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dc.contributor.authorAli, Hassan Ahmeden
dc.date.accessioned2018-05-14T10:11:29Z
dc.date.available2018-05-14T10:11:29Z
dc.date.issued1979en
dc.identifier.urihttp://hdl.handle.net/1842/29660
dc.description.abstracten
dc.description.abstract1. The aim of the thesis was to contribute new knowledge on the intestinal nerve plexuses of birds using the domestic fowl (Gallus gallus) as the subject.en
dc.description.abstract2. The literature on the histology of the intestinal nerve plexuses was analysed and the gaps in our present knowledge of the structure of the plexuses were outlined.en
dc.description.abstract3. The detailed objectives were: (a) to establish the appearance and distribution of the enteric plexuses using both histochemical and empirical staining methods; (b) to provide quantitative data on the myenteric plexus by estimating the number and size of the perikarya; (c) to provide information on the fine structure of the myenteric and submucosal plexuses; (d) to interpret the findings in the light of the available information on intestinal motility in birds.en
dc.description.abstract4. The appearance and distribution of the nerve plexuses was investigated in male and female, immature and adult birds, by means of the cholinesterase and glyoxylic acid fluorescence histochemical methods and the osmic acid and silver empirical methods. The nervous tissue was examined in strip preparations, whole mount stretch preparations and frozen sections.en
dc.description.abstract(a) Cholinesterase-positive and fluorescent fibres were distributed at all levels of the intestines as myenteric, submucosal, muscle, mucosal and perivascular plexuses. The nerve cell bodies were restricted to the myenteric and submucosal plexuses and were mainly cholinesterase-positive. None of the perikarya was fluorescent. Treatment with reserpine, nialamide and L-DOPA suggested that the fluorescent fibres were probably adrenergic. The density of innervation varied at different levels of the intestinal tract and was best developed in the rectum.en
dc.description.abstract(b) The myenteric plexus remained attached to the longitudinal muscle layer and consisted of a primary meshwork of relatively thick nerve bundles within which was a secondary meshwork of finer nerve bundles. The appearance of the myenteric plexus varied along the intestines, the primary meshwork being best developed in the rectum. The perikarya occurred mainly in well-defined ganglia at the nodes of the plexus, a small number of cells occurring in the internodal nerve bundles and the nodes of the secondary meshwork. The majority of the fluorescent fibres in the nodes were strongly fluorescent and varicose, whereas in the internodal bundles most of the fibres were weakly fluorescent and non-varicose. Pretreatment with NADH-Nitro BT to stain the nerve cell bodies showed that the strongly fluorescent varicose fibres formed dense pericellular networks around the majority of the ganglion cells.en
dc.description.abstract(c) The position of the submucosal plexus varied in the different regions of the intestines. In the small intestine the plexus lay close to the inner surface of the circular muscle layer, whereas in the rectum and caeca the plexus was situated deeply within the submucosa. The appearance of the submucosal plexus also varied in the different parts of the intestines. Thus, in the small intestine and rectum the plexus was arranged in one plane, whilst in the caecum it consisted of outer and inner parts. The nerve cell bodies occurred in both the ganglia and internodal bundles, but in the small intestine the perikarya were almost equally distributed between the nodal and internodal regions. Many fluorescent varicose fibres surrounded the non-fluorescent ganglion cells. The number of the internodal varicosities in the submucosal plexus appeared to be far less than in the myenteric plexus.en
dc.description.abstract(d) The circular muscle layer, especially in the rectum, contained a substantial number of cholinesterase-positive and fluorescent fibres. The longitudinal layer of muscle was sparsely innervated except in the rectum. The fluorescent fibres in the longitudinal muscle layer of the small intestine and caeca were associated with blood vessels.en
dc.description.abstract(e) The mucous membrane was innervated by fine cholinesterasepositive and fluorescent nerve bundles from the submucosal plexus. These nerve fibres formed dense meshworks beneath the intestinal glands and within the villi. None of the fibres entered the epithelium. The muscularis mucosae was sparsely innervated.en
dc.description.abstract(f) The intestinal arteries were accompanied by thick anastomosing bundles of cholinesterase-positive fibres. A few nerve cell bodies occurred along the course of the periarterial nerves. Thick bundles of non-varicose fluorescent fibres also ran close to the arteries and gave off fine strongly fluorescent varicose fibres which entered the arterial wall. The intestinal veins were sparsely innervated.en
dc.description.abstract(g) With the empirical staining methods the appearance and distribution of the enteric plexuses was essentially similar to that demonstrated by the histochemical methods. A wide variation in the staining reactions of the enteric perikarya with the silver technique was observed, argyrophobic and argyrophilic multipolar neurons and argyrophobic unipolar neurons being demonstrated. The argyrophilic nerve cell bodies corresponded to Dogiel's type I, II and III neurons.en
dc.description.abstract(h) These observations were discussed in the light of the available histological evidence of the innervation of the gut in birds and other classes of vertebrates.en
dc.description.abstract5. The number and size of the perikarya in the myenteric plexus of three immature and three mature birds was estimated in strip and whole mount stretch preparations using the histochemical technique for detecting NADH-diaphorase activity. (a) In the chicks and adults the mean neuron density per cm and the total number of the cells in each region increased distally. The difference between the counts in adjacent regions were generally 2 significant. With age the neuron density per cm decreased and the absolute number of neurons increased. The mean neuron density in each region in the chick was two to three times higher than in the 2 adult. The neuron density per cm was significantly greater in the mesenteric zone of the plexus. The calculated total number of cells in the adult was significantly higher than in the chick. (b) The size of the neurons varied in the different regions of the intestines and increased with age. In both the chick and adult the largest neurons were present in the distal part of the caecum. 0 Small-sized neurons were present in the chick and adult although they were especially numerous in the chick. (c) The differences in neuron density and estimated cell sizes between the chicks and adults were discussed and compared with similar data in other vertebrates.en
dc.description.abstract6. The ultrastructure of the myenteric and submucosal plexuses was investigated in male and female, immature and adult birds. (a) The ganglia consisted of a dense neuropil consisting of nerve cell bodies, myelinated and unmyelinated axons, Schwann cells and satellite cells. At the outside of the ganglia was a basal lamina and dense connective tissue containing fibroblasts, interstitial cells and blood vessels. Whilst most of the nerve cell bodies were covered by satellite cells, a part of some of them lay directly under the basal lamina; (b) The perikarya displayed the basic structural features of nerve cell bodies. The majority of them had a small number of randomlydistributed granular vesicles. (c) Small and large axon profiles were identified. Small axon profiles contained mainly microtubules and neurofilaments, whilst larger profiles contained mainly granular and agranular vesicles. Three types of varicosity were described. One type of varicosity contained numerous small agranular vesicles which were sometimes intermingled with medium-sized granular vesicles. This axon profile was probably cholinergic. A second type of varicosity contained small granular vesicles and small agranular vesicles and was probably adrenergic. The third type of axon profile contained numerous small agranular vesicles, many large granular vesicles and a few small granular vesicles. The possibility was considered that this type of varicosity was adrenergic. All three types of varicosity formed typical motor synapses with the neurons. At the synaptic junction only agranular vesicles were associated with the presynaptic membrane of the axon. (d) The structure of the Schwann cells and satellite cells was essentially similar. The perikarya of the Schwann cells gave rise to long, attenuated processes which ensheathed many axons. Structurally, the interstitial cells resembled fibroblasts. (e) The findings were discussed in relation to the available ultrastructural information in other classes of vertebrates.en
dc.description.abstract7. The difficulties in interpreting the present observations in the light of the available information on intestinal motility were outlined. The findings emphasized the urgent need for electro physiological studies on the avian enteric plexuses.en
dc.publisherThe University of Edinburghen
dc.relation.ispartofAnnexe Thesis Digitisation Project 2018 Block 18en
dc.relation.isreferencedbyAlready catalogueden
dc.titleLight microscopic and ultrastructural studies on the enteric nerve plexuses of the domestic fowlen
dc.typeThesis or Dissertationen
dc.type.qualificationlevelDoctoralen
dc.type.qualificationnamePhD Doctor of Philosophyen


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