Somite formation and derivatives — Flashcards

Flashcard 1: What embryological disorder results in failure to form the Preoptic Nucleus?_____

Answer: Kallmann Syndrome

Flashcard 2: The embryonic _____ gives rise to the ureter, pelvises, calyces, and collecting ducts

Answer: ureteric bud

Flashcard 3: Which gene of embryogenesis is produced at the base of limbs at the zone of polarizing activity? _____

Answer: Sonic hedgehog gene

Flashcard 4: Which gene of embryogenesis is involved in segmental organization of the embryo in a craniocaudal direction? _____

Answer: Homeobox (Hox) genes

Flashcard 5: What is the embryonic origin of dura mater? _____

Answer: Mesoderm

Flashcard 6: Which gene(s) are produced at the **apical ectodermal ridge** (AER) to regulate the **proximo-distal** axis of limb development?

Answer: FGF (Fibroblast Growth Factor) genes

Extra: Major signaling centers in limb development: - **AER** (Apical Ectodermal Ridge): Secretes **FGF** (stimulates proximo-distal outgrowth). - **Dorsal ectoderm**: Produces **Wnt-7a** (regulates dorsal-ventral axis). - **ZPA** (Zone of Polarizing Activity): Produces **Shh** (regulates antero-posterior axis). - **Hox genes**: Regulate segmental organization (location) of limbs.

Flashcard 7: Spina bifida is due to failure of the _____ vertebral arch to close

Answer: posterior

Flashcard 8: mastoid air cells

Answer: 1st pouch

Flashcard 9: Endoderm lined structures of the ear (1st pharyngeal pouch)

Answer: 1st pouch

Flashcard 10: Embryological origin of the thymus

Answer: 3rd pharyngeal pouch (ventral wing)

Extra: The 3rd pharyngeal pouch gives rise to the Thymus (ventral wing) and the Inferior Parathyroid glands (dorsal wing). Compare with the 4th pharyngeal pouch, which gives rise to the Superior Parathyroid glands.