The ultrastructural changes of atrial myoendocrine cells (AMC) in various volume loading for heart, the type and the distribution of nerve endings and capillaries in the vicinity of AMC were observed with electron microscopy. The rats deprived or undeprived water received an injection of isotonic saline via the femoral vein (20 ml/mg), then the right auricle was removed and fixed with usual method for EM and partly with TAGO method. The process of atrial specific granules (ASG) secretion, i. e., the limiting membrane of ASG fused with the sarcolemma and opened at this place, and the ASG content was released through this opening into extracellular space, were observed. There were various types of nerve endings nearby AMC. The capillaries were continuous endothelium in type, and show close relation to AMC. The results of this study suggest that AMC secrete ANF by exocytosis mainly, and provide some morphologic data for the physiological and biochemical studies of ANF move and of reaction on each other between the ANF and nerves.

The two-way projection of the intrinsic cardiac neurons in the rat has been studied by means of CB-HRP retrograde tracing and double-labelling with fluorescent tracers. CB-HRP was injected into the right stellate ganglian of the 20 rats. CB-HRP positive neurons were found in the intrinsic cardiac ganglia, moreover, most of the labelled cells localized in the ganglia which were nearby the epicardium of posterior wall of the atria and the root of large vessles. Bb and PI were injected the right stellate ganglia and the wall of the cardiac ventricle of 30 rats respectively, PI-Bb double labelling neurons were found in the posterior wall of the atria for the first time. The present study demonstrated that a few of intrinsi ccardiac neurons give off two long processes, one of which projects to the ventricle, and the other one extends to the stellate ganglion. They may be sensory and may participate the composition of vegetative nervous reflex pathway of heart outside CNS.

Propedium iodide (PI) and bisbenzimide (Bb) were injected into anterior wall of the cardiac ventricle and lesser curvature of the stomach in the rat respectively. We have found that PI labelled cells are distributed in C_4-T_(12), Bb labelled cells in T_4-L_1, PI-Bb double labelled cells in T_6-T_(11) dorsal root ganglia. This result indicate that dichotomizing branches of peripheral process from some of dorsal root ganglionic neuron projecte to two visceral organs simultaneously. By means of immunocytochemistry (PAP method), some of double fluorescence cells are CGRP positive. The significance of the viscero-visceral sensory converging to same primary sensory neuron was discussed.

The intrinsic cardiac ganglion neurons were studied with immunohistochemical PAP technique for localization of calcitonin gene-related peptide (CGRP) in this paper. The result showed that there are many CGRP immunoreactive nerve fibers and a few CGRP immunoreactive neurons within the atrial wall. This fact suggest that CGRP immunoreactive fibere in the heart originate not only from extrinsic cardiac ganglia, but also from intrinsic cardiac ganglia. It is well known that CGRP is closely related to sensory function, and therefore, these CGRP immunoreactive neurons probably be sensory in nature. This result provide some new morphological evidences for identifing the intrinsic cardiac reflex pathway.

The primary sensory neuron simultaneously innervating two or three viscera was studied in this paper, In one group the viscera in neck, thorax, abdomen and pelvis of the rat were paired off, i.e. esophagus-thyroid gland; esophagus-trachea; heartstomach; lung-stomach; left kidney-spleen; urinary bladder-uterus; urinary bladderrectum; uterus-rectum. Propedium iodide (PI) or fast blue (FB) and bisbenzimide (Bb) or nuclear yellow (NY)were injected separately into the first and second organ of paired viscera.PI-Bb (or FB-NY) double labelled cells were observed in corresponding ganglia (dorsal root ganglia and upper and lower ganglia of vagus nerve). In another group, PI, FB and NY were injected into urinary bladder, rectum and uterus separately. We observed a very few of PI-FB-NY triple labelled cells in L_(1-2) dorsal root ganglia.The above findings indicated that there are sensory convergences of visceroviscera in the same sensory ganglion cell in rat.

Ten to twenty ?l of 20-50% horseradish peroxidase (HRP) in normal saline solution was injected into the myocardium of the anterior wall of left and right ventricles in 11 rabbits. The areas containing sino-atria as well as atrio-ventricular nodes and the dorsal wall of the atria were removed separately. Frozen or cryostate sections of these tissues 25-40?m thick, were incubated according to the HRP (tetramethylbenzidine "TMB" method)-AChE combined method. The blue granules produced by the HRP with TMB were observed in the perikarya of a few AChE intensely positive ganglion cells which were located in the epicardium of the dorsal wall of the atria. This indicated the processes of the HRP-AChE double labeled cells distributed to the myocardium of the anterior wall of the ventriculum. It is generally believed that the nerve cells of strong AChE activity can be referred as cholinergic neurons. For this reason, the present study may give further identification to assert the parasympathetic innervation of the ventricular myocardium. The parasympathetic postganglionic neurons innervated the anterior wall of left and right ventriculi are situated primarily in the epicardium of the posterior wall of the atria.