. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. OOGENESIS IN DROSOPHILA VUULIS. FIGURE 9. A diagrammatic representation of the proposed synthesis of new plasma mem- brane during the cleavage and subsequent growth of cystocytes. The contractile ring is represented by a thick solid line, old membrane by a thin solid line, and newly synthesized membrane by a stippled line. See text for further discussion. Koch and King (1969) have shown in DrosopJiila melanogaster that, while the cnnal rims undergo morphogenetic changes, the average distance between ring canals remains relat
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. OOGENESIS IN DROSOPHILA VUULIS. FIGURE 9. A diagrammatic representation of the proposed synthesis of new plasma mem- brane during the cleavage and subsequent growth of cystocytes. The contractile ring is represented by a thick solid line, old membrane by a thin solid line, and newly synthesized membrane by a stippled line. See text for further discussion. Koch and King (1969) have shown in DrosopJiila melanogaster that, while the cnnal rims undergo morphogenetic changes, the average distance between ring canals remains relatively the same as the cystocytes grow. Therefore the plasma- lemmal regions that hind microfibrils are not disturbed as the surfaces of the cystocytes expand. The above observations suggest that once cytokinesis is com- pk-te rind fourth generation cystocytes start to grow, new plasma membrane is added t<» regions relatively distant from the canal rims (see Fig. 9D). In the Drosophila male all cystocytes develop in an identical fashion, once divisions cease. In the female, however, the nurse cells and the oocyte follow different developmental pathways, although they are interconnected (see King, 1970 for details). Studies on the female sterile mutation provide clues to the mechanisms terminating cystocyte mitosis and initiating differentiation. Females homozygous for fcs are sterile and produce "tumorous" ovarian chambers (King, Burnett and Staley, 1957, King, Koch and Cassens, 1961, Koch and King, 1964, King, 1969a). The mechanism which stops fourth generation cystocytes from further division in wild type I.), melanogaster does not operate in the majority of fcs chambers. In the mutant Johnson and King (1972) have shown that the normal arrested cleavage of cystocytes is disturbed so that divisions are often com- plete. They conclude that the product of the jes+ gene is required for the forma- tion of a stable canal system, and they suggest that the product of the
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
