Male Reproduction Flashcards
What do the testes (male gonads) do?
produce sperm (by spermatogenesis) and sex steroid hormone testosterone
What is the reproductive tract?
system of ducts specialized to store and/or transport sperm
What are the 3 parts of the reproductive tract?
- epididymis
- vas deferens
- urethra
What does the vas deferens do?
connects testes with structures within pelvic cavity – travels along urinary bladder to the back
What do accessory sex glands do?
produce supportive secretions
What are the 3 accessory sex glands?
seminal vesicles
prostate
bulbourethral (Cowper’s) glands
What is the penis?
copulatory organ
What does the penis contain?
- spongy (penile) urethra
- erectile tissues – one corpus spongiosum, two corpora cavernosa
What is the spongy (penile) urethra?
part of urethra within penis
What does the corpora cavernosa contain?
blood vessels (erection)
Spermatogenesis
What does spermatogenesis require?
relatively low temperature
optimal temperature for sperm production is 34-36 ºC
Spermatogenesis
What are the specific adaptations that result in lowering temperature of testes? (4)
- superficial location of testes in scrotum
- dartos muscle
- cremaster muscle
- pampiniform plexus
What is the dartos muscle?
smooth muscle found just directly under skin that forms small wrinkles that can cause surface area to change slightly
What is the cremaster muscle?
skeletal muscle that contracts to bring testes closer to body cavity (occurs when temperature of external environment is low)
What is the pampiniform plexus?
network of veins and single artery
Spermatogenesis
Where do testes go during fetal development?
descend from inside body cavity adjacent to kidneys to scrotum
Spermatogenesis
During embryonic life, what develops high on the posterior abdominal wall?
testes, their ducts (epididymis and vas deferens), blood vessels, and nerves
What does retroperitoneal mean?
area outside or behind the peritoneum (the tissue that lines the abdominal wall and covers most of the organs in the abdomen)
What does intraperitoneal mean?
within or administered through the peritoneum
Spermatogenesis
By the 3rd month, where are testes?
descend to pelvis
Spermatogenesis
By time of birth, where are testes?
enter scrotum
Spermatogenesis
What happens if testes stayed in body cavity?
spermatogenesis cannot occur (too warm)
Spermatogenesis
What does each testis consist of?
series of ducts including about 800 sperm-producing seminiferous tubules
Spermatogenesis
What are Sertoli cells?
cells that line walls of seminiferous tubules – essential for proper sperm development
Spermatogenesis
What are Leydig cells? What do they do?
cells located between seminiferous tubules that secrete sex steroid hormone testosterone
Spermatogenesis
What do seminiferous tubules eventually combine to form?
epididymis, which then forms vas deferens
Where does spermatogenesis take place?
within seminiferous tubules
Spermatogenesis
How do germ cells develop?
in close relationships to sertoli cells
Spermatogenesis
How long do men produce sperm?
throughout their adult lives (from puberty until death)
Spermatogenesis
What is mitosis?
biological process that allows spermatogenesis to continue uninterrupted for decades
Spermatogenesis Stages
- spermatogonium (23 chromosomes)
- primary spermatocyte (23 chromosomes)
- secondary spermatocyte (23 chromosomes)
- spermatids (46 chromosomes)
- spermatozoon (46 chromosomes)
Spermatogenesis Process
- spermatogonium undergoes mitotic proliferation into primary spermatocyte – one daughter cells enters spermatogenesis, and one daughter cells becomes next generation
- primary spermatocyte undergoes meiosis I → becomes secondary spermatocyte
- secondary spermatocyte undergoes meiosis II → becomes spermatids
- spermatids undergo spermatogenesis (maturation of sperm) → becomes spermatozoon
Where do sperm go following spermatogenesis?
enter epididymis and vas deferens where they undergo maturation and storage, respectively
Spermatogenesis
What is endocrine activity of testis regulated by?
hypothalamic-pituitary-testis axis
Endocrine Activity of Testis is Regulated by Hypothalamic-pituitary-testis Axis
Steps
- hypothalamic GnRH induces LH and FSH release from anterior pituitary
- LH controls testosterone production (binds to Leydig cells), and FSH controls spermatogenesis (binds to Sertoli cells)
- testosterone provides negative feedback effect on production of GnRH, LH, and FSH
- testosterone has negative feedback on hypothalamus and anterior pituitary
- release of hormones is always controlled by negative feedback - inhibin produced by Sertoli cells provides negative feedback effect on production of FSH only (inhibits release of FSH)
