The Postcentral gyrus of the brain of the cat has been studied with the technics of Nisel and Golgi. Qualitative data concerning packing densities and volumes of the nerve cells and of the glia, as welll as the distribution of the dendrites are reported. The existence of alternate dendritic and axonal layers has been demonstrated and the relationship of these layers to the stripes of Baillarger has been analyzed. / fr

No description available.

Fresh and prepared museum specimens of the white shark Carcharodon carcharias, bull shark Carcharhinus leucas, and salmon shark Lamna ditropis were measured and compared with respect to tooth position and anterior buccal cavity dimensions. Coordinates of functional tooth position were defined by 1) deviation from the midline and 2) degree of erection. Tooth positions were not unique in any region of the mouth/ but demonstrated less variablity within 30° of the midline, particularly for male specimens of all three species (71.48° +- 10° erect) and all Carcharhinus leucas specimens (46.58° +-.96° erect). Analysis of high-speed videotape of white shark feeding indicated a 15.7° reduction in tooth cutting angle with jaw adduction following upper jaw protraction. It is suggested that such changes in tooth cutting angles during feeding are principally the result of jaw flexure, and may make the teeth more effective by angling them inward towards the gullet. Values for tooth removal from fresh-frozen white shark material using a tensile testing apparatus ranged from 12 kg (for a 110° erect tooth) to 70 kg (for a 59° erect tooth). Removal load was applied directly outward from the mouth to simulate a resistant prey item, and was not significantly different for degree of erection or tooth position on the jaw margin. Tooth position is seen to change with jaw protraction, however this change does not enhance tooth functionality by increasing the load required to remove the tooth. / Science, Faculty of / Zoology, Department of / Graduate

A thesis submitted to the Faculty of Dentistry, University of the Witwatersrand, Johannesburg, for the Degree of Doctor of Philosophy. 1993 / Three-dimensional forensic facial reconstruction involves the building up in clay of the soft tissues of the human face onto an unidentified skull to suggest the identity of its owner. Early researchers physically punctured the facial tissues of cadavers at known anthropological to measure their depth. Later workers used radiography, ultrasonography and magnetic resonance imaging for collecting both depth and surface data on the head and face. / GR 2016

Indiana University-Purdue University Indianapolis (IUPUI) / Eighteen adult human skulls with "normal occlusion" were examined with oriented lateral, 15, 25, 45, 75, and 90 degree cephalograms from which the mesio-distal axial inclinations of the teeth were measured. This study indicates that a large variation of the mesio-distal axial inclinations of the teeth may occur and still have a "normal occlusion". The standard deviations varied from a maximum of 11.0 degrees for the maxillary third molar to a minimum of 3.4 degrees for the maxillary cuspid. Rotation of the midsagittal plane of the head with the film effected the measurements of the maxillary first molars and cuspids, and the mandibular bicuspids by producing divergence of their roots on the film image. No relationship was found between measurements of this sample and measurements of mandibular plane, A-B plane, Y-axis, facial angle, angle of convexity, Down's occlusal plane, lower incisor - A-Pg, and interincisal angle. A positive relationship was found between the measurements of this sample and the posterior one-half of nasal floor, posterior occlusal plane, and the labiolingual axial inclination of the lower incisor.

by Shuk-man Yuen. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1991. / Bibliography: leaves 108-121. / Chapter CHAPTER 1 --- INTRODUCTION / Chapter 1.1 --- General Introduction --- p.1 / Chapter 1.2 --- Neural Regulation of Muscle Development --- p.3 / Chapter 1.3 --- "Changes in Motoneuron Number, Motoneuron Properties and Innervation during Development" / Chapter 1.3.1 --- Decrease in Motoneuron Number --- p.6 / Chapter 1.3.2 --- Reduction of Synaptic Connections --- p.7 / Chapter 1.3.3 --- Changes in Motoneuron Properties during Development --- p.9 / Chapter 1.4 --- Neural Influence on Muscle Properties in Adult Mammals / Chapter 1.4.1 --- Effect of Denervation on Muscle Properties --- p.10 / Chapter 1.4.2 --- Plasticity of Muscle Properties --- p.12 / Chapter 1.5 --- Partial Denervation --- p.15 / Chapter CHAPTER 2 --- MATERIALS AND METHODS / Chapter 2.1 --- General Plan --- p.22 / Chapter 2.2 --- Normal Unoperated Group / Chapter 2.2.1 --- Innervation of the SOL and EDL --- p.23 / Chapter 2.2.2 --- Tension Recordings --- p.24 / Chapter 2.2.3 --- Contributions of L4 and L5 to Normal Tension of the SOL and EDL --- p.26 / Chapter 2.3 --- Young Denervated and Adult Denervated Groups / Chapter 2.3.1 --- Unilateral Partial Denervation --- p.27 / Chapter 2.3.2 --- Tension Recordings --- p.28 / Chapter 2.3.3 --- Measurement of Contraction and Relaxation Speeds --- p.28 / Chapter 2.3.4 --- Recovery in Tension of Partially Denervated Muscles --- p.29 / Chapter 2.3.5 --- Motor Unit Number and Size --- p.29 / Chapter 2.3.6 --- Resting Membrane Potential --- p.31 / Chapter 2.3.7 --- Histometric Analysis and Histochemical Study --- p.32 / Chapter 2.3.8 --- Immunocytochemical Study on Different Types of Myosin --- p.34 / Chapter 2.3.9 --- Histological Study on Innervation of Muscle Fibres --- p.35 / Chapter 2.4 --- Retrograde HRP Labelling for HRP Group --- p.37 / Chapter 2.5 --- Statistic Analysis --- p.39 / Chapter CHAPTER 3 --- RESULTS / Chapter 3.1 --- Contribution of Spinal Nerves to Tension in Normal Unoperated Group --- p.44 / Chapter 3.2 --- Results from Young Denervated and Adult Denervated Groups / Chapter 3.2.1 --- Recovery in Tension --- p.45 / Chapter 3.2.2 --- Changes in Other Contractile Properties --- p.48 / Chapter 3.2.3 --- Motor Unit Number and Size --- p.49 / Chapter 3.2.4 --- Resting Membrane Potential of Adult Denervated Group --- p.51 / Chapter 3.2.5 --- Changes in Cross-sectional Area of Whole Muscle and Number of Muscle Fibres --- p.52 / Chapter 3.2.6 --- Histochemical Properties and Types of Myosin --- p.53 / Chapter 3.2.7 --- Histological Study on Innervation of Partially Denervated Muscles --- p.56 / Chapter 3.3 --- Results of HRP Group --- p.58 / Chapter CHAPTER 4 --- DISCUSSION / Chapter 4.1 --- Contribution of Spinal Nerves to Tension Development --- p.91 / Chapter 4.2 --- Recovery of Partially Denervated Muscles --- p.93 / Chapter 4.3 --- Time Courses of Functional Recovery --- p.98 / Chapter 4.4 --- Effect of Partial Denervation on Properties of Muscles --- p.100 / Chapter CHAPTER 5 --- CONCLUSION --- p.106 / REFERENCES --- p.108

No description available.

A study of muscle spindles in two synergistic avian muscles was undertaken to determine whether morphological or quantitative differences existed between muscle spindles residing in a slow-red (tonic) muscle and a fast-white (twitch) muscle. The avian anterior (ALD) and posterior (PLD) latissimus dorsi muscles were chosen since they are unique among vertebrates as paradigms of a slow-red and a fast-white muscle respectively. Serial frozen sections of muscle were stained with Haematoxylin and Eosin or Gomori triehrome and muscle spindles residing in the ALD were assessed and compared with those in the PLD with regard to organization, distribution and density, Contents of muscle spindles were examined for intrafusal fibre size, number and morphology. Attention was also directed to the relationship between muscle spindles and the surrounding extrafusal muscle in which they were located. Differences were found between muscle spindles residing in the two muscles. In the slow ALD, muscle spindles were relatively evenly distributed, whereas in the fast PLD, they were concentrated around the single nerve entry point into the muscle. The ALD muscle spindle index was the highest yet published for chicken muscle and was 2.3 times higher than that of its fast counterpart. A bimodal trend in intrafusal fibre diameter was noted in the ALD, and a trimodal trend was found in the PLD. The former had 42% fewer intrafusal fibres than the latter. Muscle spindles were shorter in the ALD, with an average length of 1.9mm compared with 2.3mm in the PLD. An interesting feature of the slow muscle was the monofibril muscle spindle, containing a single intrafusal fibre. With a few exceptions, ALD muscle spindles were located within the interfascicular perimysium close to a neurovascular trunk. PLD muscle spindles were rarely seen in these areas but were frequently found within a muscle fascicle, surrounded by closely apposed extrafusal fibres. Moreover, neurovascular trunks were less frequently seen in the PLD. As an adjunct to this study, three ALD-PLD pairs from the Storrs Connecticut strain of muscular dystrophic chickens were also examined to compare muscle spindles in these muscles with those of normal animals. In the PLD, which is known to exhibit early and progressive pathological change, muscle spindles appeared relatively normal until marked extrafusal fibre degeneration had occured. By this time evidence of muscle spindle involvement included capsular hypertrophy and intrafusal fibre splitting. Whereas the slow ALD has been reported to retain apparent normalcy in muscular dystrophy, subtle changes were seen in some of the muscle spindles examined. These included an increase in number of intrafusal fibres per muscle spindle compared with those in the normal. / Land and Food Systems, Faculty of / Graduate

In this study, I consider the comparative and functional anatomy of cerebrally related retial systems in the two constituent species (Monodon monoceros and Delphinapterus leucas) of the family Monodontidae (order Cetacea). The internal carotid arteries, the "classical" vessels of cerebral supply in vertebrates, are completely non-functional as cerebral supply vessels in the Monodontidae. Moreover, there are no other channels that contribute directly to intracranial supply. Rather, the brain, or more precisely, the entire central nervous system, is vascularized indirectly via an extensive arterial plexus or rete mirabile. This plexus is found in the thorax, lumbar region, neural canal and cranium. Vessels that contribute to retial formation are numerous and include those which in other mammals contribute directly to supply of the central nervous system and/or its membranes. Efferent retial vessels are few and include two pairs of subdural intracranial trunks that supply the brain, and numerous small segmental vessels that penetrate the spinal dura and vascularize the spinal cord. Subdural arterial circulation in the Monodontidae is modified after the basic mammalian pattern. Within the cranium, it is characterized by: (1) an incomplete circle of Willis (due to (a) independence of the anterior cerebral arteries and (b) the lack of anastomoses between the two pairs of trunks which take origin from the rete), (2) extensive cortical supply by the anterior choroid arteries, and (3) absence of a vertebral basilar system. Subdural arteries coursing to the spinal cord do so mainly between successive ventral spinal roots. An A. radicularis magna is not evident, nor are anterior or posterior spinal arteries. Hence, there are differences between the subdural circulatory patterns in the Monodontidae and those in other mammals, however the major site of vascular modification is epidural with formation of the rete mirabile. Though gross retial anatomy is the same in Monodon monoceros and Delphinapterus leucas, and is generally similar to that described for other odontocetes, there are two related characteristics that appear species specific: thoracic retial size and the number of intercostal spaces supplied by the supreme intercostal arteries. Both are larger in Monodon monoceros, as are hematological values (hematocrit and hemoglobin concentration) which, in this study, are used as indices of diving ability. These data are consistent with the hypothesis that cerebral related retia in the Cetacea are related to the diving habit. Microscopically, the rete generally consists of small muscular arteries embedded in fatty connective tissue interlaced with a few nerve trunks and veins. Arterial walls are characterized by a distinct internal elastic lamella, a tunica media of 12-14 layers of vascular smooth muscle, and an adventitia of alternating layers of collagen and elastin. Retial arteries are at best poorly innervated. The substructure of retial arteries resembles that of other mammalian arteries except for the presence of large deposits of glycogen (alpha particles) in vascular smooth muscle and endothelial cells. On the basis of this observation, and theoretical considerations, I generate the hypothesis that the rete may contribute to blood glucose levels during a dive. This hypothesis could not be tested directly, hence I chose an indirect approach involving biochemical and ultrastructural analyses. I conclude that free glucose release is not a major function of the rete since: (1) G-6-phosphatase activities are low, (2) LDH electrophoretic profiles suggest that most stored glycogen is used intrinsically, and (3) I could not demonstate glycogen deposits in retial vessels of other species. All proposed retial functions are evaluated, and I conclude that the system probably functions in a mechanical way (pressure reservoir) and that it does so passively. / Science, Faculty of / Zoology, Department of / Graduate

Submitted in fulfilment of the requirements for the degree of Ph.D in the F culty of Science, University of the Witwatersrand, Johannesburg. February 1957. / The roles played by fibrous proteins in nature are at present being intensively studied and some of the advances in our knowledge of these proteins are the subject of several recent symposia. (la,b) The powerful techniques of X-ray diffraction end electron— optic analysis as well as ran unprecendented improvement in the specificity and accuracy of chemical and chromatographic methods of analysis has led to ever increasing efforts to interpret biological phenomena within a framework of physicochemical principles. In many fields, particularly those of virus research and muscle contraction these efforts have already been rewarded by a large measure of success. In the present work, which forms part of a program of research into the chemistry of connective tissues of man and other vertebrates, the chemical properties and structural features of the extracellular collagenous proteins in some calcified and uncalcified connective tissues are compared. 'In vivo' calcification of connective tissue is generally thought to be the result of a physico-chemical combination between lima salt3 and the organic matrix mediated by the ionic and structural prop rties of the matrix and the activity of various cello and enzymes / IT2017