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Biomedical subjects

G L Scott

Publications and source records attributed to G L Scott.

At least 37 records · Page 2Linked to original sources
PubMed1983

Ultrastructure of the placenta and fetal membranes of the dog: II. The yolk sac.

Yolk sacs from dogs at 40, 50, and 60 days of gestation were examined by electron microscopy. Free ribosomes, mitochondria, and rough endoplasmic reticulum (rER) are more prominent in both endoderm and mesothelium at 40 and 50 days than at 60 days, suggesting a greater synthetic capacity at the earlier stages. Smooth endoplasmic reticulum (sER) and glycogen are also present in greater amounts in the endoderm in the earlier stages. In the mesothelium, however, low amounts of sER and glycogen are consistently present. Certain possibilities relative to the nature of the synthetic activities in these two tissues are discussed. Large amounts of smooth-surfaced vesicles were observed along the basal edges of the 60-day mesothelium; they are indicative of transport processes occurring at this time. As gestation proceeds, in both endoderm and mesothelium, the Golgi complex remains well developed, there are more numerous lysosomelike bodies, and bundles of intermediate filaments either increase or become more diffused. In some endoderm cells at 60 days, large vacuoles and dense glycogen deposits were noted. These observations indicate that degenerative processes are gradually occurring in the endoderm and mesothelium as parturition draws near. Erythropoiesis occurs in the mesenchyme at 40 and 50 days. At 40 days also, segments of endothelium were seen within blood islands, indicating that the endothelial lining of some yolk sac vessels differentiates from cells located in the interior of such islands.

Animals↗
PubMed1983

Heparin-associated priapism.

A patient who developed priapism 7 hr after stopping an intravenous heparin infusion is described. Abnormal spontaneous platelet aggregation was demonstrated whilst on heparin treatment and is thought to play a role in the aetiology of heparin induced priapism.

Adult↗
PubMed1983

Ultrastructural identification of satellite interneurons in the rat dorsal lateral geniculate nucleus.

Multiple injections of horseradish peroxidase (HRP) were placed in the occipital cortex of rats, including all striate and extrastriate visual areas, to examine with the electron microscope the population of retrogradely labeled and unlabeled cells in the dorsal lateral geniculate nucleus (LGN), for the purpose of ultrastructurally identifying geniculate interneurons. O-tolidine was used as chromogen in the histochemical procedure. EM analysis of LGN showed dense HRP reaction products diffusely distributed in the cytoplasm of virtually all large and medium size geniculate cells, identifying the geniculo-cortical relay cells. The classes of unlabeled cells distinguished in this study are oligodendrocytes, astrocytes, and other small cells whose glial or neural nature is difficult to assess in light microscopic semithin sections. In serial ultrathin sections, these small cells were seen to be presynaptic in somato-somatic synapses with relay cells, and to give origin to presynaptic dendrites. These neurons are cytologically identifiable by their small size, scant cytoplasm, characteristic chromatin clumps in nuclei that are not indented, and by having extended contacts with the cytologically different relay cells. We conclude that these neurons were not retrogradely labeled because of their intrinsic nature in LGN and, because of their common contacts with relay cells, we term them "satellite interneurons".

Animals↗
PubMed1980

Massive splenomegaly in Northern Zambia. II. Schistosomal splenomegaly and elevated IgG.

Twenty-three patients from Northern Zambia with massive splenomegaly due to chronic schistosomiasis were studied. The mean serum IgG levels were found to be extremely high compared with local blood donors and local patients with Tropical Splenomegaly Syndrome (TSS). Mean serum IgG levels also appear to be higher in Zambians with schistosomal splenomegaly than in those reported in patients from most other areas. Mean IgM levels of patients with schistosomal splenomegaly were higher than those of local blood donors, but not as high as in the TSS. IgG and IgM estimations are sometimes of value in the differential diagnosis of splenomegaly in the tropics.

Adolescent↗
PubMed1979

Morphogenesis of the fetal membranes of an American mole, Scalopus aquaticus.

Scalopus membranes are characterized by: Superficial nidation; antimesometrial orientation of the embryonic disc; amniogenesis by folding; an extensive but transitory choriovitelline placenta; a large yolk sac with late and incomplete inversion; large persistent allantoic vesicle; a very broad, thin, villous, epitheliochorial chorioallantoic placenta of annular shape interrupted mesometrially, dotted with numerous areolae, and bordered by a nonvillous sparsely vascular chorioallantoic membrane connected with the persistent bilaminar omphalopleure by a very narrow rim of chorion. There is no decidua. Electron microscopy shows that at 8 mm, CR, (limb bud embryo) the uterine epithelium of the interhemal membrane may be 0.5 micron or less in thickness, but that it shows no signs of degeneration. Trophoblastic microvilli often penetrate the epithelium to within 0.2 micron of its base. At this time there is active secretion by the uterine glands, and cellular hypertrophy and cytolysis of the epithelium at the gland mouths, with active phagocytosis by the areolar cytotrophoblast. The occurrence of absorptive areolae in an insectivore emphasizes the probable primitiveness of this widely distributed placental mechanism. In spite of similarities of the yolk sac to that of rabbits and rodents, the bilaminar omphalopleure produces no invasive trophoblastic giant cells. The definitive membranes of Parascalops breweri and Scapanus latimanus are like those of Scalopus. The placentae of Talpa europaea, Condylura cristata, and Neurotrichus gibbsii are discoid and relatively much smaller, thicker and more complex in internal structure. There is some reason to believe that the fetal membrane systems of moles and shrews (Soricoidea) are more like those of the ancestral mammalian stock than are those of any other recent eutherians.

Animals↗
PubMed1978

Red cell survival after aortic valve replacement with Björk-Shiley prosthesis in presence of sickle-cell trait.

A case of aortic valve replacement with a Björk-Shiley disc prosthesis in a patient with sickle-cell trait is presented. Six months after operation red cell survival was not significantly reduced. On theoretical and clinical grounds it is concluded that the presence of sickle-cell trait does not contribute to late postoperative haemolysis after heart valve replacement.

Anemia, Sickle Cell↗
PubMed1974

Studies with the high voltage electron microscope of normal, degenerating, and Golgi impregnated neuronal processes.

Synaptic relationships between neuronal processes have been studied in thick sections (up to 1.0 mum) with high voltage electron microscopy. Some of the problems that arise in the study of such thick sections have been considered. (1) Where two parts of a single process are in continuity through a narrow stalk, as a dendritic stem and one of its spines, the continuity can generally not be seen if the stalk is included within the section or is crossed in the section by other processes. (2) Membranes that are viewed face-on cannot be seen in the thick sections and, therefore, processes belonging to two separate nerve cells may appear as though they are in cytoplasmic continuity. (3) Synaptic junctions that are viewed face-on cannot be seen in the thick sections, and junctions lying close to the same angle are also invisible; the relative number of invisible junctions depends upon a number of factors, including the section thickness and the size and contrast properties of the junctional specializations. Two methods of marking neuronal processes have been explored: (1) degenerating axons that are undergoing the dark degenerative change can be recognized readily within the thick sections. However, they stand out less clearly than in thin sections. (2) Neuronal processes that have been impregnated by an extra-rapid modification of the Golgi method can be easily traced in thick sections. It is possible to study some of the synaptic contacts made by these impregnated processes, especially if the processes have been only lightly impregnated or if the silver dichromate deposits are secondarily removed.

Animals↗