Developmental and lesion induced cell death in the rat ventrobasal complex.

Naturally occurring and lesion induced neuronal death have been studied in the developing rat thalamus. Natural cell death was present from embryonic day (E)19 until postnatal day (P)8 with a peak occurring at birth. Counts of total neurones indicated a postnatal loss of 27%. Unilateral section of the infraorbital nerve at birth was associated with increased cell death in the contralateral thalamus; this was maximal at P2 and continued until P10. Counts of neurone numbers showed a reduction of about 24% of neurones on the contralateral side. A smaller, more transient decrease was seen ipsilaterally. The lesion induced cell loss was associated with a decrease in volume of the ventrobasal complex, with minimal reduction in cell density.