endocrine embryology Flashcards
common component of all endocrine organs
mesodermal component which gives rise to vasculature
what gives rise to brain and spinal cord
neural ectoderm
what gives rise to the mouth
ectoderm- comprises the tissues as far back as the pharynx (the pharynx is endodermal origin) in th upper mouth. In lower mouth, ectoderm gives rise to tissues half way along the length of the tongue.
define stomodeum
mouth opening
origin of posterior pituitary
neural ectoderm evaginates at 4 weeks forming the posterior pituitary and central portion of infundibular stalk, plus the median eminence
origin of anterior pituitary
At 4 weeks, oral ectoderm from upper part of mouth evaginates forming rathkes pouch, and comes in contact with neural ectoderm. This pouch pinches off from oral epithelium and develops into anterior pituitary. The
Origin of the sella turcica
connective tissue which develops around the pituitary
origin of pituitary vasculature
local mesoderm infiltrates the pituitary giving rise to hypophyseal portal system and small vessels in posterior pituitary
Be able to describe the origins ofthe pars distalis, pars intermedia, pars tuberalis, pars nervosa and infundibular stalk.
pars tuberalis, intermedia and distalis are from oral ectoderm. Pars nervosa and infundibular stalk are from neural ectoderm
origin of thyroid follicle epithelial cells
endoderm
origin of calcitonin secreting cells in thyroid
neural crest- originally ectodermal
origing of thyroid vasculature
mesoderm
origin of parathyroid glandular cells
endoderm- inferior parathyroids from cleft btw 3rd and 4th pharyngeal pouches. Superior parathyroids from cleft after 4th pharyngeal pouch
describe thyroid gland formation
Medial evagination of endoderm btw first and second pharyngeal pouches forms (thyroid diverticulum) > the diverticulum enlarges and descends in the pharynx connected via the thyroglossal duct > the thyroid descends until in front of trachea > thyroglossal duct degenerates
what is the ultimobranchial body
group of cells that form just below the 4th pharyngeal pouch which gets populated by neural crest derived cells and cells that give rise to calcitonin secreting cells of thyroid.
How does the parathyroid and calcitonin cells become integrated into the thyroid
During the thyroids descent, it comes in contact with primordia of parathryoids and the ultimobranchial body, which both become embedded in the thyoid resulting in parathyroids and calcitonin releasing cells respectively
How does the cellular composition of the thyroid change
initially it is a solid mass of endodermal cells, but these get interspersed by infiltrating mesoderm into cords of cells (which will become follicular cells) then to small clumps which then form the epithelia of follicles
origin of adrenal cortex and medulla
Cortex arises from mesoderm (mesothelium between the dorsal mesentery and urogenital ridge) and medulla arises from ectoderm
Another name for urogenital ridge
wolffian body
describe development of the adrenal cortex
At 4 weeks, mesonephric or wolffian duct induces cells in the cleft btw dorsal mesentery and urogenital ridge to migrate into the mesenchyme dorsal to it > They form a cup structure > at 2-3 months another wave of clls from coelomic epithelium (mesothelium) enter the mesenchyme and surround the outer part of the cup
origin of the layers of the cortex
Reticularis: first round of cells that arrive from the coelomic epithelium. Fasciculata and glomerulosa: second group of cells that arrive from coelomic epithelium.
How does the adrenal cortex change after birth
a portion of the inner region of the early reticularis regresses. The layers of the fasciculata and glomerulosa become more distinct
development of adrenal medulla
Neural crest cells migrate to become sympathetic ganglia (sympathogonia) and some of them then migrate into the center of the cup.
Chromaffin cells
The early progenitors of the epi and NE producing cells of the medulla which migrate from the neural crest. They stain yellow brown with chrome salts
how does the adrenal medulla change after birth
It increases in volume.
