Functional and developmental morphology最新文献

In the present paper the ultrastructural similarities among the terminal portions of Pacinian corpuscles, the nodes of Ranvier, and the initial segments of primary sensory neurons are pointed out. Our conclusion is based on our observations of cat Pacinian corpuscles and other general knowledge of the node of Ranvier and the initial segment published elsewhere. The morpho-functional similarities of three principal excitable regions of the sensory nerve fibres (the initial segments, the node of Ranvier, and the terminal portions of sensory nerve formations) are illustrated by identical distribution of the enzymes which are associated with ionic transport (alkaline phosphatase, Mg(2+)-ATPase), and non-specific cholinesterase. Furthermore, the polyanionic material revealed by Alcian blue staining in three excitable sites of the sensory axon confirms the supposition that excitable axolemma cannot be considered in the isolation of its surroundings produced by Schwann cells.

The distribution of nigral neurons retrogradely labelled from the globus pallidus was studied in 9 rats using the horseradish peroxidase and the iron-dextran labelling technique. Retrogradely labelled neurons significantly prevailed in the ipsilateral substantia nigra pars compacta. Labelled neurons localized in the ipsilateral substantia nigra pars compacta were demonstrated throughout the anteroposterior extent of the nucleus and prevailed in its lateral half. A small number of labelled neurons was found in the lateral part of the ipsilateral substantia nigra pars reticulata, in the ipsilateral ventral tegmental area and in the contralateral substantia nigra pars compacta. A considerable perikaryal polymorphism and differences in the size are characteristic of the nigral neurons labelled from the globus pallidus.

The cancellous bone architecture in man is locally specific. Several principal types can be distinguished, depending on the kind of loading and movement in the joint in one, two or more directions. Under multidirectional load the spongiosa trabeculae form spatial fans seen as two crossing systems on plane sections. Marked differences exist between the bone structure under concave joint surfaces and the convex ones. The analysis testifies the correctness of the author's own theory on the development of the cancellous bone architecture. According to this theory every trabecular system corresponds to other direction of maximal principal stress in the course of movement. Both crossing systems in the metaphysis are pressure systems, corresponding to opposite extreme positions in the joint. Tension systems can be found in sites of ligament or tendon insertions and closely under concave articular surfaces only.

The fact that calcium ions regulate the secretion of thyroid hormones could be extended to explore how the mechanisms of anuran metamorphosis is controlled by thyroid hormones. In the present study, an attempt was made to investigate the effects of both calcium channel blocker, Diltiazem (DT) and calmodulin inhibitor, Trifluoperazine (TFP) on metamorphosis and various developmental stages of the anuran tadpole, Rana tigerina. Both DT (25 microM) and TFP (2 microM) treatments caused total inhibition of the development and metamorphosis of the tadpole at premetamorphic stages. The metamorphosis was delayed by DT and totally inhibited by TFP when tadpoles were exposed at prometamorphic stages. Both drugs could not affect the tadpoles at climax stage. The findings suggest an active involvement of thyroid hormone in premetamorphic tadpoles. Calcium channel blockage with DT could not prevent the progression of tadpoles through prometamorphic stages which suggest that the change in calcium pool is not a determining factor mediating thyroid hormone release mechanism. The study suggests that in tadpole growth thyroid hormone secretion is modulated by calmodulin bound intracellular calcium.

In this study of the human palatine tonsil we examined epithelial structures found always in the vicinity of the crypts and closely resembling thymic Hassall's corpuscles. We propose that in the reactive tonsillar lymphoid tissue these corpuscles form as a result of occlusion of fine microcrypts by the expanding lymphoid follicles during antigenic stimulation. The reticulated epithelial cells lining these microcrypts may then loose their polarisation, and gradually degenerate deep in the parenchyma, forming concentrically arranged parakeratotic pearls, rather than desquamate at the free epithelial surface. The structural similarities of the tonsillar and Hassall's corpuscles may be explained by endodermal embryological origin of the primordia of both organs, and by the specific degenerative properties of epithelia in the lymphoepithelial immune organs.

Morphological changes in the thyroid glands of the guinea pigs with autoimmune thyroiditis (EAT) experimentally induced by thyroglobulin (TGL) or immunization by the suspension of thyroid gland cells with CFA manifested mainly by atrophy and alterations of follicular cells, fibrotic tissue changes, formation of inflammatory lymphoplasmocytic infiltrations, multiplication of C-cells and by the increase in the proportion of lymphocytes with activated nucleoli in the tissue. The antigenic effects of TGL differed from those of the cell suspension; the effects of TGL participated especially in the formation of the infiltrates, the effects of cell suspension participated in the diapedesis of mononuclears and in the multiplication of C-cells. The findings correspond to the principal findings in human autoimmune lymphocytic thyroiditis. In an electron microscope, strongly dilated cisterns of endoplasmic reticulum (ER) and multiplied mitochondria in the cytoplasm of altered follicular cells were found. The wall of the follicles exhibited fully intact or altered C-cells. The latter had a large number of granules in cytoplasm with an unusually clear medullary substance. In the rabbit thyroid glands no morphological changes were observed following the immunization with both antigens. TGL antibodies examined immunohistochemically in the sera were present in all the sera of guinea pigs immunized with TGL and CFA. The antibodies determined by dot immunodetection were present in the sera of all guinea pigs immunized with TGL+CFA, the titres reached the level of 1:81 to 1:729; the highest titres were observed in the guinea pigs following the immunization by dose of 7.7 mg/kg after 12 weeks of immunization.

The morphological changes in rabbit pancreases after duct ligation were studied. These changes do not occur synchronically within the whole pancreas. The most advanced are those in the head portion; in the tail, their development is delayed. Pancreas duct ligation results in the pancreas edema, a gradual disappearance of zymogenous cells, replacement of acini by small ducts, an occasional differentiation of new zymogenous cells that quickly extinct again, and with the occurrence of amorphous or even fibrillary masses in the cytoplasm of duct cells to their further reduction. These changes are accompanied by the formation of loose connective tissue which gradually fibrotizes. The islets of Langerhans also undergo changes. In the tubules, a differentiation appears of their cells into endocrine elements. The existing islets get destroyed by both the fibrotic tissue and the formation of cavities in large islets with a consequent break-up of those islets. Both these destructive processes, in connection with the new formation, result in the appearance of small islets on the surface of which there is a capillary network. The cells of those islets are not of a fetal character.

Changes of morphometrical, biochemical, histochemical and immunohistochemical parameters were investigated in the alloxan diabetes in the dog. Samplings of material for electron microscopical and histochemical examinations were performed in 3 month period (4 times). A significant thickening of capillary basement membranes in the striated muscle (vastus lateralis) was ascertained even in the dog with glucose intolerance only. In this mentioned case a decrease of glucoso-6-phosphatase activity was observed. Evaluation of different types of muscle fibres assigned an increase of slow twitch fibres or intermediate ones respectively.

A new applicability of the suppressive Nauta impregnation method was tested allowing the detailed mapping of early neuronal damage expressed in the form of somatodendritic argyrophilia. Two spinal cord ischemia-reperfusion models of rabbit and dog, a model of canine global brain ischemia-reperfusion, involving cardiac arrest followed by resuscitation, and a canine spinal cord compression-decompression model were used. Early phases of neuronal damage are characterized by conspicuous somatodendritic argyrophilia permitting an exact evaluation of acute neuronal damage according to soma size, dendritic ramifications and localization of the affected neuronal neuronal pool. By its high sensitivity to somatodendritic damage the suppressive Nauta method appears to be a valuable neuropathological technique.