Cytoarchitecture of the dorsal thalamus of the rat.

Although several neuroanatomical studies have previously described various subdivisions of the rat thalamus, no comprehensive description of the entire thalamus accompanied by photomicrographs has been available. To provide such a description, the cytoarchitecture of the normal rat thalamus was studied in the coronal plane using a series of celloidin embedded, Nissl-stained 33 micrometers sections spaced 400 micrometers apart. Using the criteria of cell packing density, relative cell size, and the presence or absence of fibers, the thalamus can be subdivided into a ventral nuclear complex which includes the ventrolateral, ventromedial, and ventrobasal nuclei; the intralaminar nuclei which include central medial, central lateral, paracentral and parafascicular nuclei; the midline nuclei which include the medioventral, paratenial, rhomboid, paraventricular, and submedial nuclei; the anterior nuclear group which include the anterodorsal, anteroventral, and anteromedial nuclei; the mediodorsal nucleus; the lateral nuclear complex including both lateral posterior and lateral dorsal; the posterior nuclear complex; the reticular nucleus; and the diencephalic-mesencephalic junction. The terminology used is based on previous studies.