Endocrine Development

Question 1

All endocrine organs will have a ______ component that gives rise to vasculature. But not all will arise from ______.

Answer 1

Mesoderm

Endoderm

Question 2

Early in development, the neural tube and primitive brain arise from ______. And will become our ______/

Answer 2

neural ectoderm (ectoderm infolding that pinches off)

will become brain and spinal cord

Question 3

_____, a tubular arrangement of cells, gives rise to the majority of the digestive system.

Answer 3

Endoderm

Question 4

What gives rise to the upper part of the mouth back to the pharynx?

Answer 4

Ectoderm (which comprises the stomodeum - mouth opening)

• *note: pharynx is endodermal in origin and fuses with the ectoderm of the stomodeum
• ectoderm also gives rise to tissues halfway along length of tongue

Question 5

At what week does the primitive diencephalon form the beginning of the posterior pituitary and central portion of the infundibular stalk? How?

Answer 5

at 4 weeks
An EVAGination of the lower part of the neural ectoderm of the primitive diencephalon forms the beginnings of the posterior pituitary and central portion of the infundibular stalk.

Question 6

Rathke’s pouch

Answer 6

Oral ectoderm from the upper part of the mouth that evaginates (upward) and comes into contact with the neural ectoderm.

The anterior pituitary develops from the original oral ectoderm after it buds off and connects to neural ectoderm.

(remember we said the neural ectoderm forms the beginnings of the posterior pituitary and infundibular stalk)

• The pars distalis, intermedia, and tuberalis are all derived from rathke’s pouch

Question 7

Which time period does the pituitary take on a more typical shape of the gland?

Answer 7

3rd month

Question 8

Local mesoderm infiltrates the glandular/nervous tissue of the pituitary, giving rise to the ______

Answer 8

vasculature of the hypophyseal portal system and small vessels in the posterior pituitary.

Question 9

Embryologic cellular components of the thyroid

Answer 9

1. Endoderm
   - thyroid follicle epithelial cell
2. Neural crest
   - originally ectodermal
   - calcitonin secreting cells
3. Mesodermal
   - vasculature

All become embedded in the thyroid, but originate from different locations along the developing pharynx

Question 10

Thyroid development begins as?

Answer 10

Begins as medial EVAGination of the endoderm called the thyroid diverticulum
- begins to extend ~ between 1st and 2nd pharyngeal pouches

Question 11

Parathyroid development

Answer 11

Develop from cells INSIDE cleft between 3rd and 4th pouches, called the inferior parathyroid
and
From cells INSIDE cleft after the 4th pouch, called superior parathyroids

Question 12

Ultimobranchial body

• derived from
• gives rise to

Answer 12

derived from group of cells found in cleft after 4th pharyngeal pouch
(diff from superior parathyroids)

Gives rise to calcitonin-secreting or parafollicular cells of the thyroid.

Question 13

As the thyroid diverticulum enlarges and descends along the pharynx, it is attached via the _______. This structure typically degenerates, but _______ can develop if portions of it remains.

Answer 13

Thyroglossal duct

Thyroglossal cysts
can develop, or
thyroid may fail to descend properly.

Question 14

During the descent of the thryoid, it comes in contact with the primordia of the parathyroids that arise from the clefts between the ____ and ____ pharyngeal pouches, as well as the ______ body. These become embedded in the thyroid normally.

Answer 14

3rd and 4th

Ultimobranchial body

Question 15

Initially, the thyroid is a solid mass of _____ cells, but they get interspersed by infiltrating _____, that give rise to the vasculature that encircles each follicle.

Answer 15

Endodermal cells

Infiltrating mesoderm

Question 16

Origin of cortex vs medulla

Answer 16

Cortex: mesoderm

Medulla: ectoderm

Question 17

The initial primordium of the cortex originates from what? Describe the development of the cortex of the adrenal glands.

Answer 17

a group of cells of the coelomic epithelium (mesothelium) in a cleft btwn the region of the gut and the urogenital ridge.

4 weeks: cells of the coelomic epithelium proliferate and migrate into the mesenchyme just dorsal to it –> multiply and organize into cortex of the adrenal gland.
- reticularis of cortex

2-3 months: cells again proliferate from the coelomic epithelium at the same location and enter the mesenchyme (again) and surround the outer part of the cup
- fasciculata and glomerulosa

(cortex entirely mesodermal in origin)

Question 18

Describe the development of the medulla of the adrenal glands.

Answer 18

Neural crest cells (ectoderm) migrate to a region that become the sympathogonia (ultimately the sympathetic ganglia)

Some sympathogonia migrate to the center and becomes the medulary region of the adrenal gland.

Stains yellow-brown with chrome salts (chromaffin cells)

Question 19

Chromaffin cells

Answer 19

stains yellow brown with chrome salts

are the progenitors of epi and norepi cells of the medulla.