ABNORMAL-BEHAVIOR OF THE YOLK CENTROSOMES DURING EARLY EMBRYOGENESIS OF DROSOPHILA-MELANOGASTER

After the 10th nuclear cycle the yolk centrosomes follow an irregular pathway. Unlike the somatic centrosomes, which move to the opposite poles of the nuclei to form the bipolar spindles, the yolk centrosomes remain as pairs at one pole of the yolk nuclei or shift feebly and nucleate irregular spindles, most of which have only one main pole. The yolk centrosomes are no longer observed near the yolk nuclei, but progressively move away into the surrounding cytoplasm. Despite the irregular behavior of the centrosomes and although the yolk nuclei cease to divide, the yolk centrosome duplication cycle continues. The early development of Drosophila thus provides an excellent natural system for the study of the uncoupling of the nuclear and centrosomal cycles. © 1991.