Puberty

What is the major limiting factor to onset of puberty?

failure of hypothalamus to secrete sufficient quantities of GnRH

Hypothalamus is inherently _____________.

female

What does alpha-fetoprotein do?

prevents estradiol from crossing the blood-brain barrier in female

How is the surge center eliminated in the male?

testosterone crosses the blood-brain barrier and is androgenized to estradiol which causes defeminization.

What is a hormone that surges in the female?

LH (during ovulation)

Males do not have a _____________.

surge center

How often does GnRH pulse in the male?

every 2-6 hours

What is the best way to determine the onset of puberty in the female?

age at which she can support a fetus

What is the best way to determine the onset of puberty in the male?

age at which there is an adequate number of spermatozoa in the ejaculate

What are the 2 factors impacting hypothalamic GnRH neuron development in the female?

1. must reach threshold body size

2. exposure to certain environmental or social cues

What are the environmental factors affecting the onset of puberty in females?

season born, photoperiod, exposure to male, group size & density, breed

When do queens reach puberty?

January

What season do all lambs reach puberty?

fall

Fall-calved heifers tend to reach puberty ____________.

earlier

What species are affected by group dynamics?

cattle, swine

What type of switch is puberty compared to?

a dimmer switch