Spermatogenesis
& Semen
Animal Breeding
Pensacola Jr College
Puberty in Males
w LH pulses stimulate
maturation of Leydig cells
w Testosterone production
begins
w Sperm formed in seminiferous
tubules
w 2ndary sex
characteristics
Spermatogenesis
w Occurs constantly from
puberty on, groups of cells start 3 step cycle all the time (except seasonal
breeders)
w Cells in one region of
tubule start process at same time, creating spermatogenic wave
Steps of
Spermatogenesis
w Spermatocytogenesis =
formation of the spermatocytes
w Meiosis = formation of the
spermatids
w Spermiogenesis =
metamorphosis into sperm cell
1.
Spermatocytogenesis
w Begin with spermatogonia = round
stem cells on basement membrane of seminiferous tubules
w Undergo mitosis
w Each produces two diploid
primary spermatocytes
Spermatocytogenesis
2. Meiosis
Meiosis
3. Spermiogenesis
w Round spermatids attach to
sertoli cells and go through changes in form
w Nucleus moved to one end
w Mitochondria packed in one
area
w Cytoplasm lost
w Flagellum forms
Spermiogenesis
Spermiogenesis
Sperm Structure
w Head: has cell membrane,
acrosome (enzyme bag), nucleus
w Midpiece: has cytoplasmic
droplet, cell membrane, tightly packed mitochondria
w Tail: flagellum with
contractile fibers
Sperm (SEM)
Sperm Maturation
w In the epididymis:
• Gain motility
• Gain fertility
• Lose cytoplasmic droplet
w In female reproductive
tract:
• Final maturation process
Semen
w Fluids produced by male accessory
sex glands to maintain sperm cell homeostasis
w Ions (esp. Na and Cl)
w Buffers (esp. bicarbonate)
w Energy sources (esp.
fructose and sorbitol)
w Other unique compounds