Endocrine Histology and embryology

Question 1

1. Describe the overall structures and subdivisions of the pituitary, thyroid, parathyroid and adrenal glands.

Answer 1

pituitary

• has an anterior part (pars distalis) which is associated with pars tuberalis
• has a posterior part (pars nervosa)
• and an middle part (pars intermedia)
• the neck is called the infundibulum
• it hangs down from the median eminence of the hypothalamus

thyroid

• made up of follicular cellswhich take up iodide–>iodine and secrete thyroglubulin into the colloid which then cleaves off T3 and T4
• scattered around are parafollicular cells that produce calcitonin
• and parathyroid tissue is mixed in

Adrenal

• has a 3 layered cortex
• -zona glomerulosa
• -zona fasiculata
• -zona reticularis
• has a medulla
• and has an outer capsule

Question 2

2. Describe the hormones and/or classes of hormones associated with each region or zone of the glands.

Answer 2

pituitary-

• ant pit- ACTH, FSH, TSH, LH, Prolactin, GH
• Post Pit- ADH, oxytocin

adrenal-

• zona glomerulosa- minerlaocorticoids
• zona fasiculata- glucocorticoids
• zona reticularis- androgens
• Medulla- catecholamines

Thyroid-

• follicular cells/ colloids- T3, T4
• parafollicular cells- calictonin
• parathyroids cells- parathyroid hormone

Question 3

3. Name the specific blood vessels running into and out of the glands.

Answer 3

pituitary-
-superior and inferior hypophyseal artery

adrenal
- suprarenal artery, medullary vein–>suprarenal vein

Thyroid

• Suprathyroid artery and vein
• infrathyroid artery and vein

Question 4

4. For the anterior pituitary, describe the relationship of pituitary cells relative to the neurosecretory cells of the hypothalamus and the arrangement and importance of the hyphophyeal portal system, and describe why this overall arrangement is so crucial to their function(s).

Answer 4

neurosecretory cells are in the medain eminence of the hypothalamus, they release releasing factors into the hypophyseal portal system which then goes through the pars tuberalis to the anterior pituitary

Question 5

5. For the thyroid, describe the arrangement and structure/function of the epithelial cells, the colloid and the calcitonin-releasing cells, and describe why this overall arrangement is so crucial to their function(s).

Answer 5

1

Question 6

6. For the parathyroid, be able to differentiate the parathormone-releasing cells, the oxyphil cells, and adipose cells, characterize the basic arrangement of cells relative to each other and to blood vessels in these glands.

Answer 6

1

Question 7

7. For the adrenal cortex, be able to discriminate the three layers of the cortex as well as the subcapsular arterial plexus and the medullary sinusoidal region, and describe the types of cells in each region and what they release and whether or not they respond to ACTH.

Answer 7

the three layers of the cortex respond to ACTH

• zona glomerulosa- minerlaocorticoids
• zona fasiculata- glucocorticoids
• zona reticularis- androgens

Question 8

8. For the posterior pituitary, describe axonal transport and the mechanism of release of its relevant hormones.

Answer 8

ADH and Oxy tranported from hypothalamus down axon cell bodies to herring bodies in post pit. and released in to capillaries

Question 9

9. For the adrenal medulla, define any innervation and explain what the endocrine cells in the adrenal medulla respond to.

Answer 9

sympathetic stimulation

Question 10

10. For the pituitary gland, describe the origins of the anterior and posterior pituitary and vasculature. Define stomodeum, Rathke’s pouch, sella turcica, and the difference between neural ectoderm and oral ectoderm. Describe the origins of the pars distalis, pars intermedia, pars tuberalis, pars nervosa and infundibular stalk.

Answer 10

posterior pituitary comes from neural ectoderm

anterior pituatary comes from oral ectoderm (rathkes pouch)

stomadeum- invagination in oral ectoderm

sella turcica- where pituatary sits

pars tuberalis- oral ectoderm
pars distalis- oral ectoderm
infundibular stalk- neural ectoderm
pars nervosa- neural ectoderm
pars intermedia

Question 11

11. For the thyroid, describe which portions of the pharynx it originates from, detailing the initial origins (endoderm, ectoderm, mesoderm) of the cells that will make up the thyroid follicular cells, calcitonin cells and blood vessels, explaining how the calcitonin cells become incorporated into the thyroid gland during development, and defining the thyroid diverticulum, the thyroglossal duct, descent of the thyroid, the ultimobranchial body and the pyramidal lobe of the thyroid.

Answer 11

thyroid diverticulum of the endoderm in b/n the pharyngeal pouches. thyroglossal duct is the extenion of the thyroid diverticulum

calctitonin cells- come from neural crest and ultimobranchial body

parathyroid cells- parathyroid primordia b/n 3rd and 4th pharyngeal pouches and the after the 4th pharnyngeal pouch

Question 12

12. For the parathyroids, describe which portions of the pharynx they originate from, detailing the initial origins (endoderm, mesoderm) of the cells that will make up the blood vessels and parathyroid cells and explaining how the parathyroids become embedded onto the thyroid gland during development.

Answer 12

parathyroid cells- parathyroid primordia b/n 3rd and 4th pharyngeal pouches and the after the 4th pharnyngeal pouch (endoderm)

Question 13

13. For the adrenal glands, describe the origin and migration(s) of cells that will make up the zona reticularis, zona fasciculata and zona glomerulosa. Describe the origin and migration of cells that become the medulla. Define the terms urogenital ridge, neural crest, sympathogonia and chromaffin cells.

Answer 13

from urogenital ridge mesothelial cells (reticularis) migrate doraslly to meet up with chromaffin cells medulla( neural crest) that are migrating ventrally

at 2-3 months there is a second wave of mesothelial cells (fasiculata and glomerulosa) that surround the two layerd ball to creater