part of part of central nervous system cell part cluster piriform cortex layer 2 nervous system cell part layer piriform cortex layer 2a layer 2a of piriform cortex UBERON:0022340 Superficial region of layer 2 of the piriform cortex characterized by a less dense packing of cells and a concentration of semilunar cell bodies. piriform cortex layer IIa NLXANAT:091007 layer IIa of piriform cortex