CELIOMESENTERIC AFFERENCE OF THE DORSOLUMBAR NEUROMERS IN HORSE

The frequent variability of the splanchnic branches in all species creates difficulties both in carrying out physiological experiments and, particularly, in interpreting the clinical data; given the need for an in depth study of the comparative physiology, this paper presents some specifications concerning the neuroglandular relations in the mesenteric area in horses. A total of 32 dissections were conducted on fresh, non-mummified corpses and were accompanied by comparative evaluations. The nervous formations were tracked up to the limit of visibility with the magnifying glass of 15 dioptres. To make possible the differentiation of the nervous fibres, the arteries were injected with a red dye. The ganglion formations were investigated with histological methods of differentiation. The dissection also revealed that the efferent fibres which approach the celiomesenteric plexus do not belong, as thought, only to the large and small splanchnic, but also to the lumbar splanchnic nerves which were regarded as being small accessory splanchnic nerves. According to these wrong data, the renosuprarenal plexus would only include abdominal splanchnic afferences and not also lumbar splanchnic afferences, as it actually happens. Speaking of horses, the data reveal the existence of peculiarities regarding the dorsolumbar efferences of the celiomesenteric plexus which detach in most cases from the interganglionar connectives and not directly from the paravertebral ganglia. Another observation is related to the existence of the renal nerves (one or two small fibres), nerves which detach from the abdominal splanchnic nerves which, crossing over the lateral side of the suprarenal gland seem to link it to the kidneys. The existence of postrenal nervous loops might provide evidence, if not on the ontogeny, at least on the way of postembryonic migration of this organ.