Endocrine Devo Flashcards
2 most common problems of abnormal thyroid gland embryologic genesis?
- Thyroglossal duct cyst–cyst can grow if the thyroglossal duct does not disappear
- presents as anterior midline mass on neck - Lingual thyroid–thyroid did not migrate down thyroglossal duct
- presents as mass at base of tongue
Pharyngeal hypophysis
Congenital abnormality:
Remnants of Rathke’s pouch that remain in roof of pharynx after birth.
Foramen cecum
This is the midline fold at the base of the tongue. In the embryo, this is where thyroid tissue first develops before traveling via the thyroglossal duct to its mature position.
Lingual thyroid (congenital abnormality) is found here.
Adrenal cortex development:
-describe, from embryo to post-birth
- Fetal Adrenal Cortex
- formed by initial wave of epithelial cells, and is 20 times larger than definitive cortex. Relies on placenta to produce progesterone and androstenedione b/c it lacks 3-beta HSD dehydrogenase.
- involutes starting at birth and completely regresses by months 6-12. - Definitive Adrenal Cortex
- formed by 2nd wave of proliferating epithelial cells, after birth.
Thymus:
-arises from what pharyngeal pouch?
- inferior portion of pharyngeal pouch 3.
- The thymus tissue migrates inferiorly from original location
Neural crest cells:
-What do they form in the endocrine system? (2)
- Adrenal medulla
- Parafollicular C cells in the thyroid (secrete calcitonin)
Adrenal gland cortex vs medulla
-what are the origin embryonic tissues?
- Cortex–mesoderm
- medulla–ectoderm (neural crest cells–chromaffin cells)
Ecto, meso, or endoderm? (may contain more than 1)
- pituitary
- thyroid
- parathyroid
- adrenal
- ectoderm (anterior–oral ectoderm, posterior–neuroectoderm)
- endoderm (parafollicular C cells are neural crest ectoderm)
- endoderm
- mesoderm (cortex), ectoderm neural crest (medulla)
Embryo does not develop 3rd and 4th pharyngeal pouches
- what’s this called
- how are parathyroid and thyroid affected?
DiGeorge syndrome
- parathyroid missing (develops from pouches 3/4)
- thyroid normal b/c not developed from pouches 3/4 (except for parafollicular C cells from pouch 4, which serve no real function secreting calcitonin)
CATCH 22
Cardiac abnormalieis
Abnormal facies
Thymic aplasia (thymus from pouch 3)
Cleft palate
Hypocalcemia (no PTH)
22p11
Origin of thyroid gland components:
- thyroid follicular cells
- parafollicular cells
- parathyroid gland prinicipal cells
- endoderm (thyroid diverticulum)
- neural crest cells from ultimopharyngeal body
- Endoderm (dorsal wing of pharyngeal pouches 3, 4)
Craniopharyngeoma
-formed from what tissue
Formed from oral surface ectoderm of Rathke’s pouch.
aka “Rathke’s pouch tumors”
Pineal gland
- what does it secrete
- how does this hormone affect other hormones?
- Melatonin
- It has inhibitory effect on anterior pituitary secretion of LH, FSH
Parathyroid glands:
-describe embryogenesis (superior vs inferior glands)
- Derived from endoderm and migrate downwards
- Superior: migrates from 4th pharyngeal pouch
- Inferior: migrates from 3rd pharyngeal pouch
Rathke’s pouch:
-abnormal growth can cause what 2 problems?
- Pharyngeal hypophysis–remnants of pouch remain in roof of pharynx
- craniopharyngeoma–tumor of Rathke’s pouch tissue
Rathke’s pouch
- what is it
- aka what
- Diverticulum formed from oral suface ectoderm. This joins with the neuroectoderm and eventually becomes the anterior pituitary.
- aka Hypophyseal Diverticulum