Types of neurons in the L6-S1 spinal cord segments as a function of incubation time The number of neurons within each category and location increases with incubation time. The majority of labeled neurons are bladder (B) neurons; there are very few neurons labeled by virus from the prostate (P). Cholinergic neurons (BChAT) are restricted to the intermediolateral area (IML) and their number remains approximately constant. The number of non-cholinergic bladder neurons (B) increases dramatically at longer incubation times. These are presumably interneurons and are found in the intermediolateral area and the dorsal gray commissure (DGC) and, after three days, also in the superficial dorsal horn (SDH).