The distribution of calretinin-like immunoreactivity has been analyzed in t
he brain of Rana esculenta. Several neurons of nuclei belonging to sensory
pathways, subhabenular area and left habenula were immunopositive. Immunore
activity was present in fibers of motor and sensory pathways, thalamus, teg
mentum and isthmus. The immunolabeling pattern partially overlapped that pr
eviously described in the rat. However, in comparison with the rat, fewer c
ells and fibers were immunoreactive and there were less positive brain nucl
ei, especially in the pallium, septum and striatum, that were totally negat
ive. Taking into consideration that these regions are rather simple in the
frog, the presence of calretinin seems to be consistent with the degree of
complexity of brain areas and segregation of different nuclei. (C) 1999 Els
evier Science B.V. All rights reserved.