Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

REPRO > Puberty and seasonality > Flashcards

Puberty and seasonality Flashcards

1
Q

Compare the hypothalamus of the male and female

A
  • Female has surge and tonic centre

- Male has no surge centre

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Describe the post-puberty LH release in males and females

A
  • LH surges in females every ~20 days, lower amplitude higher frequency pulses in between peaks
  • In male have consistent episodic pattern
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What stimulates the release of FSH and LH from the pituitary?

A

GnRH from the hypothalamus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is the benefit of seasonal breeding?

A

Ensures offspring are born when there is optimum survival

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Describe anoestrus in the female in the non-breeding season

A
  • No oestrus cycle
  • Ovaries inactive
  • Due to decreasing GnRH, LH and FSH
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What stimulates the termination of anoestrus in long day breeders?

A
  • Lenghtening daylight hours

- Increasing plane of nutrition

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What stimulates the termination of anoestrus in short day breeders?

A

Shortened daylight hours

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What are the seasonal effects on the male?

A
  • Low testosterone production
  • Reduced or cessation of sperm production
  • Reduced sperm motility
  • Testes involute
  • Willingness to breed may change
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Define puberty

A

The developmental process to transform the individaul into one capable of reproducing

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What types of changes take place during puberty?

A
  • Endocrine

- Morphological

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What happens to the hypothalamus at puberty?

A
  • Change in activity of higher pre-synaptic neuones
  • Stimules GnRH neurones
  • Leads to GnRH secretion
  • Which in turn stimulates the gonadotrophins initiation gametogenesis, steroidogenesis and reproductive tissue development
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Describe the hypothalamus of the female following puberty

A
  • Surge centre present
  • Controls pre-ovulatory surge in GnRH, leading to pre-ovulatory surge in LH
  • Tonic secretions also at higher level due to frequency of secretion increasing
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Describe the pre-pubertal HPG axis in the female

A
  • Tonic centre stimulates LH pulses
  • Low frequency of GnRHpulses, not enough for LH and FSH release at high levels
  • Oestradiol secretion by ovarian follicles low
  • Cannot stimulates GnRH neurones in surge centre
  • Low leves of E2 have negative feedback on tonic centre - little GnRH release
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Describe the transition to puberty in the HPG axis of the female

A
  • Negative fedback effect of low E2 levels reduced
  • Allows tonic centre to produce GnRH, increase in GnRH and thus increase in FSH and LH
  • Increases E2 further, increases FSH and LH and more E2
  • Eventually enough E2 to stimulate the surge centre
  • i.e. trigger for puberty onset is loss of -ve feedback to tonic centre
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Describe the HPG axis in male puberty onset

A
  • Pre-puberty testosterone/oestradiol have negative feedback to GnRH
  • GnRH neurones less sensitive to -ve feedback, GnRH increased, LH and FSH increased
  • Puberty occurs
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is the average age for puberty in the male and female sheep?

A

Male:7 (6-9) months
Female: 7 (4-14) months

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What is the average age for puberty in the male and female cow?

A

Male: 11 (7-18) months
Female: 11 (9-24) months

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What is the average age for puberty in the male and female horse?

A

Male: 14 (10-24) months
Female: 18 (12-19) months

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What is the average age for puberty in the male and female pig?

A

Male: 7 (5-8) months
Female: 6 (5-7) months

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What is the average age for puberty in the male and female dog?

A

Male: 9 (5-12) months
Female: 12 (6-24) months

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What is the average age for puberty in the male and female cat?

A

Male: 9 (8-10) months
Female: 8 (4-12) months

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What is the main factor that influences seasonality?

A
  • Melatonin and its effect in each species

- Influenced by photoperiod adn nutrition

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Outline melatonin secretion

A
  • Depends on photoperiod
  • Sensed by retina and hypothalamus (
  • Declining light (increased dark) increases melatonin secretion from the pineal gland
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What is the effect of melatonin in short day breeders?

A

Stimulates reproduction, is stimulatory to GnRH release

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

What is the effect of melatonin in long day breeders?

A

Represses reproduction, is inhibitory to GnRH release

26
Q

Describe melatonin secretion in short day breeders

A
  • Nerve tract in retina stimulated by light
  • Signal to hypothalamus at suprachiasmatic nucleus to going to superior cervical ganglion
  • Nerve to pineal gland
  • Stimulates inhibitory neurone which inhibits melatonin release
  • Elevated activity in neurones, but inhibited melatonin release
  • Opposite in cyclicity: less light, less stimualtion, more melatonin, GnRH release
27
Q

Describe the role of kisspeptin neurones in seasonality

A

Kisspeptin stimulates GnRH release, FSH and LH release

28
Q

Where are RFRP neurones found?

A

Within the hypothalamus

29
Q

Describe the role of the RFRP neurones in seasonality

A
  • RFRP neurones (amide related peptide) release RFRP3
  • In long day breeder, RFRP3 stimulates neurones producing kisspeptin, stimulates GnRH release, FSH and LH release = cyclicity
  • In short day breeders, RFRP3 inhibits kisspeptin neurones, low kisspeptin, low GnRH, FSH and LH
30
Q

Give examples of factors that influence puberty

A
  • Body size
  • Nutrition
  • Season born
  • Photoperiod experienced at puberty
  • Presence/absence of opposite sex just prior to puberty
  • Density of same sex groups
31
Q

Explain the role of body size in female puberty

A
  • Amount of fat
  • GnRH neurones sensitive to metabolic status
  • 3 main types of pre-synaptic neurons affecting GnRH release
  • Leptin, fatty acids and glucose thought to promote activity in kisspeptin neurones
  • When threshold of “fatness” has been acheived, triggers signal from kisspeptin neurone to GnRH neurone, triggering GnRH release
32
Q

Explain the role of nutrition on female puberty

A
  • Higher plane of nutrition leads to earlier puberty, but over conditioned not ideal for breeding
  • Moderate has later puberty onset but better for pregnancy and parturition
  • Low plane has later puberty onset but may not be able to maintain pregnancy
33
Q

How does leptin promote activity in kisspeptin neurones?

A
  • Leptin produced by adipose tissue
  • Acts on neuropetide Y neurones
  • Synapses to kisspeptin neurones
34
Q

Give strategies that can be used to advance/delay puberty/seasonality in domestic animasl

A
  • Nutrition
  • Hybrid vigour
  • Photoperiod
  • Endocrine studies (mostly experimental)
  • Melatonin
  • GnRH administration
  • FSH/LH e.g. pregnant mare serum gonadotrophin
  • Progesterone
35
Q

Give a disadvantages of using GnRH to control puberty/seasonality

A

In deep anoestrus, pituitary will not be responsive to GnRH so would be pointless

36
Q

Briefly outline the use of progesterone to advance seasonality in domestic animals

A
  • In combination with PMSG
  • Mimics luteal phase
  • Stimulates follicles to get to maturation
37
Q

Describe the HPG axis in long day breeders during the breeding season (female)

A
  • Less melatonin produced
  • Has stimulatory effect oon GnRH release
  • GnRH release from hypothalamus, FSH and LH increased
  • Increased inhibin production, shift from FSH to LH dependent
  • Estradiol has positive feedback at certain level causing LH surge
  • Progesterone from CL after ovulation suppresses GnRH release, suppresses axis
38
Q

Describe the mare’s transition from winter anoestrus

A
  • Takes 5-60 days
  • Irregular oestrus
  • Transition follicles present
  • Ovulation will not occur until steroidogenic competence has increased through folliculogenesis stimulated by FSH
39
Q

When do uterine involution and resumption of ovarian activity occur in the beef cow?

A
  • Involution: 30 days

- Resumption: 50-60 days

40
Q

When do uterine involution and resumption of ovarian activity occur in the dairy cow?

A
  • Involution: 35-45 days

- Resumption: 18-25 days

41
Q

When do uterine involution and resumption of ovarian activity occur in the bitch?

A
  • Involution: 90 days

- Resumption: 135 days

42
Q

When do uterine involution and resumption of ovarian activity occur in the ewe?

A
  • Involution: 30 days

- Resumption: 180 days

43
Q

When do uterine involution and resumption of ovarian activity occur in the mare?

A
  • Involution: 14 days

- Resumption: 5-12 days

44
Q

When do uterine involution and resumption of ovarian activity occur in the queen?

A
  • Involution: 30 days

- Resumption: variable

45
Q

What is ovarian rebound?

A

The return to cyclicity post-partum

46
Q

Describe gestational anoestrus

A
  • Prolonged high progesterone (CL or placental)
  • Suppression of HPO axis
  • Fewer follicular waves and no ovulation (except mare)
  • Occasional oestrus behaviour
  • Increased uterine size
47
Q

What hormonal events occur following parturition?

A
  • Decline in parturition

- Transient increase in oestrogens

48
Q

What are some of the important post-partum events?

A
  • Uterine involution
  • Endometrial repair
  • Expulsion of lochia
  • Lactation/suckling
  • Ovarian rebound
49
Q

Describe the ovarian rebound mechanism

A
  • Re-initiation of HPO axis (pit responds to GnRH again)
  • Follicular wave emergence
  • Resumption of full ovarian activity (increased sensitivity to GnRH, increased oestradiol, Increased LH pulse frequency, ovulation, short oestrus cycle)
50
Q

What are the 2 main influencers of ovarian rebound?

A
  • Uterus

- Metabolism

51
Q

Describe the changes in hormonal balance pre and post calving

A
  • Pre: increased oestradiol
  • Post: decreased oestradiol and progesterone
  • Following ovulation have increased progesterone
  • As follicles develops, increased LH pulse frequency and then ovulation
52
Q

What stimulates return to cyclicity in the sow?

A

Weaning

53
Q

What factors influence ovarian rebound?

A
  • Season
  • Type of breeder e.g. seasonal, monooestrus
  • Suckling
  • Peri-parturient abnormalities (persistent CL)
  • Milk yield/nutrition (NEB)
  • Parity (esp primiparous)
54
Q

What may cause extended anoestrus post-partum?

A
  • Lactation
  • Season
  • Melatonin levels
55
Q

How does lactation lead to extended anoestrus post-partum?

A
  • Prolactin
  • Prevents pregnancy before weaning
  • Mammary stimulation/suckling suppresses GnRH
  • Offspring influences e.g. visual, olfactory, auditory
  • Weaning promotes GnRH/LH secretion
56
Q

Describe ovarian rebound in the mare

A
  • Rapid onset
  • Rapid uterine involution
  • Deteectable ovary activity within 2 days
  • Foal heat - can establish pregnancy in this time
  • Can be delayed
57
Q

What may delay ovarian rebound in the mare?

A
  • Season (foaling late in season)
  • Maternal instinct (silent oestrus)
  • “foal shy”
58
Q

Describe ovarian rebound in the sow

A
  • Suckling/weaning important
  • Early follicular activity
  • Prolactin suppresses LH = no ovulation
  • Affected by length of lactation
  • Weaning initiates LH surge within 7 days
59
Q

Describe ovarian rebound in cats

A
  • Oestrus inhibited often by lactation but is not uniform
  • Anoestrus 2-8 weeks post-weaning
  • Early weaning = early oestrus
60
Q

Describe ovarian rebound in dogs

A
  • Period of reproductive quiescence, not lactation dependent
  • Around 135 days
  • FSH/LH/oestrogen rise in late anoestrus
  • Strongly influenced by nutrition
  • Increased E2 at end of anoestrus
  • Suppress FSH, shift to LH dependency, more E2
  • Declines following ovulation
61
Q

What cycling abnormalities can occur following parturition?

A
  • Delayed onset of cyclicity
  • Cessation of ovarian activity following initial resumption
  • Ovarian pathologies e.g. follicular/luteal cysts, persistent CL

REPRO (30 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions