Immunoreactivity of the calbindin D28k in the parahippocampal gyrus of chinchilla

Ten adult male chinchillas were used. The localisation of calbindin D28k (CB) was examined with the use of two types of reactions: immunocytochemical peroxidase-antiperoxidase and immunofluorescence staining with a specific monoclonal antibody against CB. Immunocytochemical examination demonstrated the presence of CB-positive neurons in the following layers of all parts the parahippocampal gyrus (PG): marginal, external cellular, middle cellular, and internal cellular, i.e. in entorhinal area, parasubiculum, and presubiculum. Immunofluorescence staining revealed the presence of CB in both Hu C/D- immunoreactive (IR) neurons and nervous fibers of the PG. CB-IR neuronal cell bodies were moderately numerous (ca. 10% of Hu C/D-IR neurons) and clearly distinguished from the background. Each layer of the brain area consisted of two types of neurons: pyramidal and multiform. Among the second type of neurons, four kinds of morphologically different neuronal subclasses were observed: multipolar, bipolar, round, and Cajal-Retzius cells. It is concluded that the expression of CB in the PG of the chinchilla is species specific and limited to several subclasses of neurons.