RESUMEN
A study of myenteric and submucosal plexuses was undertaken in the jejunum and ileum of horses and ponies in which no clinical or pathological evidence of intestinal abnormality was apparent. Complete transverse sections of the intestine, stained by a modified haematoxylin and eosin method, were examined using up to 20 sequential sections per animal. Information was gathered from adult, juvenile and fetal equidae. In adults, the longitudinal muscle layers were thinner than the circular muscle layers and the ileum had thicker layers compared to the jejunum. In adults, the submucosal plexus had more neurons per section than the myenteric plexus by mean ratios of 1:3 in the jejunum and 1:1.9 in the ileum. In juveniles, the ratios were respectively 1:1.8 and 1:1.5 and in the fetus 1:2.5 and 1:1.3. The three-dimensional distribution of neurons in both plexuses varied from animal to animal and no consistent pattern was observed. Groups of neurons contained between one and 42 cells per section examined and their length in a cranio-caudal direction varied from 10 to over 100 microns. There were few statistical differences observed between the cranial, middle and caudal portions of either the jejunum or the ileum when neuron groups or neuron numbers per section were examined in 10 adult animals.
Asunto(s)
Caballos/anatomía & histología , Íleon/inervación , Yeyuno/inervación , Neuronas/citología , Envejecimiento/patología , Animales , Caballos/crecimiento & desarrollo , Íleon/citología , Íleon/crecimiento & desarrollo , Mucosa Intestinal/citología , Mucosa Intestinal/inervación , Yeyuno/citología , Yeyuno/crecimiento & desarrollo , Plexo Mientérico/citología , Plexo Mientérico/ultraestructura , Plexo Submucoso/citología , Plexo Submucoso/ultraestructuraRESUMEN
The number of neurons in the coeliacomesenteric ganglia and the myenteric and submucosal plexuses of the jejunum, ileum and small colon, and the pathological changes induced in them, were studied in various types of equine dysautonomia. In all forms of dysautonomia, severe and extensive neuron loss and damage occurred in the ileum. In acute and subacute dysautonomia, jejunal neuron loss and damage were severe, but in chronic cases significantly less loss or damage occurred. The damage followed the same pattern in the small colon but it was always less obvious than in the jejunum. The distribution of the damage was uniform within a segment of the intestine. In fatal cases of dysautonomia, the clinical severity and duration of illness seems, in most instances, to be related to the amount of neuronal disruption occurring in the jejunum. Severe disruption results in acute/subacute dysautonomia, while milder damage leads to the chronic form. No case of dysautonomia was encountered in which enteric neuron loss and damage occurred without significant neuronal disruption also occurring in the coeliacomesenteric ganglia. Heal neuronal damage and loss are not invariably worse than that in the jejunum, and the possible reasons for this, together with the relationship between neuronal damage and possible causes of dysautonomia, are discussed.
Asunto(s)
Enfermedades del Sistema Nervioso Autónomo/veterinaria , Colon/inervación , Enfermedades de los Caballos/patología , Enfermedades de los Caballos/fisiopatología , Intestino Delgado/inervación , Neuronas/patología , Animales , Enfermedades del Sistema Nervioso Autónomo/patología , Enfermedades del Sistema Nervioso Autónomo/fisiopatología , Colon/patología , Caballos , Íleon/inervación , Íleon/patología , Intestino Delgado/patología , Yeyuno/inervación , Yeyuno/patología , Plexo Mientérico/fisiopatología , Plexo Mientérico/ultraestructura , Neuronas/fisiología , Plexo Submucoso/fisiopatología , Plexo Submucoso/ultraestructuraRESUMEN
Histological investigations were undertaken on four sympathetic autonomic ganglia and on the myenteric and sub-mucosal plexuses of the jejunum in healthy animals, in naturally occurring cases of acute, sub-acute and chronic equine dysautonomia and in ponies in which neuronal damage had been induced by the injection of acute grass sickness sera. The degree of neuronal damage is related to the type of dysautonomia. The coeliac-mesenteric ganglion reacts differently from other ganglia and is less severely damaged in cases of short duration. Extensive experimentally induced damage to the coeliac-mesenteric ganglion, even when jejunal damage is also present, is not associated with clinical illness. It is proposed that the rate of autonomic neurone loss and the extent of the damage may both influence the clinical manifestations of grass sickness.
Asunto(s)
Enfermedades del Sistema Nervioso Autónomo/veterinaria , Ganglios Simpáticos/patología , Enfermedades de los Caballos/patología , Yeyuno/patología , Degeneración Nerviosa , Neuronas/patología , Enfermedad Aguda , Animales , Enfermedades del Sistema Nervioso Autónomo/patología , Enfermedad Crónica , CaballosRESUMEN
Damage to the neurons of selected autonomic ganglia was quantified in relation to the severity of the clinical signs shown in acute, subacute and chronic cases of dysautonomia (grass sickness). No connection between the clinical severity of acute or subacute dysautonomia and the amount of neuronal damage in the superior cervical, stellate and coeliaco-mesenteric ganglia could be demonstrated. However, a higher proportion of normal neurons were found in chronic cases. Jejunal submucosal neuronal damage was correlated with clinical severity but further work is required to confirm this finding and to establish how widespread the alimentary neuronal lesions are in dysautonomia of different severities.