Morphometric features of intramural autonomic nerve ganglia of the intermuscular and submucous plexuses of the small and large intestine of rats in postnatal ontogenesis

BACKGROUND: The morphology of the ganglia of the myenteric (MP) and submucous (SP) plexuses of the gut of adult animals is sufficiently studied, whereas the data on age-related changes in the current literature are incomplete. AIM: To investigate the morphometrical properties of the intramural ganglia of the MP and SP of the rat small and large intestine in postnatal ontogenesis. METHODS: The work was performed on rats of different age groups: newborn, 10-, 20-, 30-, 60-day-old, 24-month-old rats using immunohistochemical method and fluorescent labelled antibodies to protein gene product 9.5 (PGP9.5). RESULTS: During postnatal ontogeny, there was a decrease in the number of ganglia per per 1 mm2 area and an increase in the area of ganglia in the small and large intestine. The mean area of MP ganlia in the small and large intestine increased from birth to 60 days of age, and in the SP - during the first 30 days of life. Mean of the ganglionic density decreased in the MP in the small intestine in the first 60 days, and in the colon at 12 months; this index decreased in the SP in the small and large intestine in the first 60 days of life. The mean number of PGP9.5-immunoreactive (IR) neurons per ganglion in MP did not change in postnatal ontogeny, while in PS it increased in the first 10 days of life. CONCLUSION: In postnatal ontogenesis, the size of the MP and SP ganglia increases and the density of their location per unit of surface of the small and large intestine decreases in the first 30 days of life. The shape of the ganglia and the number of neurons in the MP ganglia do not change in postnatal ontogenesis. The SP ganglia, in contrast to the MP of the small and large intestine of rats, are immature at the time of birth. The formation of the network of the SP ganglia occurs in the first 10 days of life.