Reproduction - puberty Flashcards
What is reproduction?
The endocrine and gametogenic functions of the gonads develop to the point where reproduction is possible
What happens to females during puberty?
Mammary development
Growth of external genitalia
Alternations in body proportions
Behavioural oestrus e.g. standing to be mated
Growth spurt
What happens to males during puberty?
Growth of testes
Muscle development
Mountin behaviour
Growth spurt
What are the endocrinological changes of puberty?
Hypothalamus becomes less sensitive to GnRH so the negative feedback is reduced. This means pulsatile secretion of GnRH increases and drives increase of LH pulses.
What affects the onset of puberty?
Photoperiod
Genotypes
Social cues
Nutrition and growth rate
How does photoperiod affect puberty?
Spring lambs come into puberty earlier than autumn lambs (26-35 weeks compared to 33-37 weeks)
How does dog size affect puberty?
Smaller dogs come in earlier than large dogs
How do social cues affect pubertty?
Addition of a male can bring the advancement of puberty
How does nutrition affect puberty?
Heavier animals come into puberty earlier
What is the gonadostat hypothesis?
At 8 years old the hypothalamus increases GnRH production
This triggers LH/FSH release
Test/E2 is then released
What is the hypothalamus is king theory?
The kisspeptin/NKD/DYn neurons form a neural arc
NKB/NK£ signalling accelerates
Dyn/KOR signalling breaks activation of the neural arc
This generates rhythmic oscillation of neural activity, inducing pulsatile release of kisspeptin and release of GnRH
What are seasonal breeders?
Same time each year. Example are sheep, horses, goats, deer, cats, wild pigs, hamsters and rabbits
What are opportunistic breeders?
When the opportunity presents itself. Examples are dogs, cow, pigs, guinea pigs and rodents
How does light affect the pineal gland?
Photic stimuli are released from the retinal ganglion via retinohypothalamic tract
Travels to suprachiasmatic nucleus in the anterior hypothalamus
Travels via peripheral and central sympathetic neurons and the superior cervical ganglion to pineal gland
Less melatonin is produced
What does less melatonin production do?
In short day breeders: this reduces kiss > less GnRH > no cycle
In lond day breeders: increases kiss > more GnRH > cycle
