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The three-dimensional world of the spleen was explored by scanning electron microscopy on both arterially perfused and nonperfused specimens, as well as on plastic corrosion casts of splenic vasculatures. Of 25 spleens studied, 18 were examples of hypersplenism. These were contrasted to 7 essentially normal spleens taken from children being staged for treatment of Hodgkin's disease whose spleens proved to be uninvolved in the pathologic process. Splenic sinuses in all 25 spleens were typified by a degree of porosity. RBC were caught in the act of entering sinuses from splenic cords. These sinus windows thus represent one end of an "open" circulation pathway. In casts of microvasculature, direct arteriovenous connections were demonstrated, thus establishing an anatomical basis for an often disputed "closed" circulation pathway. Spleens from 7 patients with hereditary spherocytosis had a super abundance of red pulp. Splenic cords were thickened and crowded with spherocytes, many of which presented slightly wrinkled membranes, as were also noted on the peripheral blood RBC. It is possible that these membrane features are unique for HS and reflect the intrinsic membrane abnormality in protein composition. The 7 spleens from chronic idiopathic thrombocytopenic purpura had white pulp as the predominant region. Germinal centers were frequent. Lymphocytes and plasma cells with well-developed microvilli were suggestive that release of antiplatelet antibody might be occurring in white pulp. Platelets were especially notable in peripheral white pulp and marginal zones. Platelet clumps were observed, generally adjacent to spleenic macrophages.

A nine-year-old black girl with essential thrombocythemia developed hemoptysis. Only two other cases in the English literature have been described. Ultrastructure and functional characteristics of this patient's platelets were studied. Twenty-six percent of the patient's platelets were very large (megathrombocytes). Spontaneous aggregated from the patient's platelets were not compact, and the pseudopods did not interdigitate. Both qualitative and quantitative defects in platelet organelles were detected. The microtubular system was faulty in organization. Furthermore, the number of granules (especially alpha granules) was reduced. Platelet aggregation studies demonstrated subnormal aggregation in response to ADP, epinephrine, and collagen, but aggregation with ristocetin was normal. It is postulated that a platelet membrane abnormality may be the cause of their defective platelet aggregation.

Scanning and transmission electron microscopy were used for a study of the surface and glandular ultrastructure of human endometrium in the presence of different types of IUDs at comparable phases of the menstrual cycle. The aim of the study was to compare the effect of the nonmedicated with the copper and multiload copper devices to further explain the differences in their contraceptive potencies and their mechanism of action. The endometrium was evaluated at and away from the IUD; emphasis was put on the ultrastructure of endometrial gland openings, secretory activity, cellular glycogen content, ciliated cells, microvillous pattern, and kinocilia. The changes of the surface ultrastructure of the endometrium in the presence of copper IUDs were more extensive in this study than those previously reported. There seems to be a direct relationship between the amount of copper incorporated in the device, the degree of ultrastructure changes, and the area of endometrium involved. Copper devices affect the endometrial cells away from the IUD. The altered secretory function with disturbed macroapocrine secretion, the abnormality of ciliated cells, and the defective microvillous growth seem to interfere with the physiologic and functional integrity of the endometrium, reducing the chances of contraception in the presence of copper IUDs.

The mission of this study was to determine whether or not arteriovenous connections, indicative of a "closed" type of circulation, existed in the human spleen. Spleens from four patients requiring therapeutic splenectomy were the basis for this report. Scanning electron microscopy of plastic corrosion casts, prepared from these four spleens, revealed direct vascular conduits between splenic pulp arteries or arterial capillaries and the venous sinuses in the red pulp. Also demonstrated were a few arteriovenous shunts between pulp arteries or arterial capillaries and pulp or trabecular veins. Inclusion of sized microspheres in low-viscosity perfusion plastic illustrated that some diameters of the connecting shunts were 7-10 mum, with other shunts even smaller. Not only do arteriovenous connections exist in human spleens, but their frequency, as revealed by methods accentuating three-dimensional aspects of the splenic microcirculation, justify future reconsiderations of the functional significance of this closed type of circulation. Examination of samples of the same intact spleens, prepared by freeze-fracture and conventional critical-point drying, also revealed an "open" type circulation structure, namely, pore-patterned sinus walls that could facilitate blood cell movement from pulp cords into venous sinuses. Scanning electron microscopy thus has provided direct evidence that human spleens have both "open" and "closed" circulatory pathways in their microvasculature.

Optical and electron microscopic evidence is presented to support the finding that sickling of hemoglobin S can be reversed and blocked by urea in invert sugar (UIS). Erythrocytes from subjects having hemoglobin SS, AS or AA were treated with the UIS either before or after deoxygenation with Na(2)S(2)O(5). Light microscopic studies indicated that approximately one-fifth as much urea is required to block sickling as is necessary to reverse sickled poikilocytes to normal forms. Intracellular microfilaments apparent in transmission electron micrographs of sickled erythrocytes were eliminated by treating aliquots of the same deoxygenated erythrocytes with UIS. Scanning electron micrographs showed a reversion of sickled poikilocytes to a normal erythrocyte population of biconcave discs. The use of UIS was deduced from Murayama's hypothesis that the molecular mechanism of sickling clearly involves hydrophobic bonds formed between the number-6 valine substitution of the beta-chain S globins and the alpha-chain globins of interacting hemoglobin molecules. The use of UIS to arrest the formation of such hydrophobic bonds is advocated as an evident and effective therapeutic strategy to treat sickle cell crisis.

A 17 yr old female with a congenital bleeding disorder was found to suffer from dysfibrinogenemia. Whole blood and plasma coagulation times were delayed and thrombelastograms were grossly abnormal. Clottability of plasma fibrinogen by addition of thrombin was not demonstrated during the 30 min test period. Fibrinogen was revealed by turbidometric and immunologic techniques. Other coagulation factors were present in normal amounts and prothrombin activation was normal. Patient's plasma inhibited thrombin clotting times of normal plasma and purified normal fibrinogen. Fibrinolysis was not detected. The plasma fibrinogen migrated normally on paper and cellulose acetate electrophoresis, but on immunoelectrophoresis it displayed a faster mobility than normal fibrinogen. On immunodiffusion the antigenic determinants were similar to those of normal fibrinogen. The patient's fibrinogen-antifibrinogen precipitins required longer to appear and the resultant precipitin was broader and hazier than those elicited with normal fibrinogen. These findings suggest the presence of two discrete populations of fibrinogen molecules. Investigation of the family of the patient suggested that the defect has an autosomal dominant pattern of heredity. Immunologic comparisons of our patient's plasma and of her relatives with plasma of patients with "Fibrinogen Baltimore" and "Fibrinogen Cleveland" revealed certain differences in immunoelectrophoretic mobility as well as in immunodiffusion. In keeping with the nomenclatures of abnormal fibrinogens in the literature, we propose the term "Fibrinogen Detroit" for this fibrinogen.Physicochemical properties of "Fibrinogen Detroit" were investigated also and compared with those of normal fibrinogen. Purified normal fibrinogen (clottability 96.7%) and "Fibrinogen Detroit" revealed homogeneity when studied by ultracentrifugation and immunoelectrophoresis. Native and cleaved "Fibrinogen Detroit" had the same sedimentation constants and molecular weights as the normal. In fresh samples. 3 moles of free SH groups/mole of fibrinogen were titrated in both. Determination of the amino acid composition revealed a decreased content of lysine, glucosamine, and galactosamine in abnormal fibrinogen. Total carbohydrates, protein-bound hexoses, sialic acid, and hexosamine were decreased in the abnormal fibrinogen. In an investigation with Doctors Blombäck a specific molecular defect was revealed in the N-terminal disulfide knot of the alpha (A) chain in which the arginine at the 19th position was replaced by serine. It is believed that the substitution of a strongly basic amino acid with a neutral hydroxy acid may result in considerable conformational changes in the N-terminal disulfide knot of fibrinogen which might affect the "active site" for polymerization. The lower carbohydrate content observed in "Fibrinogen Detroit" may have been the result of a change in primary and tertiary structure of the protein.