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Sitting at the back of the Opsin Portal, a lens is shaped like a shallow bowl. This is the:

Inner Lens

The Inner Lens sits in the middle of Lamina. Supporting the Opsin Portal, the Opsin Rings and Ixchel.

Neural Plate in Neurogenesis

Formation of Neural Plate:

The ectoderm receives signals from the notochord (mainly BMP inhibitors like Noggin, Chordin)

These signals induce a region of ectoderm to become neuroectoderm → this thickened area is the neural plate

Neural Plate as a Source of Neural Progenitors:

The cells of the neural plate are neuroepithelial cells, which are multipotent progenitors

Transition to Neural Tube

The neural plate folds into the neural tube

Neuroepithelial cells in the neural tube start differentiating into neurons in a highly organized sequence:

Apical-basal polarity is established

Symmetric divisions expand the progenitor pool

Asymmetric divisions produce one progenitor + one neuron or intermediate progenitor

Contribution to CNS and Neural Crest

Neural crest cells (from neural plate edges) → peripheral nervous system, Schwann cells, sensory neurons

neural plate isn’t just a structure—it’s the launchpad for neurogenesis, determining the fate and organization of future neurons

Neural plate = early neuroepithelium → source of neural stem cells

Induced by BMP inhibitors from notochord

Folds to form neural tube → neurogenesis proper begins

Neural plate edges = neural crest → peripheral neurogenesis

Neural plate border → neural crest cells → migration → PNS components