[Mediator stage in the functioning of the autonomic nervous system in pre- and postnatal ontogeny and the importance of its study for clinical application]

In 1972 a new definition "mediatory stage" in the development of the vegetative nervous system during ontogenesis was introduced and it was stated that at the prenatal stage in the heart, along the course of magistral vessels, and into other organs begin to sprout up at first nervous truncs lacking in mediators, and then, beginning from 8--9 weeks (in man), the mediators appear at first in cholinergic and then in adrenergic plexus (V. N. Shvalev et al., 1972). In clinical embryonal mortality is especially great during the stage of premediatory development, that corresponds to the period of placentation. The beginning of the mediatory stage (the 3d month of prenatal life) is characterized by an intensive differentiation of the neural apparatus in the heart and its innervated structures. At first cholinergic and then adrenergic nerve plexus are formed, nevertheless, by the time of birth these plexus, especially adrenergic ones are not yet fully differentiated. During the first year of life there is noted a rather high rate of so called "sudden death". During the following 3--4 years there is a new intensive rise in differentiation of the cardiac cholinergic and adrenergic nerve plexus and by the 6--8th year of age the density of these plexus reaches its maximum (about 10%). This index is constant up to 40 years of age, and then a noticeable decrease in the density of adrenergic plexus takes place, while that of cholinergic plexus remains rather constant. After 60 years of age an involution takes place at first in adrenergic and then in cholinergic plexus, and the "postmediatory" stage occurs. The problem of "sudden death" is closely connected with the changes described for the mediators in the cardiac and vascular plexuses (V. N. Shvalev, R. A. Stropus and E. K. Morozov, 1978).