Cytokinesis: The effect of initial distance between mitotic apparatus and surface on the rate of subsequent cleavage furrow progress
✍ Scribed by Rappaport, R.
- Publisher
- John Wiley and Sons
- Year
- 1982
- Tongue
- English
- Weight
- 486 KB
- Volume
- 221
- Category
- Article
- ISSN
- 0022-104X
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✦ Synopsis
Abstract
The purpose of this investigation was to determine whether furrows which develop in surfaces distant from the mitotic apparatus function at the same rate as those which develop in surfaces close to the mitotic apparatus. Fertilized, denuded Echinarachnius parma eggs were flattened to a diameter of 175 μm and a thickness of 60 μm 30 to 45 minutes before cleavage in such a way that the mitotic apparatus was eccentric. The initial distance between the mitotic apparatus and the equatorial margin before furrowing was determined as well as the rates of progress of the furrows formed in the opposite margins. The mean rate of progress of furrows which develop in margins 100 to 110 μm from the mitotic apparatus was 5.2 ± 2.8 μm/minute (n = 11). Furrows that developed in margins 65 – 75 μm from the mitotic apparatus progressed at a rate of 10.8 ± 1.8 μm/minute (n = 12). The difference between the means is significant (P < 0.001; t = 6.04; 21 degrees of freedom). The ten fastest furrows progressed at a mean rate of 12.1 ± 0.2 μm/minute and the mean initial distance was 76.3 ± 6.7 μm. The ten slowest furrows progressed at a mean rate of 2.9 ± 0.9 μm/minute and the mean initial distance was 100.5 ± 8.7 μm. The difference between the means of the initial distance measurements is significant (P < 0.001; t = 6.97; 18 degrees of freedom). There was a positive correlation between the difference in initial distances and the difference in rates of progress of two furrows formed in the same cell (r = 0.68; P < 0.005; n = 37) as well as an inverse proportionality between the ratio of the rates of the slower and faster furrows and the ratio of the distances from the mitotic apparatus to the closer and more distant margins (r = 0.63; P < 0.005; n = 37).