Chapter 19 - Reproductive System Flashcards
Gametogenesis
production of gametes
Oogenesis
gametogenesis in females; produces an ovum; takes 300 days to complete
spermatogenesis
gametogenesis in males; produces a spermatozoa; takes 74 days to complete
When does gametogenesis begin?
~5th week of embryonic development
Primordial Germ Cells (PGCs)
- migrate to genital ridges
- mitotically divide during migration and differentiate into appropriate gametogonia
Testis
- paired ovoid gonads that are housed in the pouch-like scrotum
- eachh testi is surrounded by the tunica vaginalis and tunica albuginea
tunica albuginea
projects internally to divide the testis into 200-300 distinct tubules, each containing 1-4 seminiferous tubules
seminiferous tubules are formed by:
interconnected sertoli cells
functions of seroli cells
- direct germ cell development
- scavenge cellular debris/damaged cells
- produce seminiferous fluid
- FSH-responsive
- produce inhibin
- produce androgen-binding protein (ABP)
Leydig cells
outside of seminiferous tubules; produce androgens
features of epididymis
- fluid and sperm cells travel through a series of tubules until converging into the epididyis
- lies againts the testis, coiled down to 1/2000th of its actual size
- divided into lobules; maintains tight junctions
- delivers sperm to ductus deferens, and promotes sperm fertilizing capacity
epididymis
long, thin, convoluted single duct
paired ejaculatory ducts
1-2 cm each; connect ductus deferens to urethra; mixes sperm cells with seminal plasma
Male urethra
divided into three layers:
1. prostatic urethra
2. membranous urethra
3. spongy urethra
What is the function of the male’s 3 urethra layers?
conduct semen out of the male reproductive tract during ejaculatioin
Features of the seminal vesicles
- excretory duct on each gland joins with ampulla of ductus deferens to firm ejaculatory duct
- Lumen consist of highly-convoluted irregular mucosa (increases surface area)
- surrounded by 2 layers of smooth muscle (squeezes products out during ejaculation)
Prostate gland features
- largest human accessory sex gland
- consists of many lobules that all open up into prostatic urethra
- produces ~30% of seminal plasma by volume
- secrets factors that promote sperm survival, activation and fertilization (citric acid, PSAP, zinc, prostate specific antigen, hCAP-18)
features of the bulbourethral gland
- 2 cm-long ducts join wiith spongy urethra
- secretions make up first fraction of ejaculate (5% of total)
- typically does not mix with sperm cells; sometimes called pre-ejaculate
- clear, alkaline fluid consists of lubricating prteins and neutralizing mucins
the penis
- elongated structure that grows in both girth and length during sexual arousal
3 parts of penis
- roots: attach penis to pelvic girdle
- body: contains penile urethra and corpora cavernosa
- glans: highly-sensitive bulbous structure at the end of penis
what is the primary function of the scrotum
maintains temperature of testes at 34ºC to promote spermatogenesis
Features of the scrotum
- suspended at base of pelvis; houses testes, epididymis and proximal portion of ductus deferens
- bisected at midline to create 2 compartments
- temperature monitored with thermoreceptors
- cremaster muscle