Term: piriform cell

Definition: The piriform cells have ovoid or cup shaped cell bodies, 10-15 micrometers in diameter, located within a narrow lamina along the deep margin of the zone of horizontal cells. The restriction of the piriform cell somata to the boundary between the zone of horizontal cells and the zone of vertical cells is remarkably accurate and consistent. The piriform cells give rise to 2-5 dendrites from the superficial surface, which course through the zone of horizontal cells to terminate just beneath the surface. As the ascending dendrites approach the surface they branch more frequently, almost always by equipartition, to form a complicated intermingling bouquet of slowly tapering dendrites, 150-350 micrometers in width and slightly less than 200 micrometers in depth. The axon most frequently takes its origin from the base of the soma, but sometimes it arises from one of the low order dendrites. From its origin the axon runs immediately down through the zone of vertical cells, occasionally with collaterals which may arborize within the superficial laminae. The axon is thin and smooth, occasionally with en passant varicosities.