Morphological Survey of the Suprachiasmatic Nucleus in Slice Culture Using Roller Tube Method: 1. Architecture of The Suprachiasmatic Nucleus in Vitro

Abstract

The suprachiasmatic nucleus (SCN) obtained from the newborn rat was successfully cultured in vitro for more than 4 weeks by the roller tube method. The slices which were 400 μm i thick and 1 × 1 mm wide at the time of extraction, became thinner and wider week by week, and at the end of 4 weeks, the slices had spread (2 × 2 mm wide) and flattened out to a monolayer or two-cell layers. The culture was composed of three parts: the ependymal zone consisting of piled up ependymal cells in the central part, the neuronal zone consisting of two tightly-packed neuronal cell masses located adjacent to the ependymal zone, and the surrounding glial cell-dispersed zone mainly composed of astrocytes expressing glial fibrillary acidic protein (GFAP). GFAP-immunoreactive astrocyte processes were also found in the neuronal zone, and the distributional density was higher in the peripheral (ventral and lateral) part than the medial part. Cells in the neuronal zone at 4 weeks in vitro increased in size to about twice that at the day of excsion. An electron microscopic study revealed that neurons having little cytoplasm with well developed rough endoplasmic reticulum formed many axodendritic and asymmetrical synapses in the neuronal zone. The present findings suggest that survived SCN neurons extended processes to form a complex intranuclear neuronal network in the neuronal zone in vitro similar to that in vivo. The SCN slice culture system may be useful for analyzing the neuronal network generating circadian rhythms in vitro. © 1994, JAPAN SOCIETY OF HISTOCHEMISTRY AND CYTOCHEMISTRY. All rights reserved.