Experiments concerning the cleavage stimulus in sand dollar eggs

A cytokinesis furrow is positioned by two consecutive signals

“…The cytokinesis furrow bisects the spindle midway between the microtubule asters, at the site of the microtubule-based midzone, producing two daughter cells. Experiments in some cell types have suggested that the midzone positions the furrow 2,3 , but experiments in other cells have suggested that the asters position the furrow 4,5 . One possibility is that different organisms and cell types use different mechanisms to position the cytokinesis furrow.…”

Contractile Ring-independent Localization of DdINCENP, a Protein Important for Spindle Stability and Cytokinesis

“…The formation of Rappaport or ectopic furrows in sand dollar eggs has been a classical example of the ability of the cytokinesis machinery to assemble between two mitotic asters in the absence of a spindle (Rappaport, 1961). The formation of ectopic furrows in mammalian cells has also been used to determine the requirements for furrow formation (Eckley et al, 1997;Savoian et al, 1999).…”

Quantitative Analysis of Cortical Actin Filaments during Polar Body Formation in Starfish Oocytes

“…In unequal division, a furrow forms on the cortex at different distances from the two centrosomes. On the other hand, Rappaport (1961) clearly demonstrated that the furrow forms in the middle between two centrosomes in an equal division using sea urchin eggs. It is thus of pertinent interest to investigate whether polar body formation is an extraordinary cytokinesis or such normal cytokinesis as is simply explained with the contraction of a contractile ring at the equator.…”