Puberty

Question 1

Describe puberty.

Answer 1

The PROCESS of a male or female to be able to complete reproduction successfully.

Question 2

What is required for pubertal onset in mammals?

Answer 2

Development of specific hypothalamic neurons to release GnRH at the correct frequencies.

Question 3

What can gonadotropins promote?

Answer 3

Gametgenisis, steriodogensis, and development of reproductive tissues

Question 4

What three things can puberty be influenced by?

Answer 4

Genetics, Reaching proper body size and exposure to certain stimuli

Question 5

List and describe the three puberty definitions in the female.

Answer 5

1) Age at first estrus-Usually not followed with ovulation.
2) Age at first ovulation- Determined by palpation, ultrasonography but must be frequently observed.
3) Age when a female can support pregnancy without deleterious effects

Question 6

List and describe the four puberty definitions in the male.

Answer 6

1) Age when behavioral traits are shown (mounting, erection)
2) Age at first ejaculation
3) Age when spermatozoa appear in the ejaculate
4) Age when the ejaculate has a threshold number of sperm.

Question 7

List the average ages for each species to reach puberty.

Answer 7

Cattle- 11 months
Sheep- 7 months
Pig- 7 (male) 6 (female)
Horse- 14 (male) 18 (female)

Question 8

Which species is most aware of the daylight when reaching puberty?

Answer 8

Sheep are very aware and the length of day will greatly affect their puberty time.

Question 9

What is the number one attribute contributing to puberty?

Answer 9

Both male and female must have hypothalamic GnRH neurons capable of releasing pulses of GnRH

Question 10

What are some metabolic signals that could affect the threshold body size for puberty?

Answer 10

• Leptin-produced from fat, keeps us from eating
• Insulin-store sugar
• NPY
• IGF-I

Question 11

List four external or social factors affecting puberty.

Answer 11

Season, Photoperiod, presence of the male, Rearing density

Question 12

Describe rearing density.

Answer 12

Giving pigs proper room. Not too crowded yet being around plenty of other pigs.

Question 13

What will the anterior pituitary produce before puberty when stimulated with GnRH

Answer 13

LH and FSH

Question 14

How will prepubertal animals respond to exogenous FSH and LH?

Answer 14

Produces follicules and estradiol

Question 15

When does development of the hypothalamus occur?

Answer 15

Gradually as the animal grows

Question 16

What causes the preovulatory LH surge at puberty?

Answer 16

Preovulatory GnRH surge

Question 17

Describe how frequency of GnRH is controlled

Answer 17

-Pulse Generator which reads internal signs (nutrients, serum E2)
and External Signals (day length and presence of opposite sex)

Question 18

Where is the pulse generator at?

Answer 18

Preoptic area and anterior hypothalamus

Question 19

What is the Gonadostat Theory of Puberty?

Answer 19

As puberty approaches there is a decrease in the sensitivity to the negative feedback efforts of E2.

Question 20

The hypothalams is inherently which gender?

Answer 20

female

Question 21

Which gender has a surge center?

Answer 21

Female because she doesn’t produce testosterone

Question 22

What must happen to testosterone to defeminize the hypothalamus.

Answer 22

It must be converted to E2

Question 23

Why is E2 prevented from crossing the blood brain barrier?

Answer 23

It is attached to alpha-fetoprtein that is too large to cross.

Question 24

What converts the testosterone to E2 after crossing the BBB?

Answer 24

aromatase enzyme

Question 25

What is the fundamental difference in endocrine profiles from a postpubertal male and female?

Answer 25

The LH does not surge in the male but surges for the female at estrus

Question 26

What are two important factors in regulating age of pubertal onset?

Answer 26

Age and amount of body fat

Question 27

How is environmental information received?

Answer 27

sensory neurons in the optic and olefactory systems, processed by the CNS and delivered as neural inputs to the GnRH neurons

Question 28

List three female species and their season of birth that will affect their age of puberty.

Answer 28

Sheep-Spring lambs reach puberty in half the time 5-6 months
Cows-Fall heifers will reach puberty sooner
Pigs-Fall born reach puberty faster