Tadpole larvae of ascidians have a brain and two kinds cells within the brain. These neural tissues are neural plate and, as in vertebrates, neural induction of the nervous system. The brain and pigment cells are animal (a-line) blastomeres, and inductive interaction line) blastomeres is necessary for formation of neural cells. In order to investigate the characteristics of blastomeres were isolated from embryos of Halocynthia (late blastula) stage, and then their developmental first set of experiments, brain- and pigment-lineage neural induction, failed to develop three specific (epithelial morphology, secretion of larval tunic and specific antigen). These observations suggested a neural induction, indicative perhaps of a permissive embryogenesis. Next, in order to identify which type the inducer of the sensory pigment cells, various sets isolated from 110-cell embryos, in which the fates of restricted to a single type of tissue. The results precursor blastomeres, which are cells of the A-line, a-line cells to form pigment cells. In addition, cord precursors had been ablated, failed to form a brain structure. Therefore, it is probable that the sensory pigment cells are the spinal-cord precursor

This content is only available via PDF.