Organelle distribution in the wedge-, spindle- and inverted wedge-shaped neuroepithelial cells during chick embryo neurulation.

: The formation of the neural tube is a morphogenetic process involving cell-shape changes. The activity of the cytoskeletal elements of the neuroepithelial cells and the interkinetic nuclear migration affect the neuroepithelial cell shape in a way that these cells acquire three distinct conformations of wedge-shaped, spindle-shaped and inverted wedge-shaped cells. Each of them is ultrastructurally characterized in this paper with regard to the intracellular distribution of mitochondria, rough endoplasmic reticulum, yolk droplets, lipid bodies and Golgi apparatus. These distribution patterns are analyzed in relation to the role played by the neuroepithelial cells during the successive phases of neural tube formation.