Types of neurons in the L1-L2 spinal cord segments as a function of incubation time The number of neurons of each type and at each location in the spinal cord section increases with incubation time. Virus from the prostate (types P, PChAT and DBL) labels the majority of the neurons. Cholinergic prostate neurons (PChAT) are located in the dorsal gray commissure and the intermediolateral area. Their number is approximately constant as a function of time. Cholinergic bladder neurons (BchAT) are found only after three days incubation and these are mainly located in the intermediolateral area. After three days, large numbers of prostate (P) and bladder (B) non-cholinergic neurons (presumably interneurons) are found in the dorsal gray commissure and the intermediolateral area. Double-labeled neurons are confined to the dorsal gray commissure.