Male Puberty

Question 1

What could be observed to evaluate whether a male had gone through puberty

Answer 1

• hormones
• descended testicles
• antlers of a deer/main of a lion (sex characteristics)
• the presence of sperm in semen production
• if a male is interested in ejaculating

Question 2

What is puberty driven by overall? (think about hormones)

Answer 2

The HPG axis - hypothalamus, pituitary and the gonads

Question 3

Do males have a surge centre? What hormone is responsible for this?

Answer 3

• No they do not, oestrogen is responsible for the surge centre

Question 4

Explain why males do not have a surge centre?

Answer 4

• Fetal testis produces testosterone and enters the blood brain barrier as is not attached to a carrier
• it then gets converted into oestrogen in the hypothalamus, thus no surge centre is being developed
• oestrogen inhibits this from being produced

Question 5

Why do females have a surge centre?

Answer 5

• Fetal ovary produces oestrogen, but is unable to get across the blood brain barrier due to the carrier protein. Thus the surge centre develops due to lack of oestrogen

Question 6

Is GnRH low or high before puberty?

Answer 6

Low due to negative feedback

Question 7

is GnRH higher or lower during puberty? Why?

Answer 7

GnRH neuron sensitivities decrease during puberty thus higher GnRH secretion occurs -> thus allows other hormones to be secreted as well.

Question 8

What are the 3 time points in male development that increase HPG activity?

Answer 8

• gonad differentiation (pre natal)
• immediately post birth
  
  • during puberty

Question 9

What animal takes the longest to reach puberty?

Answer 9

• horses are about 14 years, and bulls are second at about 11 years

Question 10

What 4 intrinsic and extrinsic factors influence the onset of puberty (think food, Illness, intrinsic factors that would effect it)?

Answer 10

• Season of birth
• breed / genetics
• nutrition: higher nutrition = earlier puberty (problems with this?)
• chronic disease = delays puberty

Question 11

At what stage does meiosis begin in males

• fetal
• neonatal
• pubertal

Answer 11

• pubertal stage - meiosis begins = germ cell development

Question 12

What testicular changes occur during fetal stage?

1. gonocytes, immature sertoli cells and fetal leydig cells present
2. gonocytes differentiate to spermatogonia, mitosis resumes
3. meiosis begins = germ cell development, sertoli cells mature, adult leydig cells present

Answer 12

1. gonocytes, immature sertoli cells and fetal leydig cells present

Question 13

What does the size of the testes tell us about puberty?

Answer 13

• Tells us whether animal has reached puberty or not and also how much sperm the animal is producing/can produce

Question 14

What is the term for when a teste is retained retroperitoneal in a male?

Answer 14

cryptorchid

Question 15

What ligament does the testes attach to during foetal development when they are descending?

Answer 15

• the gubernaculum ligament
• growth of this ligament creates downward pull to move testes into inguinal canal, then into the scrotum