Pharyngeal pouches (!)
Endocrine glands - ductlessHormones released to circulationSpecific to target tissues Endocrine controlNeural controlp.505
Endocrine glands
Pituitary (hypophysis) - vertebrates
Neurohypophysis (posterior) - from the floor of brain (infundibulum)
Adenohypophysis (anterior)from pocket of embryonic mouth cavity
Pituitary development
HypothalmusAdenohypophysisNeurohypophysisoxytocin, ADHADH - Anti-diuretic hormoneincreased permeability in collecting ducts
Oxytocin - (mammals)uterine contractions, milk ejection
HypothalmusAdenohypophysisNeurohypophysisoxytocin, ADHLH, FSH, GH,prolactin, ACTHTSH Adenohypophysis - LH - Lutenizing hormoneFSH Follicle stimulating hormoneProlactin - mammaries, behavior
NeurohypophysisOxytocin
Reproductive hormones
Primary follicleoocyteFollicle cellsLooking within the ovaryFSH - causes follicle to mature, growFollicle cells secrete estrogenEstrogen promotes development of endometrium
promotes LH release when estrogen is high positive feedbackEstrogen
Surgical photos capture ovulation occurring
Induced ovulatorsLH not promoted by estrogen
Act of breeding stimulates pituitary gland to release LH
Llamas: Levels of LH in the blood begin to rise 15 minutes after the beginning of breeding.
Follicle remains as corpus luteum (mammals, reptiles, sharks)releases progesterone and estrogenProgesterone continues growth of endometrium blood vessels, decrease contractionsPromotes egg layers, shell in reptiles
FollicleremainsIf fertilization: blastocyst chorionic gonadotropin which maintains c. luteumEventually, placenta takes over progesterione prodn
Fertilization
corpusluteum
CGProgesterone and estrogen also inhibit FSH, LH and prepare mammary glands
At birth, decreased levels of progesterone promotes oxytocin, prolactin
Feedback from mammaries Stimulates prolactin, oxytocin releaseInhibits GnRH and FSH
p.685
Suckling feedback allows for embryonic diapauseMother has blastocyst, yet prolactin inhibits corpus luteum, thus progesterone
Marsupials
Kangaroo is pregnantShould I develop or not?After weaning (or young dies), suckling decreases, blastocyst can implantmarsupial breeding
MarsupialsMarsupials - most development during lactationEasier to terminate parental care
Placentals cannot readily terminate
vs.