Lecture 13 and 14: Reproductive Endocrinology: Estrous Behaviour and Puberty in the Female

Question 1

feedback on hypothalamus

Answer 1

gonadotropins in the pituitary respond to GnRH secreting FSH and LH, which go to peripheral circulation

progesterone from corpus luteum negatively feeds back to surge center and there is NO GnRH released

estradiol is released from ovarian follicle and positively feeds back to surge center and there is an increase in pulsatility of the GnRH and eventually a surge

Question 2

Characteristics of Estrous and Behaviour

Answer 2

sexual receptivity, increasef physical activity, mounting activity

other signs: mucous vaginal discharge, swelling and reddening vulva, bellowing, restlessness, trailing other females, lordosis

Question 3

Puberty

Answer 3

acquisition of reproductive competence (gradual process)
highly dependent on the production of GnRH by the hypothalamus
the sensitivity of HPG cells to hormonal stimulation and feedback changes
required for delivery of oocyte
influence by:
-genetics
environments
- nutrition
- health
- social
- photoperiod

Question 4

Definition of puberty in females

Answer 4

first ovulation

• with or without estrus - first ovulation normally is not preceded by estrus
• formation of CL and increase in progesterone

confirmation of CL

• rectal palpation, ultrasound laparoscope
• progesterone concentrations

Question 5

Age at puberty influenced by

Answer 5

GENETICS: early maturing breeds have earlier onset of puberty than late maturing breeds , maternal breeds reach puberty earlier than ,meat type breeds

BODY WEIGHT

• more important than age
• bigger animals have puberty younger

PUBERTY IS HIGHLY CONTROLLED BY METBOLISM

• hypothalamic neurons sense and transmit metabolic information that control gonadotropin releasing hormone secretion
• when low nutrient availability –> there is less GnRH secretion
• other neuron clusters in the hypothalamus sense metabolic molecules and influence GnRH secretion

NUTRITION

• low plan = late puberty
• high plane = early puberty

SOCIAL CUES
- olfactory recognition of pheromones

PHOTOPERIOD

• some species are seasonal breeders
• pineal gland activity