Cell turnover in the spinal ganglia ofXenopus laevistadpoles

Abstract

Hughes (1961) has drawn up a balance-sheet of the lumbar ventral horn cells during the development of Xenopus, based both on counts of numbers of ventral horn cells throughout differentiation and of the number of degenerating cells among them at each stage. In this way, he showed that the total number of ventral horn cells is reduced from between 3000 and 4000 at differentiation to 1200 at the end of metamorphosis; that the most rapid period of decline in cell numbers is accompanied by a peak in the time graph of the number of degenerations; and concluded that for every neurone which finally differentiates, some eight or nine neuroblasts undergo degeneration. This is an example of histogenetic degeneration (Glücksmann, 1951), that is, cell death relating to the differentiation of functioning organs. In order to investigate further the relationship of the limb to the developing spinal cord, a similar balance-sheet has been drawn up for the sensory cells of the hind-limbs which are in dorsal ganglia 8–10