Key Terms
Gamete
Haploid reproductive cell (23 chromosomes); combines with another gamete at fertilization to restore 46. Gonad: organ th
Sperm
Male gamete. Smaller of the two.
Scrotum
Muscular sac that houses the testes outside the body cavity.
Optimal temperature for spermatogenesis
2 to 4 degrees C BELOW core body temperature.
Dartos muscle
Subcutaneous layer of scrotum; forms the scrotal septum dividing it into two compartments. Cremaster muscle: descends fr
Cryptorchidism
Testes normally descend through the inguinal canal into the scrotum during the seventh month of fetal development.
Tunica vaginalis
Outer serous membrane (parietal and visceral layers).
Tunica albuginea
Tough white connective tissue directly over the testis; invaginates to form septa that divide the testis into 300 to 400
Sperm path inside the testis
Seminiferous tubule lumen -> straight tubules (tubuli recti) -> rete testis -> 15 to 20 efferent ductules -> exits testi
Function
Surround and support all stages of developing sperm; secrete signaling molecules that promote sperm production; control
Location
Seminiferous tubules. Onset: puberty.
Testicular testosterone concentration
100 times higher inside testes than in systemic circulation — required to maintain spermatogenesis.
Step-by-step
1. Spermatogonium (diploid stem cell, basement membrane) undergoes MITOSIS.
Result
One functional ovum per cycle. Up to three polar bodies form; all degrade.
Head
Compact haploid nucleus. Very little cytoplasm.