The Reproductive System Flashcards
What are the primary functions of the reproductive system?
- reproduction: to ensure the survival of the species of an animal
- rather than to maintain the homeostasis of the body, unlike all other systems
- not essential to the life of an animal
- completion of the full function requires a second opposite sex animal
What is included in the reproductive system?
gonads (testes and ovaries)
- produce gametes (spermatozoa and oocyte) and hormones
ducts: receive and transport the gametes
accessory glands: secrete fluids into the ducts
perineal structures: collectively known as external genetalia
What are the principal structures of the reproductive organs of a male?
- testes
- epididymis
- ductus deferens (vas deferens)
- ejaculatory duct
- urethra
What are the accessory glands of the reproductive organs of a male?
- seminal vesicles
- prostate glands
- bulbourethral glands
What are the external genitalia of the male reproductive organs?
- scrotum
- penis
What are the functions of the testes?
spermatogenesis: produce the male gametes (spermatozoa or sperm), half billion/day
male sex hormone production: androgen (principally testosterone)
- develop male secondary sex characteristics and male sex drive
- stimulate bone and muscle growth
What is the structures of the testes?
tunica vaginalis
- two layers of serous membrane: parietal (scrotal) and visceral (testicular)
septa subdivide testes into lobules
lobules contain about 800 slender and tightly-coiled seminiferous tubules
- 15-20 large efferent ductules connect the rete testis to the epididymis
What are the seminiferous tubules?
wall formed by specialized epithelium = sertoli cells (sustentacular cells)
cells at different stages of spermatogensis
leydig cells: outside of the wall
What are sertoli cells?
- support, nourish spermatogenesis
- move developing sperm cells to lumen of seminiferous tubules
- reduce motility of sperm cells to maintain viability
- mediate hormonal effects
- form blood-testis barrier
What is the relevance of sertoli cell tumor in intact male dogs?
- sertoli cell tumors can produce estrogen and a condition called hyperestrogenism
- hyperestrogenism can cause signs of feminization
- this includes enlarged mammary glands and nipples, a pendulous prepuce, hair loss, and hyperpigmentation (darkening) of the skin
What do interstitial cells (leydig cells) do?
produce androgens (testosterone)
What is spermatogenesis?
- is the process of sperm production
- begins at outermost cell layer in seminiferous tubules
- proceeds toward lumen
- meiosis produces gametes: that contain 1/2 of chromosomes in somatic cells
- for each cell entering meiosis: tests produce 4 spermatozoa (ovaries produce 1 ovum and 3 polar bodies)
What happens to the spermatozoa during sperm maturation?
detach from sustentacular cells (sertoli cells)
are free in lumen of seminiferous tubule
are functionally immature
are moved by cilia lining efferent ductules:
- into the epididymis
- facilitates functional maturation
Describe the regulation of testis functions by gonadotropin:
- FSH and testosterone, BOTH, are required for initiation of spermatogenesis during sexual maturation
- FSH and testosterone maintain the gametogenic function
- FSH - stimulates the proliferation and secretory activities of sertoli cells
- LH stimulates production of testosterone by Leydig cells
What are the functions of testosterone?
- higher libido
- increases muscle mass
- strengthens bone
- sperm production
- penis development
- development of phenotypic characterstics