HISTOCHEMICAL AND IMMUNOHISTOCHEMICAL LOCALIZATION OF NITRERGIC NEURONAL AND NONNEURONAL CELLS IN THE BURSA OF FABRICIUS OF THE CHICKEN

The bursa of Fabricius of 24 chickens, 2-4 weeks old, was investigated to determine the distribution of nicotinamide adenine dinucleotide hy drogen phosphate-diaphorase (NADPH-d) staining and nitric oxide syntha se (NOS) antigen, by use of NADPH-d histochemistry and NOS immunohisto chemistry, respectively. NADPH-d reaction product was localised in neu ronal cell bodies and nerve fibres. The stained cell bodies were predo minantly in the different bursal compartments; some occurred in the wa ll and between the lymphoid follicles, and some in the immediate vicin ity of blood vessels. Stained nerve fibres travelled mostly with blood vessels, but many were also observed in the connective tissue of the bursa, independent of blood vessels, and some in contact with the lymp hoid follicle and interfollicular epithelium. In addition to neuronal profiles, the interfollicular epithelium of the plicae, and the vascul ar endothelium were densely stained, and lymphocytes were moderately l abelled. NOS immunoreactivity was found in neuron-like cells and fibre s which were confirmed to be neuronal in adjacent sections stained wit h antibodies raised against neuron-specific enolase. It was also detec ted in interfollicular epithelium and lymphocytes but not in vascular endothelium. The distribution patterns of NADPH-d and NOS suggest that nitric oxide (NO) may play a role in the regulation of the secretory activity of interfollicular epithelium and the blood flow through the bursa.