Morphological organization of rat hippocampal slice cultures.

Using various histological methods, we investigated the cellular and morphological organization of rat hippocampal slice cultures. Many of the typical features of the hippocampus were retained in vitro over a long period of time. The principal cell types of the hippocampus and dentate gyrus, the pyramidal cells and granule cells, were well preserved and matured in vitro. Nonpyramidal cells and gamma-aminobutyric-acid (GABA) cells were also present in slice cultures and exhibited a strikingly similar dendritic appearance at the light microscopic level. Moreover, GABA-immunoreactive cell bodies and presynaptic terminals could be identified at the electron microscopic level; they expressed typical symmetric synaptic contacts with cell bodies and dendrites. The course of the intrinsic hippocampal fiber pathways--the mossy fibers, Schaffer collaterals, and alveus--was generally retained in vitro. Additional aberrant fiber projections could be identified. Finally, three types of nonneuronal cells could be distinguished on the basis of immunocytochemical methods.