Which event occurs on day 22 of neural development?

Which event occurs on day 22 of neural development?

• A. Bending of the neural plate
• B. Formation of the neural crest
• C. Closure of the neural tube
• D. Proliferation of neural progenitors

Answer: (A)

Neurulation is the process that transforms the flat neural plate into a hollow neural tube, and day 22 marks the moment when the plate begins to bend inward to form the neural groove as the neural folds rise. This bending is the first clear morphological change toward tube formation, signaling the start of neurulation’s turning point from a sheet to a tube. Closure of the neural tube happens a bit later, as the folds fuse along the length and the neuropores near the head and tail close in the following days. The neural crest cells, which arise at the border of the neural plate and non-neural ectoderm, begin their emergence around this period but the defining event you’d spot around day 22 is the bending of the neural plate. Proliferation of neural progenitors is ongoing to expand the neural tissue, but it isn’t a discrete day-specific event like this bending step.

Neurulation is the process that transforms the flat neural plate into a hollow neural tube, and day 22 marks the moment when the plate begins to bend inward to form the neural groove as the neural folds rise. This bending is the first clear morphological change toward tube formation, signaling the start of neurulation’s turning point from a sheet to a tube.

Closure of the neural tube happens a bit later, as the folds fuse along the length and the neuropores near the head and tail close in the following days. The neural crest cells, which arise at the border of the neural plate and non-neural ectoderm, begin their emergence around this period but the defining event you’d spot around day 22 is the bending of the neural plate. Proliferation of neural progenitors is ongoing to expand the neural tissue, but it isn’t a discrete day-specific event like this bending step.