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Description
Flashcards by Ashutosh Kumar, updated more than 1 year ago
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Created by Ashutosh Kumar
about 8 years ago
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| Question | Answer |
| List the glands derived from Ectoderm: Mesoderm: Endoderm: | Ectoderm: Adrenal medulla, Anterior and Posterior pituitary gland and parafollicular C cells. Mesoderm: Adrenal cortex and gonads. Endoderm: Thyroid and parathyroid gland. |
| Describe the embryological development of the pituitary gland: | The anterior pituitary gland arises as an upward growth from the oral ectoderm called Rathke's pouch. The posterior pituitary gland arises as a downgrowth of neural crest cells from the neural ectoderm forming the floor of the 3rd ventricle. When Rathke's pouch meets the developing posterior pituitary gland, it differentiates. The posterior/dorsal aspect forms the intermediate lobe and the anterior/ventral aspect proliferates extensively to form the anterior lobe. The lumen of Rathke's pouch narrows, forming a cleft between the anterior and posterior lobe. The epithelial tissue of Rathke's pouch wraps around the infundibulum to form the pars tuberalis. |
| Describe the embryological development of the thyroid gland: | The thyroid gland arises as a down growth of the endodermal floor of the pharynx, migrating caudally to the upper anterior trachea. |
| Describe the embryological development of the parafollicular C cells: | The parafollicular C cells arise from the neural crest cells, which invade the ventral aspect of the 4th pharyngeal pouch, which then enters the thyroid gland via the ultimobranchial body. |
| Describe the embryological development of the parathyroid gland: | The parathyroid gland arises from the endoderm, from the distal end of pharyngeal pouches 3 and 4, which bud off to attach to the posterior of the developing thyroid gland. |
| Describe the embryological development of the adrenal gland: | The adrenal cortex is of mesothelial origin, developing from the cranial end of the mesonephros. They are very large in the fetus and important for development. The adrenal medulla arises as a result of neural crest cells, which when forming the sympathetic ganglia, invade the developing adrenal gland. They are postganglionic neurons which do not develop axons. They are innervated by spinal cord levels T5-T9. |
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