Nerve regeneration in corneal grafts in the rabbit.

A GREAT number of histological studies on corneal grafts are to be found in the current literature. In very few of these, however, has any attention been paid to the nerves. Only a few authors have used nerve stainings. The present investigation has been made with the object of seeing whether any defects in the regeneration of the corneal nerves could have to do with the clouding of the grafts. The processes in regeneration of severed corneal nerves have been studied by Rexed and Rexed (1951). Leoz Ortin (1931) found complete return of sensitivity in his grafts some weeks after operation and he also verified re-innervation at this time histologically. Babel and Campos (1946) described the re-innervation of four cloudy grafts in homine at ages varying from 36 days to 5 years. They found a few disordered nerves in the grafts but were not able to stain any subepithelial nerve network although this was well developed in the host cornea. Franceschetti and Babel (1947) examined a graft from homo which had been clear for 6 years. They found a welldeveloped subepithelial nerve network which connected with the network in the host cornea. They suggested that there might be some connection between the development of the subepithelial nerves and the transparence of the graft. Babel (1950) has collected his experiences in a monograph on anatomical processes in the healing of corneal grafts. He found that it was at least a month before the graft began to be re-innervated. The regenerated nerve fibres were irregularly spread and accompanied by numerous Schwann cells. This he considered to demonstrate a very lively regeneration. He found a similar distribution of the nerves in clear and in cloudy grafts and only seldom saw the nerves accompanying blood vessels. Escapini (1948) studied the degeneration and regeneration of the nerves in corneal grafts in rabbits. He also studied degeneration in vitro. He did not manage to elicit a corneal reflex from any of his