Exam 2 Flashcards
Alpha fetal protein is found in the blood of both male and female fetuses and binds tightly to estradiol, preventing it from crossing the blood-brain-barrier in female fetuses and inactivating the GnRH surge center in the hypothalamus
T
External factors such as stress can modulate the function of presynaptic neurons in the hypothalamus which can reduce the secretion of GnRH from neurosecretory cells in the tonic release center
T
In the female, the onset of puberty is a result of a progressive decrease in hypothalamic sensitivity (tonic GnRH release center) to the negative feedback effects of estradiol
T
In the prepubertal female, the GnRH surge center of the hypothalamus is unable to stimulate a preovulatory surge release of LH from the anterior pituitary due to the lack of preovulatory size follicles on the ovaries
T
There is evidence that the initiation of high frequency low amplitute GnRH pulses can be advanced by exposure to increased glucose and/or fatty acids concentrations in the blood
T
The anterior pituitary of a prepubertal female is unable to secrete significant amounts of FSH and LH even if stimulated by exogenous GnRH
F
Circulating Leptin is directly related to body fatness and may function to inform the GnRH secreting neurons of the nutritional status of the female
T
Fall (September- October) born lambs receiving adequate nutrition reach puberty 5-6 months, while spring born lambs reach puberty at 10-12 months
F
Prepubertal gilts housed in larger groups (>10 gilts) exhibit delayed puberty while prepubertal gilts housed in small groups (2-3 gilts) reach puberty at the expected time
F
Presence of a male will reduce age at puberty in prepubertal gilts or heifers
T
In the sheep, low melatonin produced by the pineal gland during the spring and summer results in low kisspeptin secretion resulting in reduced GnRH secretion by the tonic release center of the hypothalamus, resulting in anestrus
F
In the beef cow, 3 or more suckling bouts by her offspring per day are required to keep blood LH low and to maintain lactational anestrus
T
The follicular phase in the women occupies only 20% of the length of the menstrual cycle, while in the cow it only occupies 50%of estrous cycle length
F
Lactating women on a high plane of nutrition return to cyclicity sooner postpartum than lactating woman on a low plane of nutrition
T
In the postpartum rabbit, prolactin is no longer released in response to suckling after 30 days of lactation, and the mother leaves her offspring at that time to fend for themselves
T
Exhibits clusters of estrous cycles during the spring and summer only
seasonally polyestrus (long day breeder) mare
uniform distribution of estrous cycles throughout the year
polyestrus
pig
exhibits one estrous cycle per year
monoestrus
wolf
exhibits clusters of estrous cycles during the fall and winter only
seasonally polyestrus (short day breeder) sheep
An implant containing melatonin during anestrus will initiate early cyclicity in this specie
sheep
An implant containing a melatonin antagonist during anestrus will initiate early cyclicity in this specie
mare
Regu-mate (altrenogest) is a progesterone that was developed as a estrous synchronizing agent in these 2 species
mare
pig
increases collegians activity by theca internal cells (degrades tunica albuginea forming stigma)
progesterone
increased follicular blood flow and fluid uptake
prostaglandin E2 (PGE2) and histamine
increases contraction of ovarian smooth muscle and releases lysosomal enzymes from the granulose cells to further weaken the follicular wall for oocyte expulsion
prostaglandin F2a