| Abstract |
Several cell lines were established from haploid lethal embryos of the
female-sterile mutant mh 1182 of Drosophila ntelanogaster. An
ultrastructural examination of these cell lines was carried out. In
particular, cells of the 1182-4 line were studied, using diploid Kc cells
as a reference. In Kc cells, a centriole is clearly recognizable in 5.5%
of the 2000 cell profiles examined at random. Centrioles, associated in
diplosomes, appear as very short cylinders of 0.16 muM in length and 0.20
muM in diameter. They consist of the classical 9 microtubule triplets and
are embedded in a cylinder of electron-dense material, 0.35 muM in
diameter. In the 1182-4 cell line, 4000 cell profiles were examined, and
none showed centrioles. In serial sections of the dividing cells, no
centrioles were found either at the spindle poles or elsewhere in the
cytoplasm. We conclude that centrioles are absent in most if not all cells
of the haploid 1182-4 cell line. Centrioles are also missing in a
spontaneously diploidized 1182-4 subline. Their absence is therefore not
directly linked to the haploid state of the cells. The present findings
confirm that centrioles are not obligatory organelles for the organization
of the spindle apparatus in metazoan cells. More importantly, this is the
first report on the existence of a metazoan cell line in which cells
regularly divide without a centriole.
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