Ltrk is differentially expressed in developing and adult neurons of the Lymnaea central nervous system.

The Trk receptor family plays diverse roles in both development and plasticity of the vertebrate nervous system. Ltrk is a related receptor that is expressed in the CNS of the mollusk Lymnaea, although little is known of its cellular distribution. This study provides three independent lines of evidence (based on RT-PCR, in situ hybridization, and immunohistochemistry) that Ltrk is universally expressed by neurons and dorsal body cells of both the juvenile and the adult Lymnaea CNS. The highest level of expression by neuronal somata occurs in the late juvenile stage, whereas axon collaterals express high levels throughout the animal's life span. Our data support multifunctional roles for Ltrk that parallel those of its mammalian counterparts.

Topographical anatomy of the cerebellum in the guinea pig, Cavia porcellus.

Zebrin II/aldolase C is expressed in a stereotyped array of parasagittal bands and transverse zones in the cerebellum of many animals including birds and mammals. Here, section and whole mount immunohistochemistry has been used to characterize the expression of zebrin II in the cerebellum of the adult guinea pig. Purkinje cells in the adult guinea pig express zebrin II immunoreactivity at three different levels of intensity-high, medium and low. This expression pattern reveals an arrangement of parasagittal bands that are symmetrical about the midline and reproducible between individuals. The expression of zebrin II divides the vermis into four transverse expression domains from rostral to caudal: an anterior zone consisting of one zebrin II-immunoreactive band at the midline and at least three symmetrical bands laterally; a central zone, in which broad zebrin II-positive bands are separated by narrow bands of zebrin II-negative Purkinje cells that disappear caudally to leave no overt compartmentation; a posterior zone consisting of alternating bands of zebrin II-positive and -negative Purkinje cells; and finally, a nodular zone in which nearly all Purkinje cells express zebrin II. In the anterior and posterior hemispheres, zebrin II is also expressed in a banded pattern. These rostrocaudal and mediolateral patterns of zebrin II expression are reminiscent of those in other mammals including rabbit, rat, and mouse, and suggest that there may be a fundamental compartmental organization of the cerebellum that is conserved in mammals.