T4: Puberty Flashcards
what is the main difference within hypothalamus for male and female
aFP which is secreted by the yolk sac, binds to estrogen in the female (preventing entry), surge center develops
-in the make testosterone enters and is converted to E2, surge center is defeminized and does not develop
what is puberty
the ability to accomplish reproduction successfully or the period during which adolescents reach sexual maturity and become capable of reproduction
what does needs to be developed to property respond to puberty
need the hypothalamus/ neurons to respond to signals to have sufficient stimulation
what is prepubertal
before the onset of puberty
define peripubertal
around the time of the onset of puberty
define precocious puberty
early onset of puberty
what are the five things that define puberty in the female
- Age at first ovulation: typically 1st ovulation is “silent” / verified by ultrasound, rectal palpation, hormone assays
- age at first estrus: outward behavioral signs
- age at which female can support pregnancy without harm
- age at mammary development/vulva development (vaginal opening in mice)
- Age at hormonal detection (LH/FSH)
what is the age for pubertal onset in bovine
m: 11 months F: 11 months
what is the age for pubertal onset in canine
M:9 F:12
what is the age for pubertal onset in equine
M:14 F:18
what is the age for pubertal onset in feline
M:9 F: 8
what is the age for pubertal onset in ovine
M:7 F:7
what are the three factors influencing puberty
- body size: fat deposits: need sufficient leptin hormone levels
- Social/eternal factors
-exposure to male
-the season of birth
-photoperiod of during pubertal onset
-number of same-sex animals in enclosures - Breed
what is the % maturity at puberty for dairy
30-40
what is the % maturity at puberty for beef
55-65
what is the % maturity at puberty for sheep
40-63
what is the main driver for social impacts
pheromones: help growth of hypothalamus
what are the environmental impacts for puberty
(seasonal) the month of birth will influence age at puberty in seasonal breeders
-spring lambs enter puberty 5-6 mo
-fall lambs enter 10-12 mo
- heifers born in autumn reach puberty earlier than spring-born heifers
what are the five factors that define puberty in the male
- age when behavioral traits are expressed (mounting, erections)
- Age at first ejaculation
- Age when spermatozoa first appear in the ejaculate
- Age when the ejaculate contains a threshold number of spermatozoa
- age when ejaculate has normal spermatozoa (cytoplasmic droplet detection)
what are the factors in a BSE
- Physical exam
- Scrotal circumference (min based on breed?)
- Sperm motility : more than 30%
- Sperm morphology: more than 70% normal
what are the two main factors in hypothalamus modifications
- E2 inhibits GnRH synthesis and secretion at low levels
-the hypo. will be modified over time (as puberty is obtained) to respond in positive manner to E2 (think surge center)
what are the hypothalamus modifications for the female
-still producing follicular waves, just in smaller amounts
-the surge center will lie dormant bc of insufficient E2 produced from the ovaries
-the tonic center is highly sensitive to low levels of E2, and will inhibit GnRH synthesis
-transition of less sensitivity= less suppression= more GnRH
what are the hypothalamus modifications for the male
-more GnRH neurons will become less sensitive to negative feedback as puberty approaches (peripubertal period)
-less negative feedback = more steroid hormones
what are the hypothalamus modifications for the male
-more GnRH neurons will become less sensitive to negative feedback as puberty approaches (peripubertal period)
-less negative feedback = more steroid hormones
what are the signals acting on KNDy neurons
-blood glucose
-blood leptin
-blood fatty acids
what are the KNDy neurons
kisspeptin, neurokinin B(+), Dynorphin (-)
what does E2 not have
no receptors on GnRH neurons, E2 does not directly effect GnRH neurons
describe the surge generator
medial preoptic area: Kisspeptin neuron to GnRH neuron releases GnRH/LH surge from the pituitary to the ovary.
-estrogen plays a positive feedback role to the hypothalamus
describe the GnRH Pulse generator
arcuate nucleus: kisspeptin neurons to GnRH neuron releases GnRH/LH pulses onto the ovary
-estrogen plays a negative feedback
what are the puberty requirements in females
-fully functioning tonic center
-fully functioning surge center (cause GnRH/LH surge for ovulation
during puberty, females are unable to produce ______to stimulate the surge center
enough estrogen
what are the main feedback mechanisms for puberty
-pubertal transition, negative feedback of estrogen is decreased and more GnRH is produced
-more GnRH increased LH pulses, increased estrogen from ovary, positive feedback and massive release of GnRH ovulation
when will puberty be initiated
when GnRH neurons are able to fully respond to positive and negative feedback
what can also contribute to puberty
management practices, exogenous hormones can help initiate
what hormones inhibits the initiation of pubertal inset in males and females
estrogen
what neuron does not make up one of the KNDy neurons
neurophysin
season influences pubertal status regardless of species
true
what morphological assessment of sperm can be used to identify if a male is pubertal
presence/ absence of cytoplasmic droplet
regardless of species, females become pubertal sooner than males
false, usually males `
