THE DEVELOPMENT OF SYNAPTOPHYSIN-LIKE IMMUNOREACTIVITY IN THE LUMBOSACRAL ENLARGEMENT OF THE SPINAL-CORD OF THE OPOSSUM MONODELPHIS-DOMESTICA

The presence of synaptophysin in the lumbosacral enlargement of develo ping opossums, Monodelphis domestica, was studied immunohistochemicall y at the Light microscopic level. In newborn, synaptophysin-labeling w as observed in the presumptive white matter, presumably in growing axo ns, and was scant in the ventrolateral gray matter. Over the next 3 we eks the labeling filled the gray matter following a general ventrodors al gradient. Labeling was found in the white matter until the fifth we ek. Synaptogenesis in the lumbosacral enlargement of the opossum thus occurs mostly postnatally, when many descending axons have already rea ched that level. It is particularly intense in the ventral horn when t he hindlimbs begin to move, and in the dorsal horn when sensorimotor r eflexes can be elicited. (C) 1998 Elsevier Science B.V.