. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 240 T. DENO ET AL epidermis MUSCLE endoderm mesenchyme muscle NOTOCHORD. epidermis brain palps _sense organ endoderm notochord brain stem spinal cord MUSCLE FIGURE 1. A diagram illustrating the nomenclature of blastomeres of the 8-cell-stage ascidian embryos according to Conklin (1905a), and also listing the derivatives from each blastomere pair. The derivatives shown with small letters are based on previous studies (Conklin. 1905a; Ortolani, 1955) while those with capitals are those obtained in our recent study (Nishida and
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 240 T. DENO ET AL epidermis MUSCLE endoderm mesenchyme muscle NOTOCHORD. epidermis brain palps _sense organ endoderm notochord brain stem spinal cord MUSCLE FIGURE 1. A diagram illustrating the nomenclature of blastomeres of the 8-cell-stage ascidian embryos according to Conklin (1905a), and also listing the derivatives from each blastomere pair. The derivatives shown with small letters are based on previous studies (Conklin. 1905a; Ortolani, 1955) while those with capitals are those obtained in our recent study (Nishida and Satoh, 1983). ment of a putative muscle-specific enzyme, acetylcholinesterase (ACHE), and of myofibrils has been shown in partial ascidian embryos derived from isolated pairs (Whittaker el a/., 1977; Crowther and Whittaker, 1983). Recent analyses of cell lineages in ascidian embryos, however, have demonstrated that muscle cells are derived not only from the pair, as was formerly believed, but also from both the (the anterior vegetal blastomeres) and pairs (the posterior animal blastomeres) (Fig. 1; Nishida and Satoh, 1983; Zaloker and Sardet, 1984). In a previous study, we isolated the pairs from 8-cell Ciona embryos and showed that AChE development as well as myofibril differentiation took place in partial embryos originating not only from isolated pairs, but also from 8-cell embryos lacking progeny cells (Deno el a/., 1984). The goal of the present study was to determine the ability of quarter embryos derived from the isolated , , , and pairs to express AChE activity. MATERIALS AND METHODS Animals, gametes, and embryos Eggs of the ascidians Ciona intestinal is (L.) and Halocynthia roretzi (Drashe) were used in this study. C. intestina/is adults were collected at Takahama, Wakasa Bay, Japan and maintained in temperature-controlled aquaria (18°C) under constant light to induce oocyte maturation. Eggs were rem
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
