THE ACCESSORY CELL AND YOLK HALO OF THE OÖCYTE OF THE FRESHWATER TURBELLARIAN HYDROLIMAX GRISEA (PLATYHELMINTHES; PLAGIOSTOMIDAE)
Open Access
- 1 December 1974
- journal article
- other
- Published by University of Chicago Press in The Biological Bulletin
- Vol. 147 (3) , 618-629
- https://doi.org/10.2307/1540745
Abstract
1. A single cell, the accessory cell, completely surrounds the growing oöcyte of H. grisea. 2. Cytoplasmic processes from the inner surface of the accessory cell extend into the oöcyte. The cytoplasms of the accessory cell and of the oöcyte do not intermix. 3. Microvilli extend from the outer surface of the accessory cell. 4. It is suggested that the accessory cell is a nurse cell which transports nutrient material to the growing oöcyte. 5. The yolk halo consists of two layers, each of different origin. The inner layer is composed of the numerous microvilli which extend from the accessory cell into membrane-delimited canals within cells of the turbellarian parenchyma. The spherules of the outer portion of the yolk halo are derived from accessory parenchymal cells. The function of the yolk-halo spherules is unknown.Keywords
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