During a study of the morphology of the orthopteroid Hexapoda between the years 1939-1941, it appeareded to the writer that further investigation into the structure of the insect tentorium was necessary. The early entomologists laid the foundation or our knowledge or the tentorium but during the latter half of the last century little was added in this particulart field. Comstock and Kochi (1902), as far as the writer is aware are the only workers who have published a paper devoted entirely to the skeleton of the bead of insects, and they did much to clarify both nomenclature and existing knowledge of this structure at that time. Berlese (1909) described a typical tentorlum as observed in orthopteroid Hexapoda and then considered the variations of the tentorium which occur in other groups of insects. Some confusion then appears to have arisen amongst workers, over the origin of the dorsal arms which were erroneously considered by some to be cuticular invaginations and not secondary outgrowths of the anterior tentorial arms. Certain morphologists amongst them, Hoke (1924) Denis (1928), Snodgrass (1928, 1935), Hansen (1930), Walker (1933) Imms (1934), and Symmons (1952), have done much towards improving our knowledge of the tentorium, but all too frequently workers offer brief and inadequate descriptions of this structure in otherwise comprehensive investigations of the insect head. Themain objects in this study are threefold, vlz. (1) The claification of nomenclature (2) The examination and the interpretation ot the tentorium in certain groups of insects. (3) The deliberation as to whether the tentorium is of phylogenetic significance, and thus of use in assessing various schemes of insect classification which have been presented. Introduction, p. 1-2.

In this thesis the interest has centered mainly on the comparative anatomy of the lateral eyes of Arthropods especially the compound eyes, with some particular reference to those of Chilopoda. The comparative anatomy of the eyes of Chilopoda seemed to be of interest, since they possess in most cases simple lateral eyes, which are not characteristic of the adults of any other group of Arthropoda, except Arachnids, to which the Chilopoda are only remotely related In a few cases - in the Scutigeridae - "compound" eyes are present, which are very unusual in their internal anatomy. The following possibilities with regard to the relationships of the Chilopod eyes present themselves. The simple eyes may be the products of degeneration of a compound eye. Alternatively they may be ocelli of a very primitive pre-compound eye type, persisting where in some cases a compound eye has failed to develop. As a third possibility they may have been separately evolved in forms, in which the compound eye was lost or failed to develop. In the last case they would appear to be unrelated to those of any other Arthropods, except possibly those of Diplopods, to which they are very similar in structure. The "compound" eyes may be or the same type as the compound eyes in the remaining Arthropods, with the differences due to degeneration, or to specialisation. Alternatively they may be of a separate type and formed secondarily, either as a single new structure. or a coalescence of ocelli. The enquiry into the interrelationship of these eyes and their relation to the eyes of other Arthropoda raises several points for investigation. For the compound eyes it is necessary to decide whether they were primarily present in the ancestors of some or all of the classes or Arthropods, and whether they have a common or more or less diverse origin with some evolutionary convergence. For the lateral simple eyes it is necessary to decide whether there are any indications in phylogeny, ontogeny or anatomy of the primitive or secondary formation of a compound eye by the aggregation of numerous ocelli or the elaboration of one or these. Such information might be expected to throw light on the origin of the Scutigerid eye. Alternatively any indications of the formation of simple from compound eyes might show whether the Chilopod simple eyes could have evolved in this way from a Scutigerid or some other compound eye. Median eyes are present in some Trilobites, Eurypterida, Crustacea, Hexapods and Arachnida. Although they exhibit considerable variations in structure, they are all clearly simple eyes. As they are absent in Chilopoda and in the remaining Arthropods are entirely separate in origin from the lateral eyes, with a separate seat of innervation, their comparative anatomy is of little interest in this case. The main portion of the thesis deals with the comparative anatomy, origins and relationships of the different types of compound lateral eyes. The second part comprises a short appendix dealing with similar aspects of the lateral ocelli. Detailed descriptions and figures have been given for the eyes of eight species. Some mention is also made of points observed in the internal or external anatomy of species which were studied in less detail. The theoretical conclusions are based on material from the available literature and from these descriptions.

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The purpose of this study was to describe the functional role of the lower limb musculature during stationary cycling using electromyography, muscle-tendon unit length changes, and segmental kinematics. Five subjects were filmed (100 Hz) in synchrony with the collection of LE EMG activity of the gluteus maximus, semitendinosus, semimembranosus, rectus femoris, vastus lateralis, soleus, gastrocnemius, and tibialis anterior muscles during stationary cycling at 160 W (90 r/min). The results showed that extension during the propulsive phase of the pedal cycle was the result of high concentric activity of both the monoarticular and biarticular muscles. Furthermore, these muscles functioned according to their expected anatomical roles (Rasch and Burke, 1978). This investigation, therefore, finds little evidence for the existence of paradoxical muscle function as hypothesized by Lombard (1903), Molbech (1965), or Rasch & Burke (1978).

In filming and digitizing human segmental motion, external markers do not necessarily represent a true picture of the actual bone movement. When surface markers are placed on the skin or skate boot (in ice hockey) they move according to skin or boot movement, which does not exactly match bone movement. This results in a misrepresentation of the joint axes of rotation and a greater margin of error in motion measurement and analysis. This problem occurs for ankle and foot movements as their motion is quantified about the ankle joint complex (talocrural and subtalar joints). Hockey skates are vastly more rigid than regular shoes and their restriction of foot movement is greater. Therefore, shoes and hockey skates cannot be considered identical. The present study aims at exploring differences amongst bone, skin, and skate marker based motions of the foot during skating. (Abstract shortened by UMI.)

Polynomial regression was used to describe the relationship between lengths of the five muscles of interest and lower extremity joint angle(s). A difference between the genders was observed, so the male and female data were separated and five regression equations (one per muscle) were fitted to each data set. In an attempt to build general regression equations normalization and transformation of the data was performed, but these manipulations of the data did not lead to predictive equations. Addition of leg segment length, for the monoarticular muscles, and height, for the biarticular muscles, as independent variables did significantly increase model fit. The general regression model was quantitatively compared to the leg segment lengths and the actual observed values. It was also qualitatively compared to two other models. Results showed that while the general regression model is good at predicting muscle function, it is not a very accurate predictor of muscle length.

Accumulating biochemical and morphological evidence suggests that apoptosis contributes to neuronal cell death following cerebral ischemia. Recent research which has examined changes in expression of proapoptotic proteins has further strengthened the important role of apoptosis in ischemic cell death. In this thesis I first addressed the role of apoptosis in ischemic death by examining p53, which is itself a complex multifunctional tumor suppresser gene, following transient focal ischemia. Of particular note were the alterations of the anti-apoptosic gene, naip, that were observed under stress conditions. The anatomical distribution of naip expression and neuronal survival following middle cerebral artery occlusion (MCA-o) were closely examined. In experiment I, SHR rats were subjected to 90 minute MCA-o followed by 22.5 hr reperfusion (RP) and compared with sham operated controls. In experiment II, sections obtained from fresh frozen or fixed brain tissue of long-Evans hooded rats (n = 3--4) that had been subjected to hippocampal kindling were used for ISHH or immunohistochemistry for naip expression. Neuronal protection against cerebral ischemia by hippocampal kindling was assessed in experiment III. Hippocampal kindled animals were also used to study the time course of naip expression in the frontoparietal cortex, which is mainly supplied by MCA. Both p53 mRNA and protein were elevated in the ischemic penumbra in experiment I. The induction of p53 peaked within 8--12 hr then returned to basal levels within 24 hr after RP. The short duration of p53 induction in ischemic penumbra may suggest that p53 activate downstream genes responsible for growth arrest, DNA repair or/and apoptosis. Experiment II demonstrated a significant elevation in naip mRNA and proteins in piriform cortex and hippocampus, where neuronal populations known to be protected by kindling. The duration of the elevation lasted up to three weeks. In contrast, naip mRNA and protein remained at baseline levels in regions that are not protected, such as endopiriform cortex and medial thalamus. We also demonstrated that hippocampal kindling attenuated cortical infarct induced by MCA-o to 57.7 +/- 4.6mm3 as compared to 156.5 +/- 12.6mm3 in controls. This neuroprotection was associated with a two to three fold elevation of naip expression in the corresponding areas by kindling treatment. (Abstract shortened by UMI.)

The main objective of this project was to master the electron probe x-ray microanalysis technique to permit one to obtain physiologically meaningful quantitative elemental profiles (Na, Cl, K, P, Mg, Ca & S) for the components of a given cell. The techniques which had to be mastered were: preparation of mammalian (rat) cardiac muscle; 'rapid' cryofixation using a Reichert-Jung MM80E 'impact freezer'; cryosectioning using a Reichert-Jung FC4 cryoultramicrotome; transfer and freeze-drying; electron probe x-rays collection using the EDAX 9100 Series Energy Dispersive X-ray Analysis Systems attached to a Philips TEM 420; quantitative analysis using the Hall equation and thin membrane aminoplastic standards. Different methods of transfer and freeze-drying were compared. Method I-a. Cryotransfer to the electron microscope using a modified Philips Cryotransfer system, freeze-drying in the column of the electron microscope, x-rays collection at low temperature; Method I-b. Cryotransfer to the electron microscope using a modified Philips Cryotransfer system, freeze-drying in the column of the electron microscope, x-rays collection at ambient temperature; Method II. Cryotransfer to a vacuum chamber (Edward-Coating System E306 A) using a precooled metal carrier, freeze-drying in a vacuum chamber while warming at ambient temperature, transfer and x-rays collection at ambient temperature. (Abstract shortened by UMI.)

An ultrastructural study using electron microscopy was undertaken of yolk and yolk sac to elucidate digestive mechanisms and to gather evidence to further substantiate the belief that intracellular digestion of yolk takes place in yolk sac epithelial cells during incubation. Initial work focused on the ultrastructure yolk in unincubated eggs using transmission electron microscopy of thin sections of yolk which had been fixed using conventional and novel fixatives. The next phase of the study involved the ultrastructural comparison of granules from sub-blastodermic fluid from 9 day old embryos, and extracellular yolk attached to the yolk sac of 15 day old embryos with the granules from yolk of unincubated eggs. The third phase of the study was the ultrastructural description of yolk sacs at 3 ages (3 days, 8 days and 15 days of incubation). A transport system for yolk lipid and its digestion products to the embryo was demonstrated ultrastructurally using the Imidazole-buffered Osmium Tetroxide protocol of Angermuller and Fahimi (1982) which enhanced lipid staining. We observed no ultrastructural changes in extracellular yolk granules and matrix particles at any age studied. Granules and matrix particles are taken up by endocytosis, and ultrastructural changes of yolk granules occur in epithelial cells, in acid phosphatase-containing vacuoles (which we have identified as secondary lysosomes), which are part of the functioning intracellular digestive system. We have ultrastructurally demonstrated the transport of lipids, which becomes more evident in 13 day old embryos. On the basis of the above evidence we conclude that yolk is digested in epithelial cells of the yolk sac, and the digestion products enter the blood sinuses and travel in the bloodstream to deliver nutrients to the developing embryo. (Abstract shortened by UMI.)

To study the stimulating effects of retinoic acid on the primary culture of immature rat hepatocyte, we examined the changes in the bile canaliculi formation by observing the cytokeratins 55 kDa and 49 kDa. The formation of the bile canaliculi sheaths was our end point of differentiation. We obtained monolayer hepatocyte culture from 14-day old male Wistar Charles River rats, using the two-step collagenase perfusion method of Seglen (1976), as adapted to preweanling rats by Deschenes et al (1980). All-trans retinoic acid 10$\sp{-5}$M dissolved in 0.1% dimethyl sulfoxide was added to the treated cultures. All cultures were maintained for 48 hours. The organization of cytokeratin was visualized by immunofluorescence using monoclonal antibodies to cytokeratins 55 kDa and 49 kDa. Under the influence of retinoic acid, the number and size of bile canaliculi formed were significantly increased. The bile canaliculi formed and a more complex architecture, such as ramification. Theses observations were confirmed by un-embedded whole mount electron microscopic studies on detergent extracted preparations. In retinoic acid treated colonies, the bile canaliculi appear to be functional as demonstrated by the cellular uptake followed by polarization and secretion of the fluorescein diacetate dye. Gel electrophoresis showed an apparent disparity in the relative quantity of cytokeratin 55 kDa and 49 kDa, especially in the control group. This inequality may be attributed to a selective increase in proteolysis during preparation. It is concluded that the addition of retinoic acid to the media stimulates the differentiation in hepatocyte monolayer cultures. It is possible that retinoic acid induces modification in the hepatocyte gene expression and the formation of bile canaliculi could be associated with changes in the expression of the cytokeratin genes. The two cytokeratins would be coexpressed in response to the treatment with retinoic acid.