Lecture 35: Male reproductive system part A

Question 1

what happens in spermatogenesis 1?

Answer 1

• spermatogonia divide by mitosis into 2 daughter cells (diploid - 46 chromosomes)
• one spermatogonium (type A) stays at the basement membrane of the seminiferous tubule

Question 2

what happens in spermatogenesis 2?

Answer 2

• the second spermatogonia (type B) differentiates into a primary spermatocyte (diploid) which undergoes meiosis 1
• it forms 2 secondary spermatocytes (haploid - 23 chromosomes)

Question 3

what happens in spermatogenesis 3?

Answer 3

• the 2 secondary spermatocytes undergo meiosis 2 to form spermatids (haploid)
• spermatids differentiate into spermatozoa with a head, body and tail via spermiogenesis
• spermatozoa are released into the lumen

Question 4

what is spermiogenesis and what key changes happen?

Answer 4

• spermiogenesis is when spermatid differentiates into spermatozoon (spermatozoa) and it takes approximately 24 days

key changes:
- formation of acrosomal enzymes which is important for fertilisation

• formation of flagella for forward motility
• mitochondria form around the midpiece for energy needed for motility
• gets rid of excess cytoplasm
• forms into head, midpiece and tail

Question 5

Question 6

explain the feedback loop of the hormones in males.

Answer 6

• GnRH from hypothalamus stimulates the anterior pituitary to release LH and FSH
• LH stimulates the production of testosterone from interstitial endocrine (leydig) cells
• FSH and testosterone control spermatogenesis
• FSH stimulates inhibit production from nurse (sertoli cells)
• inhibin suppresses FSH in negative feedback loop
• testosterone suppresses LH and GnRH

Question 7

Answer 7

Question 8

Answer 8

Question 9

Answer 9

Question 10

Answer 10