The BHK-21 (baby harmster kidney cells) growing on glass are observed by SEM after critical point drying. The cell shape, the main surface structure, and their alteration during the cell cycle are described. As a particular stage, the senile cells are also mentioned.Three other cell lines: HeLa, IB-RS-2 and chicken fibroblast, sampled in same way, are studied for comparison. In all these four cell lines the changes of cell surface morphology follow a common pattern. And notably, the microvilli of all of them have the similar diameters, though their shapes and distributions are distinct from each other.Using cytochalasin B and colchicine as specific inhibitors it is shown that the microvilli and blebs are mainly related to the microfilaments, while the filapodia are to microtubules.

Nuclear reconstitution around Lambda DNA in a cell-free system from Xenopus eggs involves distinct steps at ultrastructural level. First, Lambda DNA polymers were induced to form chromatin-like structures with the proteins in egg extracts. Then, along with membrane vesicles and nuclear pore components attached to them to assemble double nuclear membranes, these chromatin-like structures underwent variations from condensation to decondensation, simultaneously. It is different from the nuclear reconstitution induced by chromatin in that, while membrane vesicles were attaching to the chromatin-like structures to fuse each other, the assembly of nuclear pore complexes occurred practically.