ULTRASTRUCTURE OF CENTRAL BODY IN MITOTIC CAGES BLASTOCYST OF THE MICE, DEVELOPING IN SITU
Using ultrathin section electron microscopy the mitotic cells have been investigated in 4,5 day mouse blastocyst. In the poles of mitotic spindle of the several mitotic cells the double centrioles were found. They were surrounded by pericentriolar material. The spindle microtubules grew from pericentriolar material and were associated with mitotic chromosomes. Thus, the true centrosomes, having double centrioles and microtubule organizing centres associated with them, appear in mitotic cells of 4,5 day mouse blastocysts, growing in situ.