Structural pattern of the mitoses and hollow formations in the human embryo

Hollow formations in very early stages of the human embryo development have been studied, regarding the behaviour of the mitoses. Semithin sections of the neural tube, of the fissure of the optic cup, and of somites yet furnished with the myocoelic cavity have been observed at the light microscope, after staining with toluidine blue. In all the observed buds a particular and very interesting result has been obtained: all the mitoses are placed in the lining cellular layer looking at the cavity. Dividing cells in the thickness of the wall of the buds are always lacking. In all the cases the dividing cells and the most of the others during the interphase appear to be closely linked to the inner surface of the wall, in the adluminal layer, at level of which cell evaginations form characteristic palings. A hypothesis has been advanced concerning the influence that active substances in the fluid filling the cavities may have in the control of the mitotic processes of the cellular wall.