Non‐uniform distribution of cellular phenotypes in the optic tectum of the leopard frog

Abstract

Regional specialization in the retina have been described in a number of species. We have investigated whether such specializations can be found in the optic tectum, an area of the brain responsible for the processing of visual information. Using the tectum of Rana pipiens, we have examined the distribution of three different cell types defined on the basis of their immunoreactivity to somatostatin, substance P, and serotonin antibodies. These three immunoreactive cell populations had differing, nonuniform distributions in the optic tectum. Somatostatin-line immunoreactive cells were largely restricted to the caudal one-third of the tectum, whereas both substance P-like immunoreactive (SP-ir) and serotonin-like immunoreactive (5-HT-ir) cells were found unequally represented throughout the tectum. The percentage of SP-ir cells decreased significantly in both the posterior and medial directions from its high in the anterior lateral tectum. Although serotonin-like immunoreactivity was also greatest in the lateral tectum and decreased significantly medially, it was largely constant in the anterior-to-posterior dimension. The populations of SP-ir and 5-HT-ir cells were nonoverlapping. Our results suggest that information may be processed differently in different regions of the optic tectum.

Distribution and regulation of substance P‐related peptide in the frog visual system

“…In the adult frog, transection of the optic nerve results in a decrease in the percent of SPL-ir cells in the tectal lobe still receiving optic nerve input (Liu and Debski, 1995). Expression in the deafferented lobe appears unchanged.…”

“…An SP-like positive apical dendrite can sometimes be seen extending upward into the more superficial layers. SPL-ir cells are one of a number of different cell types that are non-uniformly distributed within different tectal regions (Debski et al, 1995). In mature tectum, the percentage of these cells is highest in anterior lateral tectum and decreases both posteriorly and medially.…”

Somatostatin in the brain of the cave salamander, Hydromantes genei (Amphibia, Plethodontidae): Immunohistochemical localization and biochemical characterization

“…In contrast, in frog positive perikarya are located in the laminar layers of the tectum and in several tegmental nuclei, including the anteroventral nucleus, the interpeduncular nucleus, and the nucleus profundus mesencephali (Vandesande and Dierickx, 1980;Laquerrière et al, 1989;Debski et al, 1995;Petko and Orosz, 1996). A recent study has shown that in the urodeles Pleurodeles waltl, somatostatin-immunoreactive cell bodies occur in the tegmentum of the mesencephalon and in the interpeduncular nucleus (Gonzá lez et al, 2003).…”

5-HT-like immunoreactivity in the brains of plethodontid and salamandrid salamanders ( Hydromantes italicus , Hydromantes genei , Plethodon jordani , Desmognathus ochrophaeus , Pleurodeles waltl ): an immunohistochemical and biocytin double-labelling study

“…Bar: 100 µm neuronal system exists (Parent 1973(Parent , 1975Yoshida et al 1982;Shimizu et al 1983;Ueda et al 1984;Van Mier et al 1986;Adli et al 1988;Liu and Debski 1995;Debski et al 1995). The distribution of the 5-HT-lir cell and fibre system in frogs closely resembles the pattern found in salamanders, although in a recent study in Rana pipiens, in addition to the known locations of 5-Ht-lir cells, a large number of neurons with 5-HT lir were found in the tectum and in the nucleus isthmi Debski et al 1995). In frogs, cell bodies with 5-HT lir were found in the thoracic spinal cord (Adli et al 1988).…”