2.5 Puberty and Maturity

Question 1

Puberty:

Answer 1

Is the period when the endocrine and gametogenic functions of the gonads have 1st developed to the point where reproduction becomes possible

Question 2

puberty in females is defined as

Answer 2

the age at which they first express estrus with ovulation

Question 3

In heifers, puberty has been defined as

Answer 3

the first estrus that is followed by a normal luteal phase

Question 4

puberty =

Answer 4

a state of transition

Question 5

Collective t​erm that describes puberty:

Answer 5

• physiological
• behavioral
• morphological​/anatomical changes

**leads to the transformation of the infertile juvenile to the potentially fertile adult

Question 6

physical changes associated with puberty: Female

Answer 6

• mammary development
• growth of external genitalia
• alterations in body proportion

Question 7

physical changes associated with puberty: male

Answer 7

• growth of testis
• growth of the ​penis
• more muscle

Question 8

muscle growth in males is due to?

Answer 8

testosterone

Question 9

puberty behavioral changes: male

Answer 9

male mounts female

Question 10

puberty: behavioral changes: female

Answer 10

the ​female comes into behavioral oestrus and will stand to be mounted

Question 11

endocrine changes​: prepubertal period:

Answer 11

low gonadal steroid secretion but the hypothalamus is also sensitive​ to negative feedback, so Gonadotrophin (GT) secretion is low

Question 12

endocrine changes: approaching puberty

Answer 12

sensitivity to negative feedback decreases and GTs start to rise

• pulsatile secretion of GnRH increases to 1/h; drives an increased LH pulse frequency
• steroidal response to each LH pulse rises as gonads mature
• Female develops the ​ability to positive feedback response to rising oestradiol and so triggers the first LH surge

Question 13

Factors that effect​ the timing of puberty:

Answer 13

1. photoperiod (light sensitive) / season​ (seasonal reproduction)
2. genotype
3. social cues
4. nutrition/ growth​ rate

Question 14

Photoperiod: spring born​ lambs ovulated for the first time in

Answer 14

autumn age 26-35 weeks

Question 15

Photoperiod: Autumn-born lambs ovulated for the first time in

Answer 15

autumn age 48-50 weeks

Question 16

Photoperiod: autumn born lambs kept in reverse photoperiod ovulated for the first time in

Answer 16

summer age 33-37 weeks

Question 17

genotype: cattle

Answer 17

-dairy earlier than beef
- high yielding earlier puberty than lower yielding

Question 18

genotype: dogs

Answer 18

– small breeds 6-10 months
– medium-sized​ breeds 9-14 months
– large breeds 18-20 months

Question 19

At what age are heifers frist serviced around?

Answer 19

15 months

Question 20

at what age are heifers fat 1st calving?

Answer 20

24 months

Question 21

___ can delay puberty and breeding?

Answer 21

poor growth

Question 22

without kisspeptin:

Answer 22

You will not have LH, FSH, or puberty

Question 23

What is required for Kisspeptin?

Answer 23

GPR54

Question 24

Which is more severe? deletion of kisspeptin or GPR54?

Answer 24

GPR54 because you cant have kisspen without GPR54

Question 25

2 sources of kisspeptin?

Answer 25

1. preoptic area kisspeptin neuron 2. Arcuate kisspeptin neuron

Question 26

Preoptic area kisspeptin neuron:

Answer 26

important for initial LH spike

Question 27

arcuate kisspeptin neuron:

Answer 27

important to maintain LH spike

Question 28

Do kiss neurones have leptin receptors?

Answer 28

yes

Question 29

Describe changes in the activities of key hormones, namely, estradiol and progesterone, LH and FSH as well as prostaglandin: (a) before – (b) during – (c) after –

Answer 29

(a) before – little or no HPG activity (b) during – increasing gonadotrophin secretion due to increased hypothalamic GnRH secretion and (c) after – adult pattern of gonadotrophin secretion – male constant, female cyclical the onset of puberty