Cell lineage analysis in ascidian embryos by intracellular injection of a tracer enzyme: III. Up to the tissue restricted stage

摘要: Cell lineages during embryogenesis of the ascidian Halocynthia roretzi were analyzed up until stage where each blastomere was fated to be only a single tissue type (i.e., restricted stage) by intracellular injection horseradish peroxidase using iontophoretic method. Initially, developmental fates all blastomeres 64-cell embryo examined, and thereafter, daughter those that not at traced. The highly invariant except for two candidates “equivalence groups” (J. Kimble, J. Sulston, White (1979). In “Cell Lineage, Stem Cells Determination,” pp. 59–68. Elsevier, Amsterdam/New York), in which cellular interaction is suggested involved specification fates. right left a8.25 cells gave rise otolith ocellus, b8.17 spinal cord endodermal strand complementary manner. No fixed relationship existed between position its derivative. Most restrictions cell occurred early cleavage. numbers generated 44 94 110-cell stage. Eight pairs had yet become Almost complete epidermis, nervous system, muscle, mesenchyme, notochord, tissues described, fate map constructed blastula. For certain tissues, primordial occupied different regions. Supplementary investigations lineage muscle also performed on embryos another species, Ciona intestinalis.