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Cell lineages during embryogenesis of the ascidian Halocynthia roretzi were analyzed up until the stage where each blastomere was fated to be only a single tissue type (i.e., the tissue restricted stage) by intracellular injection of horseradish peroxidase using the iontophoretic injection method. Initially, the developmental fates of all blastomeres of the(More)
The tadpole larva of solitary ascidians has 40 notochord cells in its tail. Of these cells, 32 in the anterior and middle part of the tail are derived from the A-line blastomeres, while 8 in the posterior part of the tail originate from the B-line blastomeres. Previous experiments involving continuous dissociation of daughter blastomeres from the first(More)
We have investigated the role of the bone morphogenetic protein (BMP) pathway during neural tissue formation in the ascidian embryo. The orthologue of the BMP antagonist, chordin, was isolated from the ascidian Halocynthia roretzi. While both the expression pattern and the phenotype observed by overexpressing chordin or BMPb (the dpp-subclass BMP) do not(More)
The brain of the ascidian larva comprises two pigment cells, termed the ocellus melanocyte and the otolith melanocyte. Cell lineage analysis has shown that the two bilateral pigment lineage cells (a-line blastomeres) in the animal hemisphere give rise to these melanocytes in a complementary manner. The results of the present investigation suggest that the(More)
Cell lineages during ascidian embryogenesis are invariant. In a previous study, the developmental fate of each blastomere during embryogenesis of the ascidian Halocynthia roretzi was analyzed in detail by intracellular injection of a tracer molecule, horseradish peroxidase (Nishida, H., Dev. Biol. 121, 526-541, 1987). In the present study, the developmental(More)
Cell lineages during development of ascidian embryos were analyzed by injection of horseradish peroxidase as a tracer enzyme into identified cells at the one-, two-, four-, and eight-cell stages of the ascidians, Halocynthia roretzi, Ciona intestinalis, and Ascidia ahodori. Identical results were obtained with eggs of the three different species examined.(More)
Cell lineages during ascidian embryogenesis are invariant. Developmental fates of larval mesodermal cells after metamorphosis are also invariant with regard to cell type of descendants. The present study traced developmental fates of larval endodermal cells after metamorphosis in Halocynthia roretzi by labeling each endodermal precursor blastomere of larval(More)
The tadpole larva of the ascidian Halocynthia roretzi has several hundred mesenchyme cells in its trunk. Mesenchyme cells are exclusively derived from the B8.5 and B7.7 blastomere pairs of the 110-cell embryo. It has been believed that specification of mesenchyme cells is an autonomous process. In the present study, we have demonstrated that(More)
Notochord cells in ascidian embryos are formed by the inducing action of cells of presumptive endoderm, as well as neighboring presumptive notochord, at the 32-cell stage. Studies of the timing of induction using recombinations of isolated blastomeres have suggested that notochord induction must be initiated before the decompaction of blastomeres at the(More)