Light-microscopic studies of locus coeruleus region of the mouse

In an attempt to contribute to the morphology of the locus coeruleus (LC) in the ddY mouse (weighing about 20 g), we made lightmicroscopic investigations using several staining methods in normal conditions. First, we studied the cytoarchitecture and cell numbers of LC by the Kluver-Barrera method and amine demonstrating wet fluorescent method. LC of the mouse measured 600±60 μm in anteroposterior extent in the dorso-lateral tegmental area. At the rostral part of LC small numbers of constituent cells were disseminated, the middle part (principal part) showing triangle-shaped cell accumulation with an apex directed to the IV ventricle. The caudal part, forming a small accumulation of cells, ended directly beneath the IV ventricle. The number of unilateral LC cells amounted to 1250±92 by the Kluver-Barrera method, and 1326±44 by the wet fluorescent method. The LC was cytoarchitectonically divided into dorsal and ventral parts. The cell size of the dorsal part averaged (16.2±2.8) x (25.5±4.6)μm along the longest and shortest axes, while that of the ventral part was (17.3±3.1) x (30.2±5.6) μm.