Development of vessels in the foetal cortical transplant depending on the place of grafting in the rat brain.

Formation of new blood vessels within the graft is crucial for the survival of brain grafts. Moreover, it must occur rapidly to prevent ischaemic changes in the grafted neurons. A study was made of the development of the vascular system in the foetal cortical grafts depending on the place of grafting in the rat brain. Pieces of neocortical tissue from an 18-day old rat foetus were transplanted into the lateral ventricle, the striatum or the corpus callosum of 2 months old Wistar rats. The vascular system of the graft was visualized from coronal sections of the brain by means of Pickworth's technique 3, 7, 14 and 28 days after transplantation. After 3 days the vessels in the graft were absent. After 7 days the vessel pattern was poor and very simple and after 14 days the vessels formed large number of branches in the graft. After 28 days the pattern of the vascular network in the graft was similar to that of the vessels of the host brain. The size and branching of the vessels showed considerable variations depending on the localization of the graft.