Embryology — Flashcards

Flashcard 351: In which week of embryogenesis do the upper/lower limb buds form? _____

Answer: Week 4 (4 weeks = 4 limbs)

Flashcard 352: _____ is the absence of the skull and brain, resulting in an open calvarium with an absent forebrain

Answer: Anencephaly

Flashcard 353: Which branchial arch gives rise to all intrinsic muscles of the larynx, except the cricothyroid? _____

Answer: 6th arch

Flashcard 354: In which period of lung development do pneumocytes develop? _____

Answer: Canalicular period (weeks 16–25)

Flashcard 355: The neural tube begins as _____ (number) primary vesicles

Answer: three

Flashcard 356: _____ chromosomes are characterized by very short p arms

Answer: Acrocentric

Flashcard 357: Congenital _____ is a failure of umbilical ring to close after physiologic herniation of the intestines

Answer: umbilical hernia

Flashcard 358: The most superior of the 3 primary vesicles (developing brain) is the _____

Answer: forebrain (prosencephalon)

Flashcard 359: What is the embryonic origin of parafollicular cells (C cells) of the thyroid?

Answer: Neural crest cells

Extra: Parafollicular cells (C cells) are derived from **neural crest cells** (migrating into the ultimopharyngeal body, which is derived from the 4th pharyngeal pouch). In contrast, the **follicular cells** of the thyroid gland are derived from **endoderm** (the thyroid diverticulum from the floor of the pharynx).

Flashcard 360: Breast tissue can develop anywhere along the _____, which runs from the axilla to the vulva (e.g. supernumerary nipples)

Answer: milk line