[Ultrastructure of the adrenaline-synthesizing neurons of group A1 in the rat brain normally and under emotional stress].

Ultrastructure of A1 group, participating in the central regulation of cardio-vascular functions was studied in normal conditions and at early stages of an emotional stress. Normal adrenalin-synthesizing neurons of A1 group are characterized by a high intensity of processes of synthesis taking place in them. Abundant terminals, mainly adrenergic ones, which form varied contacts with neurons of A1 group, make a peculair feature. The hematoencephalic barrier in the area of A1 group as a sharply specific organization: transport of substances is mediated not only by pinocytosis, but also through fenestrated formations and through interendothelial spaces. Capillaries of the area studied have a powerful innervation--terminals immediately adjoin the vascular wall, sometimes penetrate into the basal membrane. An immediate contact between neurons and capillaries is noted. In the vicinity of the contact, the laminar complex is usually situated having increased in size vesicles, vacuoles, lysosomas, mitochondria; lobes of the invaginated nucleus are also directed towards this place. At an early stage of the emotional stress, when the arterial pressure is kept at the level close to the normal, rather essential changes are noted in neuronal ultrastructure, with significant spatial rearrangements including. Quantitative alterations of organells and reorganization of the neuronal ultrastructural apparatus results in formation of certain new properties and contribute to transformation of the neural cells to a more effective functional level.