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HETEROTOPIC GRAFTING OF THE SPINAL CORD IN XENOPUS LÆVIS (DAUDIN)
Author(s) -
Hughes A.,
Tschumi P. A.
Publication year - 1959
Publication title -
journal of the royal microscopical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.569
H-Index - 111
eISSN - 1365-2818
pISSN - 0368-3974
DOI - 10.1111/j.1365-2818.1959.tb04464.x
Subject(s) - spinal cord , anatomy , ganglion , biology , neuroblast , commissure , cord , dorsal root ganglion , notochord , lateral funiculus , ventral nerve cord , dorsum , embryo , nervous system , embryogenesis , neuroscience , microbiology and biotechnology , medicine , neurogenesis , surgery
SYNOPSIS Lengths of the spinal cord of young larvæ of Xenopus were grafted into the ventral body wall of host tadpoles of the same age, together with the adjacent somites and notochord. The experimental animals were fixed at various times after the operation, and the grafts were studied in serial sections. The dorsal root ganglia of the grafts underwent little development. Some were suppressed, and there were instances of the fusion of neighbouring ganglia. The greater part of each ganglion was occupied by a mass of undifferentiated neuroblasts, sometimes present in greater numbers than the total of cells in a normal ganglion. In most specimens it was possible to identify the individual ganglia and hence to determine the levels to which the grafted cord belonged. Within the cord the only differentiated neurones were the primary motor cells from which arose ventral roots, dendritic processes, and ventral commissural fibres as in a normal early larva. Dorsal roots enter the cord in a normal fashion, and give off ascending and descending branches. At the caudal pole of the graft the cord regenerated, and some new irregular myotomes were formed. The mantle layer of the cord expanded laterally and underwent a hyperplasia of about twofold in terms of number of cells per spinal segment. The large neuroblastic dorsal horn is prominent, even in instances where there are no dorsal root ganglia. As in previous experiments where the cord is deprived of any influence of the limb buds, there are no differentiated ventral horn cells. The absence of all mature neurones within the mantle layer is a further feature which suggests that the stimuli for their differentiation in normal development proceed not only from the limb but also from the spinal axis. In contrast to the normal cord of late larval stages, no pycnotic nuclei can be seen within the mantle layer of the grafts. It is possible that its cellular hyperplasia is in part due to the absence of histogenetic degeneration.