Endocrine Devo Flashcards
Both endocrine and exocrine glands are derived from _________. Formation begins as a solid invagination of epithelial cells into the adjacent______
embryonic epithelium
mesenchyme
The initial invagination and its subsequent development is mediated by reciprocal signaling between the
epithelium and the underlying mesenchyme
If an_____ gland is to form, the epithelial diverticulum maintains its connection with the epithelium of origin and begins to form a duct system and secretory components. I
exocrine
if the epithelial diverticulum forms an______ gland, it loses its connection with the epithelium of origin.
endocrine
In both exocrine and endocrine gland formation, the surrounding_____ will form the connective tissue components of the capsule and any subdivisions of the gland.
mesenchyme
The Pituitary Gland or Hypophysis is derived from two ectoderm primordia, one from the oral ectoderm, called the ___________and the other from the ________
Hypophyseal Diverticulum(HD) or Rathke’s Pouch
neural ectoderm, the Infundibulum.
Recent studies suggest that the HD begins as an ectoderm placode located in the midline of a crescent-shaped area of ectoderm adjacent to the cranial end of the neural plate. Moreover, it is believed that the portion of the neural tube adjacent to this placode will become the
infundibulum.
As a result of embryo folding in the_____ plane, the placode comes to lie in part of the surface ectoderm that will form the roof of the oral cavity, and is located in the midline just ventral to the oropharyngeal membrane.
sagittal
During week three, the placode epithelium evaginates cranially into the surrounding mesenchyme forming the
HD or Rathke’s pouch.
Origin of Definitive PItuitary Gland component
The Anterior Wall:
Distal Lobe or Pars Distalis
Origin of Definitive PItuitary Gland component
The Superior Extension at week 11 =
Tuberal Lobe or pars tuberalis
Origin of Definitive PItuitary Gland component
The posterior wall =
Intermediate lobe or Pars intermedia
Origin of Definitive PItuitary Gland component
Infundibulum =
MEdian eminance + pituitary stalk + neural lobe = Posterior pituitiary
is an inferior, midline diverticulum or thickening in the floor of the Diencephalon during week 3. This grows inferiorly to form the neurohypophysis that consists of the Stalk and the Posterior Lobe (pars nervosa) of the pituitary
The Infundibulum (infundibular process)
By week 12, neurovascular links between hypothalamus and pituitary are established, HOW?
Axons of hypothalamic neurosecretory cells and glial cells grow into the stalk. The lumen is obliterated except for an infundibular recess of the third ventricle in the floor of the diencephalon.
Remnants of Rathke’s pouch remaining in the roof of pharynx are called a
Pharyngeal Hypophysis.
forms in the sella turcica, but can also form along the stalk or in the pharynx. Expansion of the tumor superiorly can impinge on the optic chiasm causing vision problems. The tumor can also cause hydrocephalus as well as pituitary dysfunction by compressing the gland.
tumor forming from Rathke’s pouch remnants is called a **Craniopharyngioma. **
How does they thyroid gland start out?
The Thyroid Gland begins as a midline invagination of pharyngeal endoderm, theThyroid Diverticulum between 3rd and 4th pharyngeal arches…It extends inferiorly from the floor of the pharynx between the median tongue bud and copula.
When is the thyroid first visible and what is it’s remanant in an adult?
First visible during week four, the site of this diverticulum will be represented by the foramen cecum in the adult tongue.
The thyroid primordium becomes bilobed as its distal tip expands. It remains connected to the pharynx by a _____until around week 11. A portion of the duct may persist in the mature thyroid as the pyramidal lobe.
Thyroglossal Duct
With time, the thyroid diverticulum is displaced_____ lying anterior to the pharynx, hyoid, and forming larynx.
inferiorly
During week seven, the thyroid arrives at its definitive location
, inferior to the cricoid cartilage and anterior to the trachea (cartilages 2&3).
The_______ bodies detach from pharyngeal pouch four and migrate or are displaced toward the thyroid diverticulum.
Ultimopharyngeal
Neural Crest cells invade the ultimopharyngeal bodies prior to separation from the pharynx and will eventually disperse within the thyroid gland as the
Parafollicular Cellsor C Cells.