I wish to express my gratitude to Miss Marilyn Fintak for her technical assistance in preparing material for electron microscopy and to Dr. Norman Klein for his aid in preparing the manuscript. This work was supported by grants GB 2232 and GB 5155 from the National Science Foundation.
Polar granules of Drosophila. II. Ultrastructural changes during early embryogenesis
Version of Record online: 17 MAY 2005
Copyright © 1968 Wiley-Liss, Inc., A Wiley Company
Journal of Experimental Zoology
Volume 167, Issue 2, pages 237–261, February 1968
How to Cite
Mahowald, A. P. (1968), Polar granules of Drosophila. II. Ultrastructural changes during early embryogenesis. J. Exp. Zool., 167: 237–261. doi: 10.1002/jez.1401670211
- Issue online: 17 MAY 2005
- Version of Record online: 17 MAY 2005
Polar granules of Drosophila show distinctive variations in structure at various stages of early embryogenesis and in different species. In most species they are attached to mitochondria at fertilization, then they become free and fragment during the cleavage divisions and during the time of pole cell formation. After pole cells have formed they again coalesce. At the time of migration of the pole cells to the embryonic gonad, the polar granules again fragment and become attached to the outer membrane of the nuclear envelope.
Ribosomes are attached to the periphery of polar granules at the time they are fragmented prior to and during pole cell formation. An hypothesis is presented on the basis of published reports of RNA present in the granules and the ultrastructural observations reported here. This hypothesis suggests that the RNA in polar granules is m-RNA that directs the synthesis of those proteins necessary for the determination of the pole cells to become germ cells.