. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. MORPHOGENESIS IN TACHYPLEUS EMBRYOS 329 TABLE I Frequencies of formation of segment-defective embryos and other monsters by treatment with dithio- threttol and cytochalasin B for 24 hr during active morphogenic movement. Reagents No. of normal embryos No. of segment- defective No. of other monsters No. of developed embryos %of developed embryos per total embryos Dithiothreitol 500 Mg/ml 54 () 142 () 3 () 199 () Cytochalasin B 5 Mg/ml 7 () 26 () 0 () 33 () Normal sea water (fo
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. MORPHOGENESIS IN TACHYPLEUS EMBRYOS 329 TABLE I Frequencies of formation of segment-defective embryos and other monsters by treatment with dithio- threttol and cytochalasin B for 24 hr during active morphogenic movement. Reagents No. of normal embryos No. of segment- defective No. of other monsters No. of developed embryos %of developed embryos per total embryos Dithiothreitol 500 Mg/ml 54 () 142 () 3 () 199 () Cytochalasin B 5 Mg/ml 7 () 26 () 0 () 33 () Normal sea water (for control) 2539 () 1 ( ) 10 () 2550 () 50% of them formed monsters (Fig. 2, Table I). External and histological observa- tions of these monsters revealed that the defect or fusion of appendages occurred with a simultaneous defect or fusion of the corresponding segments. 1001 50 1 o ••. 6 10 11 12 13 14 Developmental stage FIGURE 3. Rates of development and formation of segment-defective embryos after 24 hr treatment with dithiothreitol at different developmental stages. Cross: mean rate of develop- ment in the treated group as a percentage of the rate in controls. Solid circle: mean rate of formation of segment-defective embryos among developed embryos. Vertical lines with limiting marks: ± 1 standard deviation. The embryos were treated at stages shown in the Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Marine Biological Laboratory (Woods Hole, Mass. ); Marine Biological Laboratory (Woods Hole, Mass. ). Annual report 1907/08-1952; Lillie, Frank Rattray, 1870-1947; Moore, Carl Richard, 1892-; Redfield, Alfred Clarence, 1890-1983. Woods Hole, Mass. : Marine Biological Laboratory
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