Lugaro Cells

Abstract

Fox (1959) described Lugaro cells as spindle-shaped cells transversely oriented in the granular layer and located immediately beneath the Purkinje cell layer. He observed their horizontally directed dendrites in connection with the basket cell descending axonal collaterals, forming the pinceaux around the axon hillock region of the Purkinje cell. Fox also traced descending dendrites in synaptic relationship with mossy fiber rosettes, at the level of mossy glomerulus, and with the Golgi cell axonal ramifications. According to Fox, the axonal collaterals of Lugaro cells contact the basket cell bodies in the lower molecular layer. Palay and Chan-Palay (1974) reported two types of horizontal fusiform cells possessing different axonal pattern and distribution. One type gives rise to an axon directed downward to the granular layer and reaching the white matter as described by Ramón y Cajal (1955). Sahin and Hockfield (1990) used double label immunocytochemistry to identify and classify the Lugaro cells in cat cerebellum. Laine and Axelrad (1996, 1998) described Lugaro cells with axons projecting to the molecular and granular layers and targeting stellate and basket cells. Melik-Musyan and Fanardzhyan (1998) demonstrated two Lugaro cell types with fusiform and triangular cell bodies. According to these authors, Lugaro cells also exhibit projection fibers traveling from the molecular layer to the white substance. Using electronmicroscopic gold-toning procedure and post-embedding anti-GABA immunocytochemistry, they demonstrated that Lugaro cell axon forms multiple symmetrical synaptic connections with basket and stellate cell soma and proximal dendrites. In addition, partially myelinated Lugaro cell axons form a parasagittal plexus and extend long transverse branches that run longwise to the parallel fibers.