Morphogenetic movements during the early development of the chick eye. An ultrastructural and spatial study. C. Obliteration of the lens stalk lumen and separation of the lens vesicle from the surface ectoderm.
The obliteration of the lens stalk lumen and the separation of the lens vesic from the surface ectoderm were studied by means of light microscop transmission electron microscopy, scanning electron microscopy and three-dimensional reconstruction. Our observations suggest that the obliteration of the lens stalk lumen is effected by means of cellular protrusions which grown from the apical cell surface, intertwine, meet, form interconnecting junctions and finally fuse. Junctions, and also microfilaments, which probably contract, seem to be temporary structures which assist in drawing the cell projections together and forming a firm tissue complex. Separation of the lens vesicle from the surface ectoderm takes place when the obliteration of the lens stalk lumen is completed. Cell death in a circumscribed area of the lens stalk and absence of the basal lamina of the lens stalk accompany the separation of the vesicle. Necrotic cells are phagocytosed by neighbouring epithelial cells or are expelled into the lens stalk lumen or into the interspace between lens vesicle and surface ectoderm.
D000818:Animals; D002465:Cell Movement; D002470:Cell Survival; D002642:Chick Embryo; D003599:Cytoskeleton / Q000648:ultrastructure; D004475:Ectoderm / Q000648:ultrastructure; D007365:Intercellular Junctions / Q000648:ultrastructure; D007908:Lens, Crystalline / Q000196:embryology* / Q000648:ultrastructure; D009024:Morphogenesis; D009336:Necrosis