The silver impregnation methods modification for the enteric nervous system study

The lack of adequate methods for histological examination of the enteric nervous system is a significant obstacle to obtaining reliable results on its structural organization at the microscopic level. The use of classical methods of impregnation with silver nitrate, unfortunately, does not provide satisfactory results. The aim of the study was to prove the effectiveness of the universal impregnation method in identifying interneuron cytoplasmic syncytial connections in the human enteric nervous system. We studied supravital preparations of the intestinal wall of mongrel mature age cats (n=7) and biopsy fragments of the small and large intestine (n=30) 20 cm long (small intestine) and 10 cm long (large intestine). After careful preliminary preparation, intestinal fragments were dissected in an aqueous medium under a stereomicroscope. The wall of the fragments was divided into the mucous and muscular membranes, and the submucosa. Each of the intestinal membranes, muscularis propria, mucosa, and submucosa were fixed in 10% methanolfree formalin in a separate vial. Small fragments of the intestinal wall were treated with 0.2% solutions of barium, calcium, and magnesium hydroxides by placing them on glass wool moistened with these solutions. Drops of these solutions were then applied to the surface of the fragments. Silver nitrate was precipitated in a highly alkaline medium (pH=11–13) using 4% hydroquinone as a reducing agent. The formation and precipitation of silver hydroxide occurs due to both the activity of the cation itself and the even more reactive anion. This results in the formation of poorly soluble compounds that precipitate on argyrophilic structures. Metallic silver, reduced from the hydroxide, is deposited in the form of crystals in precise accordance with the location and concentration of the mordant compounds. The adapted universal impregnation method is the result of a nanotechnological principle of an artificially redirected method for correcting the natural restorative properties of cellular constructs. The developed method allows for significantly improved results in the study of histological specimens of the enteric nervous system compared to existing methods.