[Age and features of the content of myelinated fibers in nerves of the splenic plexus of man].

The amount of the myelin fibers (MF) has been calculated in transversal serial sections of the nervous-vascular complexes of the splenic artery in newborns, in persons of mature (the 1st and 2d periods), elderly and old ages. In each age group 20 complexes have been studied. The total amount of the MF in persons of mature age (the 1st period) in 4.2-6 times greater (initial--terminal parts of the plexus) than in newborns, in the persons of old age it is 4-2.1 times less than in persons of mature age (in both cases P less than 0.001). Thin MF predominate, their relative contents in the aggregate of all classes of the MF in newborns are 92%, in mature persons--87%, in old persons--65%. Decreasing part of the thin MF together with increase of their absolute amount in the mature persons, comparing to the newborns, depends on higher rates in differentiation of middle and thick MF. Phenotyping peculiarities and stages of productive development, stabilization (the 1st-2d periods of the mature age), involutions of the nerve connections are defined in the splenic artery. The amount of the MF predominates in the nerves of the initial part of the plexus comparing to its terminal part. There is a direct correlative dependence between the amount of the MF in the plexus nerves and the size of the lumen in the splenic artery. Changes in the amount of the MF of different classes reflects qualitative differences of the splenic innervation relations at certain stages of the human postnatal development.