Polar granules and pole cells in the embryo of Calliphora erythrocephala: ultrastructure and [3H]leucine labelling.
The polar granules in Calliphora undergo a gradual fragmentation during early cleavage, but reaggregate after pole-cell formation. Autoradiographic analysis showed that the pole cells in Calliphora acquire a higher [3H]leucine label than the rest of the embryo during the blastoderm stage. Such an increased label was not seen in the pole plasm before pole-cell formation or in the pole cells during gastrulation. Electron microscopic autoradiography revealed that the polar granules are substantially labelled during the blastoderm stage. At the same time, characteristic nuclear blebs appear in the pole cells. The observations are consistent with the hypothesis that polar granules contain maternal messenger RNA, which is released and translated into proteins.
D000818:Animals; D001756:Blastoderm / Q000648:ultrastructure; D002454:Cell Differentiation; D002455:Cell Division; D003594:Cytoplasmic Granules / Q000648:ultrastructure; D004175:Diptera / Q000196:embryology*; D005260:Female; D007930:Leucine / Q000378:metabolism; D008854:Microscopy, Electron; D009685:Nuclear Envelope / Q000648:ultrastructure; D010063:Ovum / Q000648:ultrastructure*; D013997:Time Factors
D007930:Leucine