Neuropil ( nep ; Waldeyer, 1891 ) : The gray matter (Meckel, 1817) compartment exclusive of cell bodies (Deiters, 1865) and vascular cells, thus consisting of the cytoplasmic extensions of neurons (Waldeyer, 1891) and glia (Virchow, 1846), including synapses (Foster & Sherrington, 1897). It was discovered histologically in spiders by Leydig (1855, p. 413), who called it the Punktsubstanz, or dotted substance in English; Waldeyer first used the term (1891, p. 1354). Also see Bullock & Horridge (1965, pp. 16, 27, 54), Peters et al. (1991, Ch. 11).