Sperms Flashcards
When does spermatogenesis begin?
Puberty w/ spermatogonia. 46 single chromosomes.
What does a primary spermatocyte contain?
Diploid - 46 sister chromatids. (sex chromosomes XX and YY)
What does a secondary spermatocyte contain?
haploid, 23 sister chromatids.
sex: XX or YY
What does a spermatid contain?
23 single chromosomes.
sex: X or Y.
What do spermatids undergo?
Spermiogenesis to become mature spermatozoon.
What changes occur in spermiogenesis?
Loss of cytoplasmic contents, gain of acrosomal cap, differentiation to head, nucleus, neck, middle piece, and tail.
What are the sources of androgens?
DHT and testosterone: testis
Androstenedione: ADrenal.
What are the roles of testosterone in development?
Differentation of mesonephric duct - internal genitalia except prostate
What are the roles of testosterone during male growth spurt?
growth of penis, seminal vesicles, sperm, muscle, RBCs.
Deepening of voice.
Closing of epiphyseal plates (bone)
Libido
How is testosterone converted to DHT?
5-alpha reductase
What inhibits 5-areductase?
Finasteride
What are the roles of DHT in development?
Differentiation of penis, scrotum, prostate
What are the roles of DHT later in life?
Prostate growth, balding, sebaceous gland activity.
How are androgens converted to estrogens in males?
cp450 aromatase primarily in adipose tissue and testis.
What is the effect of exogenous testosterone?
Inhibition of HP-gonad axis, decrease intratesticular testosterone, decrease testicular size –> azoospermia.
