
A
- seminal vesicles: secrete fluid high in fructose and prostaglandins (increase peristaltic contractions, he;ps sperm get through cervical mucus)
- prostate gland: add alkaline fluid during ejaculation - easer fertilization (urine and vagina acidic)
- bulbourethral glands (cowper glands): on either side of membranous urethra - secrete alkaline fluid
8
Q
Components of penis?
A
- shaft that ends in tip - glans
- loose skin of penis shaft folds to cover the glans (foreskin)
- corpora cavernosa - 2 lateral compartments
- corpus spongiosum - ventral compartment
9
Q
Negative feedback of hypothalamus and pituitary? When does testosterone gradually decline?
A
- will inhibit GnRH from hypothalamus and inhibits ant. pituitary response to GnRH - inhibin secretion inhibits ant. pituitary release of FSH
- male - testosterone - leads to negative feeback of LH and and GnRH prod. - maintain a relatively constant secretion of LH and FSH
- declines gradually in men over than 50, inhibin inhibits FSH secretion
- aromatization rxn producing estradiol in brain is reqd for negative feedback effects
10
Q
What is responsible for initiation and maintenance of body changes in puberty? What are other fxns of this hormone?
A
- testosterone and derivatives are responsible for initiation and maintenance of puberty
- stimulate growth of muscles, larynx, bone growth until sealing of epiphyseal discs
- promotes hemoglobin synthesis
- act in paracrine fashion, responsible for spermatogenesis
11
Q
Testes and relationship w/ hormones?
A
- seminiferous tubules: contain receptor proteins for FSH in sertoli cells, FSH stimulates spermatogenesis to occur
- Leydig cells: LH stimulates secretion of testosterone. Contain receptor proteins for LH
- androgens secreted by interstitial cells of leydig (20% of mass of testes) under influence of LH from ant. pituitary
- leydig cells not fully mature until about 10yo
- testosterone is sig. hormone responsible for male hormonal effects
12
Q
How does testosterone determine the development of sex organs? What stim. the testosterone secretion?
A
- embryonically testosterone is THE determining factor in development of male or female genital organs and characteristics
- hCG - which is produced by placenta stim. testosterone secretion in the fetal testes
13
Q
Testosterone and testes descent?
A
- stim. for descent of testes during last 2-3 months of preg.
- if male child is born with undescended testicles - admin of testosterone or LH, can cause testes to descend in usual maner if inguinal canals large enough (not usually done, 80-90% of undescended testes will descend by 1yo)
14
Q
Testosterone’s role in primary and secondary sexual characteristics?
A
- primary: causes penis, scrotum, and testes to all enlarge during puberty
- secondary:
molecularly almost all of these effects occur b/c of increased rate of protein formation -
distribution of body hair
baldness
deepened voice
skin: increases thickness, more prone to acne
muscular development
bone growth, bone density, Ca retention
15
Q
Disorders of embryonic sexual development?
A
intersex
- both ovarian and testicular tissue is present in body
- individual with either testes or ovaries but not both:
have accessory sex organs and external genitalia that are incompletely developed or inappropriate,
MC cause of female pseudohemaphroditism is congenital adrenal hyperplasia.
In the male, one cause is testicular feminizing syndrome: normal fxning tests, but lack receptors for testosterone
16
Q
Causes of low testosterone?
A
- hypogonadism (testosterone less than 300)
- trauma to Leydig cells
- mumps
- Rx/chemo
- testicular tumors
- HIV/AIDS
- ETOH
17
Q
Male reproductive fxns?
A
- spermatogenesis
- male sexual act
18
Q
Process of spermatogenesis? Sertoli cells contribution?
A
- spermatocytes divide into 2 stages, one of which is by process of meiosis to form 4 spermatids, each containing 23 unpaired x’somes
- spermatids mature for 2 months until they become spermatozoa
- fxn of sertoli cells: actually envelope spermatids for processing b/f release into lumen (protect and nurse sperm)
19
Q
Fxn of sertoli cells?
A
- form blood-testes barrier:
prevents autoimmune destruction of sperm, produce FAS ligand which binds to FAS receptor on surface to T lymphocytes, triggering apoptosis of T lymphocytes - prevents immune attack - secretes inhibin, FSH
- phagocytize residual bodies: may transmit information molecules from germ cells to sertoli cells
- secrete ABP - binds to testosterone and concentrates in the tubules
20
Q
Hormonal control of spermatogenesis?
A
- formation of primary spermatocytes and entry into early prophase I, begin during embryonic development - spermatogenesis arrested until puberty
- testosterone reqd for completion of meiosis and spermatid maturation
- secrete paracrine regulators: IGF-1, inhibin, transforming growth factor
- FSH necessary in later stages of spermatid maturation
21
Q
Pathway of sperm?
A
- sperm formed in seminiferous tubules (900 seminiferous tubules make up the testes)
- sperm emptied into epididymis (maturation) - sperm becomes fully motile (inhibitory proteins in epididymal fluid prevent motility until after ejaculation), and go through final maturation (becoming capable of fertilizing ovum)
- vas deferens - most of mature sperm is stored in Vas deferens (can maintain fertility for at least a month)
- prostate gland (seminal vesicle empties at this pt)
- onto urethra where it exits through the meatus
22
Q
Process of spermatogenesis, where does this start?
A
spermatogenia to primary spermatocyte to secondary spermatocyte to spermatid to spermatozoa (sperm cell) - these are in seminiferous tubules along with sertoli cells
- starts at pituitary gland - FSH regulates conversion of spermatogonia into spermatocytes
testosterone is necessary for final maturation of sperm cells and this is stim. by LH, both LH and FSH from pituitary, begins at 14 and continues throughout life
23
Q
Fxn of seminal vesicle?
A
- secrete mucoid material containing fructose, citric acid, prostaglandins, and fibrinogen: provides nutrients to sperm, prostaglandins thought to work on cervical mucus making it more receptive to sperm movement
24
Q
What is semen? Max life span of sperm once ejaculated?
A
- semen: fluid from vas deferent, seminal vesicles, prostate gladns, as well as bulbourethral glands and glands of urethra
- once ejaculation has occurred, max life span of a sperm is only 24-48 hrs at body temp, may be stored for several wks at lower temp and preserved for yrs if frozen
- avg sperm count per ejaculate is about 400 mill, if this falls below 70 mill/3.5 ml person is likely to be infertile
25
What is oligospermia? Causes?
- sperm count of less than 20 mill/ml ejaculate
| - decreased fertility caused by heat, pharmaceuticals, and ilicit drugs
26
Male contraception? Vasectomy?
- contraception: compounds that suppress gonadotropin secretion - testosterone and progesterone and GnRH antagonist (in the works)
- vasectomy: each ductus deferens is cut and ties, interferes with sperm transport, may develop anti-sperm abs - find diff route
27
Fxn of epididymis? Ductus deferens?
- maturational changes
- resistance to pH changes and temp
- storage of sperm b/t ejaculations
- ductus deferens:
carries sperm from epididymis into pelvic cavity
28
Secretion of seminal vesicles and prostate?
- seminal vesicles:
fructose
- prostate:
alkaline fluid, citric acid, Ca2+ , coag. proteins
29
Onset of puberty?
- 1st 10 yrs of life pituitary secretes almost no gonadotropins and consequently the testes secrete no testosterone
- following this, progressively increasing amts of gonadotropins released
- usually by 13 - male reaches adult sexual capability
30
Nerves involved in male sexual act?
- most impt sensory nerve signals are located in glans penis
- impulse is via pudenal nerve - sacral plexus - sacral portion of spinal cord, finally up cord to undefined areas of brain
- psychic stimuli alone can cause the male sexual act to occur and culminate in ejaculation
- direct stim. can also cause ejaculation independent of brain
- in general combo of both is what allows sexual act to occur
31
Stages of male sexual act: erection?
- caused by parasympathetic impulses from sacral portion of spinal cord to penis, parasympathetic signals lead to dilation of arteries in penis and high pressure flow into erectile tissue
32
Stages of male sexual act: lubrication?
- parasympathetic impulses also stimulate mucous glands along urethra and bulbourethral glands to secrete mucus through urethra during intercourse to aid in lubrication, most of lubrication is provided by female sexual organs
33
Stages of male sexual act: emission and ejaculation?
| Resolution?
- sympathetic nervous fxn:
emission - when stimulus intense enough - contraction of vas deferens and ampulla to cause expulsion of sperm into internal urethra, then seminal vesicles and prostate gland follow forcing sperm forward followed by:
ejaculation - rhythmic release of ejaculate
- resolution: w/in 1-2 min, excitement disappears and erection ceases
34
Prostate gland fxn? How does structure change, influenced by?
- protector, tubuloalveolar exocrine gland
- remains relatively small throughout childhood but begins to grow at puberty under influence of testosterone
- store and secrete 25% of semen - milky fluid containing citrate, Ca2+, among other items with pH of (6.5-7.5)
- stationary size from 20-50yo
- size of prostate influenced by testosterone
- needs androgens
- zones and lobes
- secretes fluid that nourishes and protects sperm, during ejaculation, prostate squeezes fluid into urethra, and expelled with sperm as semen
35
Meds used in BPH?
- alpha blockers: relax muscles around urethra in men w/ sxs from enlarged prostate, urine then flows more freely (SE: orthostatic hypotension - vasodilation everywhere)
- 5-alpha-reductase inhibitors: reduce level of certain form of testosterone (DHT), prostate shrinks when less DHT is present, improving urine flow
36
Location, layers of bladder?
- b/t pubic symphysis and rectum
- holds 300-350 ml of urine
- transitional epithelium (doesn't produce mucus)
- smooth muscle chamber
- smooth muscle called detrusor muscle and is innervated by parasympathetic fibers:
fibers extend in all directions, contraction (reflex, not voluntary) - increases pressure and bladder expels urine
37
Sphincters of bladder?
- external sphincter: skeletal muscle which is under voluntary control this can be used to consciously prevent urination even when involuntary controls are attempting to empty bladder
- internal sphincter: smooth muscle involuntarily controlled w/ natural tone, and therefore prevents emptying of bladder until pressure in main part of bladder rises above critical threshold
-
38
Bladder emptying contolled - sensory fibers, ureter placement?
- sensory fibers: detect degree of stretch in bladder wall which triggers reflexes responsible that causes bladder emptying
- ureters: course obliquely for several cms through bladder wall - so normal tone of bladder prevents reflux. peristaltic contractions of ureter is what allows urine to deposit into bladder
39
What can cause urinary obstruction and stasis?
- congenital narrowing of external meatus
- sacral nerves damage
- compression of urethra (enlarged prostate gland)
- urethral strictures (often from STDs)
- compression of bladder neck or urethra from bladder tumors
- constipation and fecal impaction can compress the urethra
40
Where is most mature sperm stored? Where does spermatogenesis begin?
- stored in ampulla of vas deferens
| - begins at pituitary and hypothalamus
41
17yo boy presents to clinic w/ complaint of acne (plays football and under a lot of pressure from dad) - on PE - well nourished except grade II-III acne and bilateral borderline shrunken testes (just over 3 cm in length, normal - 3.5-5.5 cm) - most likely dx? other signs and sxs?
- use of exogenous anabolic steroids (neg feedback on pituitary - decrease stim of LH and decreased prod. of testosterone)
- low sperm count
- decreased libido
- gynecomastia
- increased aggression
42
Max life span of sperm at room temp?
- 24-48 hrs
43
parasympathetic signals cause? sympathetic?
- parasympathetic: erection and lubrication
| - sympathetic: emission and ejaculation
44
FSH and LH fxn?
FSH - facilitation of spermatogenesis
LH - testosterone (leydig cells)
- both needed to produce mature sperm
45
Do men have hCG?
- no, if they do - somethings up - may be testicular CA
