DEVELOPMENTALLY-REGULATED MARKERS IN THE POSTNATAL CERVICAL SPINAL-CORD OF THE OPOSSUM MONODELPHIS-DOMESTICA

The aim of this study was to identify developmentally regulated immuno cytochemical markers to assess development in the cervical spinal cord of Monodelphis domestica. We demonstrate that two commercially availa ble antibodies exhibit altered patterns of distribution during early p ostnatal development Although neurofilament staining was present at bi rth, only the phosphorylated form, recognised by monoclonal antibodies 2F11 or SMI31 could be detected. Non-phosphorylated neurofilament, re cognised by monoclonal antibody SMI32, only became detectable around p ostnatal day 4 (P4) but was restricted to cells in the ventral horn un til 5 weeks postnatum. By 7.5 weeks, SMI32 immunoreactivity (LR) was f ound throughout the grey matter in a pattern similar to that in the ad ult for both SMI32 and microtubule-associated protein 2 (MAP2). The in termediate filament proteins, glial fibrillary acidic protein (GFAP) a nd vimentin (VIM), were detectable at birth in radially oriented, fibr ous cells, but GFAP-IR was restricted to the ventral half of the cord. This ventral to dorsal gradient of GFAP-IR diminished during the firs t week of postnatal life, disappearing by Ps. Many astrocyte-like, GFA P-positive cells were clearly present by 38 days and, in the adult, we re abundant in the white matter. A few VIM-IR cells remained in the ad ult cord, also within the white matter. We suggest that SMI32 and GFAP are useful, developmentally regulated markers for studies of opossum spinal cord development. We are currently using these markers to inves tigate the pronounced rostral to caudal gradient in the postnatal Spin al cord and to assess development in the cultured spinal cord. (C) 199 7 Elsevier Science B.V.