Various stages of immature human oocytes were imaged for microtubule, microfilament and chromatin organization. After germinal vesicle breakdown, a small microtubule aster was observed near the condensed chromatin. The asters appeared to elongate and encompass the condensed chromatin. At metaphase I stage, microtubules were detected in the meiotic spindle. The meiotic spindle in metaphase II wa...

Rod-shaped bacteria such as E. coli have mechanisms to position their cell division plane at the precise center of the cell, to ensure that the daughter cells are equal in size. The two main mechanisms are the Min system and nucleoid occlusion (NO), both of which work by inhibiting assembly of FtsZ, the tubulin-like scaffold that forms the cytokinetic Z ring. Whereas NO prevents Z rings from co...

The Abelson family member of non-receptor tyrosine kinase, c-Abl, has an important role in regulation of cellular processes like cell polarity, invasion, proliferation, survival and cell motility. In the present study, we investigated the localization of c-Abl protein during preimplantation mouse embryo development in vitro using immunofluorescence confocal microscopy. We have shown that c-Abl ...

Spindle poles are discernible by light microscopy as the sites where microtubules converge at the ends of both mitotic and meiotic spindles. In most cell types centrosomes are present at spindle poles due to their dominant role in microtubule nucleation. However, in some specialized cell types microtubules converge into spindle poles in the absence of centrosomes. Thus, spindle poles in centros...

Equal segregation of sister chromatids during mitosis requires that pairs of kinetochores establish proper attachment to microtubules emanating from opposite poles of the mitotic spindle. The spindle assembly checkpoint (SAC) protects against errors in segregation by delaying sister separation in response to improper kinetochore-microtubule interactions, and certain checkpoint proteins help to ...

Like many asymmetrically dividing cells, budding yeast segregates mitotic spindle poles nonrandomly between mother and daughter cells. During metaphase, the spindle positioning protein Kar9 accumulates asymmetrically, localizing specifically to astral microtubules emanating from the old spindle pole body (SPB) and driving its segregation to the bud. Here, we show that the SPB component Nud1/cen...

The Drosophila blastoderm and the vertebrate neural tube are archetypal examples of morphogen-patterned tissues that create precise spatial patterns of different cell types. In both tissues, pattern formation is dependent on molecular gradients that emanate from opposite poles. Despite distinct evolutionary origins and differences in time scales, cell biology and molecular players, both tissues...