A comparative study of histochemical mapping on the distribution of acid phosphatase and 5-nucleotidase in the forebrain of frog (Rana tigrina).

The four well defined dorsal, lateral, medial and intermediate olfactory tracts of the frog have been studied. During their courses they become intermingled with fibers related to the primordial septum, the primordial hippocampus, the primordial dorsal pallium and the primordial piriform areas. In acid phosphatase preparations all these tracts are completely negative, and, therefore, are not identifiable. However, these tracts have intense staining reaction to 5-nucleotidase throughout their courses. Differences in the distribution of acid phosphatase and 5-nucleotidase are apparent in the hippocampal and anterior commissures. These are negative for acid phosphatase. In 5-nucleotidase preparations the anterior commissure has an intensely positive whereas the hippocampal commissure has a completely negative reaction. The medial septal nucleus is intensely positive for 5-nucleotidase at the anterior hemisphere level. There is a gradual decrease in intensity of staining in this nucleus towards the posterior hemisphere levels so that in the last few sections of the forebrain of the frog the medial septal nucleus is completely unstained or negative. In the acid phosphatase preparations at all levels the medial septal nucleus presents a moderately positive reaction. In 5-nucleotidase preparations, the dorsomedial part of primordial hippocampus is intensely positive whereas the dorsal part of the hippocampus is completely negative. In acid phosphatase preparations, both dorsal and dorsomedial parts of hippocampus are intensely positive. The striatal complex and the lateral septal nucleus are positive for acid phosphatase and negative for 5-nucleotidase. The possible significance of some of these similarities and differences in tracts and nuclei has been considered with reference to the functioning of the various parts. The present histoenzymological preparations have revealed distinct nerve pathways. In some instances clear-cut connections, which had hitherto been unrevealed by neuroanotomical methods, have been demonstrated.