. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. DIRECT DEVELOPMENT IN MOUiVLA. Figures 8-11. NNI8 antibody staining of Bulletin: villow and Mol- gula retortiformis eggs and AChE expressions of B villosa larvae and M. retortiformis juveniles. The cortical region of/?, villoxa eggs was stained with NN18 antibody (Fig. 8). whereas the cortical region of M. retorti- formis eggs did not stain with NNI8 antibody (Fig. 10). M. follicle cells are autofluorescent. g—germinal vesicle. Fig. 9: Dark-stained AChE positive muscle cells in the tail of a B villwa larva. Fi
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. DIRECT DEVELOPMENT IN MOUiVLA. Figures 8-11. NNI8 antibody staining of Bulletin: villow and Mol- gula retortiformis eggs and AChE expressions of B villosa larvae and M. retortiformis juveniles. The cortical region of/?, villoxa eggs was stained with NN18 antibody (Fig. 8). whereas the cortical region of M. retorti- formis eggs did not stain with NNI8 antibody (Fig. 10). M. follicle cells are autofluorescent. g—germinal vesicle. Fig. 9: Dark-stained AChE positive muscle cells in the tail of a B villwa larva. Fig. 1 1: M retortiformis juvenile exhibiting no AChE activity. Scale bars equal 50 ^/m in (X); 100 jjm in (9): 50/jm in (10). 100 ^m in (I I) of meroblastic types of eggs, such as those produced by birds and reptiles, directly affect patterns of cell division and modify cell movements associated with gastrulation. The presence of a few test cells within the perivitelline space of M. retortiformis eggs was surprising because such cells are thought to be involved in the development of a larval tail fin (Cloney. 1982). Despite the yolky cytoplasm of M. retortiformis eggs, early cell divisions were holo- blastic. and gastrulation was similar to that in indirect- developing embryos containing less yolk. Vegetal pole cells invaginated to form an archenteron. In contrast, gastru- lation in M. pacified embryos is highly modified (Bates and Mallett, 199la) and a typical archenteron never de- velops. Instead, the large, yolky endoderm cells within the central region of the embryo appear to physically impede the inward movements of vegetal pole cells. Ooplasmic segregation movements and early cleavage patterns in M. retortiformis are similar to those in eggs and embryos that have indirect development (Conklin, 1905; Bates and Jeffery, 1988). Unlike the eggs produced by several species of Stye/a and by Boltenia villosa, the eggs of Af. retortiformis do not contain colored pigment granules
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
