Endo Development Flashcards
Pituitary gland precursor
Ectoderm
Thyroid gland precursor
Endoderm
Parathyroid gland precursor
Endoderm
Adrenal gland precursor
Mesoderm
Whats the difference between how exocrine and endocrine glands form??
Exocrine –> Epithelium maintains connection with epithelium and forms duct and secretory components
Endocrine –> loses its connection with epithelium of origin, forms rich capillary plexus; release hormones early in the fetal period
What are the two ectoderm primordial that form the pituitary gland?
Oral ectoderm - Hypophyseal diverticulum/Rathke’s pouch
Neural ectoderm - Infundibulum
Hypophyseal diverticulum (Rathke’s Pouch) anterior wall becomes…
distal lobe of pituitary
Hypophyseal diverticulum (Rathke’s Pouch) superior extension becomes…
tuberal lobe of pituitary
Hypophyseal diverticulum (Rathke’s Pouch) posterior wall becomes…
intermediate lobe of pituitary
What forms the infudibulum?
median eminence + pituitary stalk + neural lobe
Remnants of Rathke’s pouch remaining in the roof of pharynx
Pharyngeal hypophysis
Tumor forming from Rathke’s pouch remnants
Craniopharyngioma
- Usually forms in the sella turcica
- Can impinge the optic chiasm
How does formation of the thyroid gland begin?
As a midline invagination of pharyngeal endoderm.
When does the thyroid gland arrive at its definitive location?
Week 7
Inferior to the cricoid cartilage and anterior to the trachea
What do the ultimo pharyngeal bodies become?
They detach from the pharyngeal pouch and migrate toward the thyroid diverticulum
They are invaded by neural crest cells before separation from the pharynx and eventually become Parafollicular cells or C cells in the thyroid gland – they produce calcitonin
What is the most common location for aberrant thyroid tissue?
At the base of the tongue - but can be anywhere along the path of the thyroid
What forms the parathyroid?
Form from pharyngeal pouches 3 and 4
What forms the adrenal cortex?
Proliferating coelomic epithelial cells during week 4-5
What is the primary wave?
During week 5, a subset of proliferating cells separates from the coelomic epithelium and enters the underlying mesenchyme = primary wave of adrenal cortical progenitor cells
Forms the fetal adrenal cortex
What is the second wave?
A second wave of proliferating cells separates from the epithelium and enters the underlying mesenchyme where they surround the cells of the primary wave
Forms the definitive adrenal cortex
What does the definitive adrenal cortex organize into?
Three zone of the adrenal cortex - zona glomerulosa, zone fasiculata, zone reticularis
How does the pineal gland develop and what does it do?
Midline, dorsal diverticulum of the roof of the diencephalon – visible by week 10
Secretes melatonin
