Histology; normal and morbid.
- Dunham, Edward K. (Edward Kellogg), 1860-1922
- Date:
- 1898
Licence: Public Domain Mark
Credit: Histology; normal and morbid. Source: Wellcome Collection.
Provider: This material has been provided by the Augustus C. Long Health Sciences Library at Columbia University and Columbia University Libraries/Information Services, through the Medical Heritage Library. The original may be consulted at the the Augustus C. Long Health Sciences Library at Columbia University and Columbia University.
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![trosoraes reach them they are ealled the polar boches. In these situa- tions they are surrounded by a more distinct zone of hyaloplasm than that whicinenclosed the original parent centrosome, and beyond this the spongioplasm is frequently arranged in radiations of unusu- ally thick Hbres. The polar bodies witii their clear envelopes and the prominent radiations about them are collectively known as the attraction-spheres (Fig. 8). Fig. 8. --b Dividing ceU from ovum of a>-cari.<..,.;,.;. ,„.;„:. K. .-taDctki and Siedlecki.) a, polar body, centrosonie, surrounded by a clear zone; b, chromosomes of the dividing nucleus. Be- tween the polar bodies is the achromatic spindle, and radiating from each attraction- sphere are delicate filaments of spongioplasm. The cytoplasm presents indications of vacuolation. While the polar bodies are separating, or after they have passed into the polar regions of the cell, the nucleus begins to show those changes in structure which constitute karyokinesis. This process mav be divided into a number of phases, as follows: 1. Tlie Formation of the Spirem (Fig. 9).—This consists in a con- densation of the chromoplasm. The branches of the nuclear fila- ments are withdrawn into the substance of the main fibres, into which the nuclear membrane or ])eripheral network bounding the nucleus is also absorbed. The vesicular character of the nucleus is lost during these changes in the arrangement of the chromoplasm, which appears as a loose tangle or skein of one or more threads of uniform diameter lying freely in the body of the cell. This skein is called the spirem. The chromoplasm in this condensed con- dition stains more deeply with nuclear dyes than in the resting con- dition of the nucleus. The nucleoli in the meantime become faint and seem to ultimately disappear. They play no part in the process](https://iiif.wellcomecollection.org/image/b21223841_0031.jp2/full/800%2C/0/default.jpg)
