The postnatal development of the ventral root reflex in the rat; a comparative in vivo and in vitro study

Abstract

The ventral root reflex (VRR) and its postnatal development has been studied in vivo and in an isolated spinal cord preparation from birth up to 14 days. At postnatal days 0, 7 and 14 the VRR typically consists of an early highly synchronized peak (VRR₁) and a later lower amplitude peak (VRR₂). In some cases, especially at day 14 in vivo, there is a longer latency asynchronous wave (VRR₃). As the age of the animal increases the latencies of the first two components VRR₁ and VRR₂ progressively decrease mainly due to the decrease in the central delay occurring over this period. Consideration of the central delays for VRR₁ and VRR₂ recorded in vivo and in vitro indicates that these waves are unlikely to be elicited by C-fibre activation and a long latency C-evoked reflex discharge equivalent to that of the adult could not be reliably recorded. Up to day 7 the appearance of the VRR was similar in both preparations but diverged in the second week of life.