[Centrosome morphogenesis in the early development of mice: an immunofluorescence study using antibodies to the centriole antigen]. / Morfogenez tsentrosomy v rannem razvitii myshei: immunofluorestsentnoe issledovanie s pomoshch'iu antitel k antigenu tsentriolei.

The distribution of a centrosomal antigen, recognized by RN-C6 monoclonal antibody (monAB. RN-C6), was studied. The monAB. RN-C6 was directed against the common phosphoepitope in several high molecular cell proteins. In the mouse embryonal fibroblasts the monAB. RN-C6 stained discrete spots in the interphase nuclei, centrioles throughout the cell cycle and the midbody in mitosis. In the oocytes and the early mouse embryos, the monAB. RN-C6 stained only the nuclei, the staining of pronuclei in zygote being absent. In the mouse spermatozoon, the monAB. RN-C6 recognized the centriole and axoneme. Nevertheless, the stained sperm axoneme was revealed in the cytoplasm of early embryos up to the morula stage. No staining was observed in the mitotic spindle or in the midbody, or in any dots in the cytoplasm of oocytes/early embryos. On the blastocyst stage, the monAB. RN-C6 stained first the cytoplasmic dots in some cells, in the spindle poles and midbody. The appearance of stained dots and mitotic figures coincides with that of centrioles revealed at the ultrastructural level in some cells. Thus, during centrosome formation a given centriolar antigen is found only in the centriole, never being accumulated previously in the cytoplasm or in cell organelles.

[An electron microscopic study of centriole and centrosome morphogenesis in the early development of the mouse]. / Elektronno-mikroskopicheskoe issledovanie morfogeneza tsentriolei i tsentrosomy v rannem razvitii myshi.

Using ultrathin section electron microscopy, the precise time of the appearance of centrioles and centrosomes and their morphogenesis in early mouse development was followed. It turns out that in murine morulae and early blastocyst stage centrosomes, centrioles or other microtubule organizing centres are absent; the network of microtubules in interphase cells is diffuse. In 4-day blastocyst four nascent centrioles were found in two cells of trophectoderm in addition to one nascent centriole in the only cell of the inner cell mass. The nascent centrioles were not connected with microtubules. In the late blastocyst (more than 4.5-days of development) among the cells of inner cell mass, cells without centrioles were found, with nascent centrioles but not connected with microtubules; sometimes cells with true centrosomes were seen, having double centrioles and microtubule organizing centres associated with them. Thus, the centrosomes appear asynchronously in different cell types of blastocyst at the preimplantation stage. The centrosome development begins from a self-assembly de novo of the nascent centrioles without any association with microtubules.