[Morphometric analysis of neural tube cells in neurulating chick embryos]

Preliminary report on a morphometric study of the neuroepithelium of 1 S and 7 S -- stage chick embryos. We show first that the nucleo-cytoplasmic ratio and then, that the volume fraction of intercellular spaces, nuclei and cytoplasm as they relate to the neural tube, differ significatively from cephalic to caudal portion of the neural tube. At stage 7 S only the volume fraction of intercellular spaces, nuclei and cytoplasm in the neural tube change along the cephalo-caudal axis of the embryos. Finally, between the two stages, at the back of the head, 1) volume fraction of intercellular spaces in the neural tube remains unchanged 2) nucleo-cytoplasmic ratio increase 3) volumetric density and size of mitochondria do not change, while surface density of endoplasmic reticulum in cytoplasm increases.