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Livestock Reproduction 333 > Puberty > Flashcards

Flashcards in Puberty Deck (28)
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1
Q

Describe puberty.

A

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

2
Q

What is required for pubertal onset in mammals?

A

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

3
Q

What can gonadotropins promote?

A

Gametgenisis, steriodogensis, and development of reproductive tissues

4
Q

What three things can puberty be influenced by?

A

Genetics, Reaching proper body size and exposure to certain stimuli

5
Q

List and describe the three puberty definitions in the female.

A

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

6
Q

List and describe the four puberty definitions in the male.

A

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.

7
Q

List the average ages for each species to reach puberty.

A

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

8
Q

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

A

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

9
Q

What is the number one attribute contributing to puberty?

A

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

10
Q

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

A
  • Leptin-produced from fat, keeps us from eating
  • Insulin-store sugar
  • NPY
  • IGF-I
11
Q

List four external or social factors affecting puberty.

A

Season, Photoperiod, presence of the male, Rearing density

12
Q

Describe rearing density.

A

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

13
Q

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

A

LH and FSH

14
Q

How will prepubertal animals respond to exogenous FSH and LH?

A

Produces follicules and estradiol

15
Q

When does development of the hypothalamus occur?

A

Gradually as the animal grows

16
Q

What causes the preovulatory LH surge at puberty?

A

Preovulatory GnRH surge

17
Q

Describe how frequency of GnRH is controlled

A

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

18
Q

Where is the pulse generator at?

A

Preoptic area and anterior hypothalamus

19
Q

What is the Gonadostat Theory of Puberty?

A

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

20
Q

The hypothalams is inherently which gender?

A

female

21
Q

Which gender has a surge center?

A

Female because she doesn’t produce testosterone

22
Q

What must happen to testosterone to defeminize the hypothalamus.

A

It must be converted to E2

23
Q

Why is E2 prevented from crossing the blood brain barrier?

A

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

24
Q

What converts the testosterone to E2 after crossing the BBB?

A

aromatase enzyme

25
Q

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

A

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

26
Q

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

A

Age and amount of body fat

27
Q

How is environmental information received?

A

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

28
Q

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

A

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