J. Comp. Neurol. 409: 592-603 (1999)
During development, spinal cord cells of the frog Xenopus laevis undergo a reduction in size. This phenomenon occurs during neural tube formation and continues at least until the start of metamorphosis. The number and shape of spinal cord cells also changes, but not always in synchrony with the reduction in cell size.
The concomitant change in size and number of spinal cord cells
during embryogenesis suggests that a cleavage type of reductive
division contributes to the decrease in cell size. Blocking
cell division with a combination of hydroxyurea and aphidicolin
(HUA) stops the decrease in cell size during embryonic
development without affecting the differentiation of a specific
class of catecholaminergic neurons. HUA treatment during
larval stages does not block the decrease in catecholaminergic
neuron size. Thus both mitotic and postmitotic
cells decrease in size during spinal cord development. The
two mechanisms are prevalent at different developmental stages
with reductive division and cellular atrophy common during
embryonic and larval phases respectively. Like other
regressive changes such as cell death and synapse elimination,
decreases in cell size affect spinal cord morphogenesis and
presumably the function of developing spinal cord cells.