Organogenesis, Neural Tube Formation, and Vertebrate Axis Patterning

All flashcards

What is organogenesis?

Organogenesis is the development of organs and tissues from the embryonic germ layers. It involves cell differentiation, signaling, and coordinated cell movements.

How do signaling and gene expression influence cell differentiation?

Signals guide which genes a cell expresses. The resulting gene-expression pattern helps determine the cell’s specialized identity, such as epidermal or neural.

What is the developmental fate of the neural plate?

The neural plate folds and rolls into the neural tube. The neural tube later forms the brain and spinal cord.

What are somites, and what tissues do they contribute to?

Somites are groups of mesodermal cells arranged beside the neural tube. They contribute to vertebrae, ribs, dorsal skin dermis, and skeletal muscles of the back, body wall, and limbs.

What did the Spemann–Mangold experiment demonstrate?

Transplanted dorsal cells placed in a recipient embryo’s belly region induced a second notochord. The result showed that these cells could organize development of an additional body axis.

Quiz questions

1. If relevant growth-factor signaling is disrupted in the ectoderm, what developmental change can occur?Answer: Ectoderm can differentiate into neural tissue instead of forming the usual epidermal-neural division.
2. What did transplanting dorsal cells into the belly region of a recipient embryo demonstrate?Answer: The transplanted cells could induce a second notochord and organize an additional body axis.
3. Which vertebrate body axis runs from the back toward the belly?Answer: The dorsal–ventral axis.
4. Why is early left–right patterning important in vertebrate development?Answer: It helps position internal organs asymmetrically, such as the heart and liver.
5. What have researchers mapped in the nematode Caenorhabditis elegans?Answer: The developmental fate of individual cells, which varies little between individuals.