ANALYSIS OF THE REGENERATIVE PROCESS OF THE OPTIC TECTUM IN AN ANURAN (XENOPUS LAEVIS DAUDIN) FOLLOWING REMOVAL OF BOTH OPTIC LOBES

SUMMARY Seventy Xenopus laevis Daudin larvae (55 at stage 50 and 15 at stage 52–53, according to NIEUWKOOP & FABER, 1956) were submitted to bilateral ablation of the optic lobes and a study was made on the gradual evolution of the regenerative process from the 10th-90th day after the operation. The results obtained demonstrated that: 1. Regeneration of the optic tectum takes place by means of neural elements originating in the ependymal layer of the mesencephalic body. These cells, after covering the resection surface, multiply actively and, attaching themselves to the internal surface of the primitive pia mater, they migrate dorsally. The formation of a primary tectal lamina can be observed on about the 10th post-operative day. 2. In the early stages of the regenerative process of the optic tectum two factors have been shown to be of fundamental importance, regeneration of the pia mater and the pressure exerted by the rachidian-encephalic fluid. 3. Up to the 10th post-operative day the primary tectal lam...