Ganglionic and non-ganglionic neurons in frog heart: do they differ?

This study was designed to compare the morphology of neurons in relation to their distance from the major nerve trunks in the heart of the frog Rana temporaria. Seventy-nine intracardiac neurons were labelled intracellularly with fluorescent markers Lucifer Yellow CH and Alexa Fluor 568. The neurons located on the extensions of the vagus nerve were considered as ganglionic, while neurons spread loosely at further distance from these extensions were considered as non-ganglionic. The mean area of the soma in ganglionic neurons was about 25% larger than in non-ganglionic neurons. Ganglionic neurons had a higher soma area/nucleus area ratio than non-ganglionic neurons. Although both the total number and the total length of dendrite-like processes was similar between the two groups, ganglionic neurons had significantly fewer dendrite-like processes from the soma (1.5±0.3 vs. 3.9±1.0; P<0.05) and shorter total length of these processes from the soma (63±18 μm vs. 178±51 μm; P<0.05). In conclusion, ganglionic and non-ganglionic frog intracardiac neurons exhibit substantial morphological differences. We hypothesize that these differences may indicate different projections or variations in the number of their preganglionic inputs

Complexity of the frog intracardiac neurons. Intracellular injection study

The goal of this study was to determine the structure of intracardiac neurons in the frog Rana temporaria. Fifty-six intracardiac neurons from 8 animals were labelled ionophoretically by the intracellular markers AlexaFluor 586 and Lucifer Yellow CH. Among the labelled neurons, we found the cells of unipolar, bipolar, multipolar and pseudounipolar types. Multiple neuronal processes originated from the soma, the axon hillock and the initial segment of axon. With respect to the soma, the neuron contained (Mean ± SE) 3.5 ± 0.3 long and 5.5 ± 0.6 short processes. Most neurons had the spine, the bubble or the flake like extensions on their soma surface and were classified as Golgi I typeneurons. Few Golgi II type neurons, the presumptive interneurons, were also found. Our findings contradict to a general view that the frog intracardiac ganglia contain only the adendritic neurons of the unipolar type. Our findings demonstrate that the frog intracardiac neurons are structurally complex and diverse. This diversity may account for the complicated integrative functions of the frog intrinsic cardiac ganglia

Gender differences in the human cervicothoracic ganglia

Researchers still further have a morphological interest in sympathetic ganglia. Functionally, paravertebral ganglia are involved in many physiological and pathological aspects of neuropathic, vascular, visceral pain syndromes, the Raynaud’s syndrome and hyperhydrosis. Several interventions on ganglia as surgical and chemical sympathectomy, the ganglion block, and the chemical or thermal sympatholysis are applied for treatment of the pathological conditions. Accurate knowledge about the structure and the location of ganglia is required for a successful aftereffect of these procedures. In scientific literature there are many facts about the structural variations of the sympathetic ganglia related to development, age, pathology, lateral asymmetry and gender. The last one is the indeterminate factor, and the data about it are few and controversial. Still we were missing the information about the gender role on morphometry of human sympathetic ganglia and particularly of the cervicothoracic ganglion. The goal of our present study was to evaluate gender differences in the human ganglia. In our study we found that male cervicothoracic ganglia were longer than female ganglia, 21.33±4.74 mm vs. 14.87±1.84 mm, wider 9.51±1.48 mm vs. 8.76±1.14 mm, and thicker than female ganglia 5.19±0.77 vs. 4.29±0.36 mm. The dissected ganglia exhibited the three main distinguishable shapes: spindle, dumbbell and inverted “L”. We defined gender differences: the female ganglia were mainly of spindle shape (78%), whereas the male ones equally expressed all the three types of the shape (35%, 30%, and 35%). In summary, we determined the gender differences in human cervicothoracic ganglia. We note that these differences are important for interventions on ganglia

Quantitative study of synaptic boutons on frog intracardiac neurons

The frog is a useful model to study the structure and function of intracardiac neurons. The goal of this study was to evaluate the size and distribution of synaptic boutons on the intracardiac neurons in the frog Rana temporaria. Interatrial septa from four animals were double-labelled immunohistochemically for the cholinergic marker choline acetyltransferase (ChAT) and the marker of synaptic vesicles synaptophysin (SYP). One hundred intracardiac neurons were analysed by confocal microscopy. Terminals of preganglionic axons were strongly positive for ChAT, while synaptic boutons were strongly positive for both ChAT and SYP. The number of synaptic boutons per neuron ranged from 2 to 121 and was 10±2 (mean±SE). The total area of synaptic boutons ranged from 6 μm2 to 270 μm2 and was 98±6 μm2. The largest total area of synaptic boutons was found on the axonal half of neuronal soma (59±4 μm2). The total areas of synaptic boutons on both the non-axonal half of soma and the proximal axon were smaller (36±3 μm2; 6±2 μm2; P<0.001). Synaptic boutons occupied 13±1% of the area of the neuronal soma profile. Conclusions: 1) The axonal half of the soma of the frog intracardiac neuron is more densely innervated than the non-axonal half of the soma. 2) The axosomatic and axoaxonic synapses are present on frog intracardiac neurons. The study provides a framework for further experimental studies on the formation and rearrangement of synapses on frog intracardiac neurons