This electron microscopic study confirms that basal lamina (BL) begins to cap the cut end of the spinal cord 15 days after spinal cord transection. BL is first seen immediately adjacent to reactive glial cells but only when there is collagen in the nearby interstitial space. This finding suggests that collagen may provide a trigger to initiate the production of BL by reactive glia. We found no direct evidence that BL in this injury area impeded the outgrowth of regenerating neurites.