CELIOMESENTERIC AFFERENCE OF THE DORSOLUMBAR NEUROMERS IN HORSE

Abstract

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.