[Interrelationships of the neurosecretory cells and capillaries in the preoptic nucleus of the carp].

Three layers are tentatively recognized in the wall of a blood capillary of nucleus praeopticus (NP) of the carp, Cyprinus carpio L: the inner layer--endothelium, the middle layer--basement membrane with pericytes, and the outer broken layer containing mostly leucocytes and fibroblast-like cells. 1). The plasmalemma of the neurosecretory cells (NSC) makes a direct contact with a capillary: (a) with the plasmalemma of a sole-like process of the endothelial cell (0.1%), (b) with the basement membrane of the capillary (4.9%), (c) with the plasmalemma of the outer layer cells (41.3%). 2) The plasmalemma of the NSC is separated from the capillary by a glial process (53.7%). The first kind of the contact is frequent in the ventral part (3.7%), and the second one--in the dorsal part (29.4%) of NP. The different relations of the NSC--the capillary of the ventral and dorsal parts are due to heterochronism of their development in ontogenesis.