Cytoplasmic inclusions of neurons in the monkey visual cortex (area 19).

Several unusual neuronal inclusions were found in certain cells of the rhesus monkey visual cortex (Area 19): 1. Filamentous bodies, present in the small stellate cells of layer IV, globoid, 0.3-0.6 mum in diameter, consisting of fine 50 A filaments in a hexagonal meshwork. These are often associated with the labyrinthine bodies. 2. Labyrinthine bodies found exclusively in the small stellate cells of layer IV, including certain neurons with dispersed ribosomes. These are 0.4-0.7 mum in diameter and consist of 900 A wide tubes which interconnect with one another. The walls of these tubes are continuous and made up of a sheet or honeycomb lacework of small hexagonal 150 A subunits. 3. This inclusion, an aggregate 0.3-0.7 mum in size, consists of small membrane-bounded vesicles with a single dense granule associated with other non-membrane bound small dense droplets. The inclusions are always associated with the maturing face of the Golgi complex of certain layer IV pyramidal cells; as such, they may be an unusual product of the Golgi apparatus. These observations were confirmed by examination of stereo pairs of electron micrographs. Speculations are made with regard to possible functions for these inclusions.