[Enzyme histochemical study of the brain of Chthonerpeton indistinctum (Gymnophiona, Amphibia)].

In the brain of the Caecilian species Chthonerpeton indistinctum the following enzymes have been demonstrated by means of histochemical techniques: acid phosphatase, alpha-naphthylacetate esterase, acetylcholin esterase. Acid phosphatase occurs in the cytoplasm of the neurons in 4 different types of localization. Its activity in the ventral parts of the brain is markedly higher than in the dorsal ones. Of particularly high activity are: the motor neurons in the tegmentum, the nucleus mesencephali trigemini, individual large neurons in the marginal zone of the grey matter of the telencephalon, which seems to be a special character of the Caecilians among the Amphibia. The ependyma exhibits local differences in respect of acid phosphatase activity. alpha-Naphthylacetate esterase marks in particular the secretory neurons of the hypothalamus, the large perikarya of the nucleus mesencephali trigemini and the motor neurons of the tegmentum. In the telencephalon the alpha-naphthylacetate esterase activity corresponds to that of acid phosphatase. Acetylcholin esterase marks--with certain restrictions--cholinergic neurons. These predominate in Chthonerpeton in the caudal parts of the brain. In the telencephalon amygdala, septal area striatum and the mitral cells are of comparatively high activity. The neurosecretory neurons of the hypothalamus are particularly rich in this enzyme. As an anurans the cholinergic fasciculus retroflexus as asymmetric. The tectum opticum is of secondary simplicity and does not exhibit a clearly recognizable stratification.