Sexual Maturation In Females Flashcards
Puberty/Sexual maturation
Gradual acquisition of reproductive competence
Why does maturation occur?
Due to increased GnRH secretion and increased sensitivity of hypothalamic-pituitary gonadal (HPG) cells to hormonal stimulation
What does puberty depend on?
Maturation of repro tract and is influenced by genetics and environment (nutrition, health, psychosocial aspects and photoperiod)
First Ovulation
Normally occurs without estrus, followed by formation of CL and increase in P4
First Luteal Phase
P4 from first CL primes brain for future sensitivity to E2 which will later induce first behavioral estrus when second ovulation occurs
First Behavioural Estruss
Precedes second ovulation and involves estrus behaviour
Estradiol
Has strong negative feedback on hypothalamus which reduces over time as a female matures, until it flips at puberty and becomes positive feedback
GnRH pusatility
Increases over time as E2 feedback becomes less negative and then positive
Does body weight or age have a greater influence on puberty?
Body weight
Nutrition influences reproduction through…
Its influence on blood concentrations of leptin, FA and glucose
Leptin
Released from fat stimulates kisspeptin neurons which stimulate GnRH neurons to release GnRH
Ghrelin
Released from GI tract when energy is insufficient, inhibits kisspeptin neurons
Other influences of GnRH Secretion
Olfactory recognition of pheromones and photoperiod
Do gilts mature faster in small or large groups?
Large groups, also mature faster when exposed to mature males
In long photoperiods
Light stimulates SCN in hypothalamus - signals superior cervical ganglion - signals pineal gland to decrease NE and melatonin secretion
