Rats underwent unilateral labyrinthectomies and were then subjected to free-fall tests. Videotaped recordings of the fall movements were analyzed for asymmetry and adaptation. Several methods of recording and analysis were tried. Analysis was found to be enhanced by the use of an automatic 3D computer analysis.

Phospholipase A(2) (PLA(2)) activity was found and measured in the cell-free supernatants of human mononuclear cells (monocytes and lymphocytes) cultured with platelets for 48 h at 37 degrees C. The relative molecular mass of purified, calcium-dependent PLA(2) was 14 kD. The amount of PLA(2) in the supernatants correlated positively with the number of monocytes and platelets in the cultures. Electron microscopically, direct cell-to-cell interactions of monocytes and platelets were observed. Cultivation of suspensions of human mononuclear cells with platelets in serum-free medium was found to be an efficient way to produce and purify human secretable PLA(2). In the release of secretable PLA(2) in peripheral blood, the interactions between platelets and monocytes may play a considerable role.

The phenomenon that the autologous human platelets can be phagocytosed in vitro by neutrophils and monocytes of healthy human donors (being free of antiplatelet autoantibodies) was demonstrated earlier. In this study we have confirmed electron microscopically the phenomenon of phagocytosis. Besides, using flow cytometric analysis, we have shown that a possible way for the bridge-formation between the washed platelets and neutrophils can be the linkage via IgG + C3b complexes bound to the Fc receptors of platelets. This mechanism supposedly may play a role also in the clearance of platelets by peripheral phagocytes in vivo.

The presence of virus in peripheral blood mononuclear cells of asymptomatic antibody positive haemophiliacs was detected by assaying for reverse transcriptase and confirmed by electron microscopy and immunofluorescence. HIV has been detected in 5 out of 7 individuals. In order to investigate strain variation, supernatant fluids of cultures were added to H9 and MT-4 cells. Virus was recovered in MT-4 cells in 3 cases, whereas the H9 cells only supported the replication of 2 strains. Viruses isolated from asymptomatic haemophiliacs have a narrower range of infectivity than HTLV-IIIB.

Amniotic fluid cells from 31 pregnancies with fetuses having open neural tube defects (NTDs) and from 43 pregnancies with fetuses free of NTDs were studied with the use of the immunoperoxidase method for alpha-fetoprotein (AFP) and glial fibrillary acidic protein (GFAP). The authors also used cytochemical stains for endogenous peroxidase and nonspecific esterase activity. In cases of NTDs, macrophages were present in the amniotic fluid, and in the authors' system they showed intense immunoreactivity for both AFP and GFAP and showed very strong activity for peroxidase and nonspecific esterase, whereas the epithelial cells and red blood cells showed no activity. In six cases of anencephaly, sections from the margin of the cranial end of defective spinal cords at the aperture of the open lesion were also studied for AFP and GFAP. In these cases, AFP- and GFAP-positive cells were found, indicating the possible neural (glial) origin of a part of amniotic fluid macrophages. Although the determination of AFP levels in maternal blood and amniotic fluid is widely used in the prenatal diagnosis of NTDs, demonstration of AFP in amniotic fluid cells by means of immunocytochemistry has not been described.

During storage, discocyte-echinocyte transformation of erythrocytes occurs progressively and microvesicles release from the spicules in the form of membrane-encapsulated red cell fragments. After rejuvenation part of the membrane-deficient cells, mainly spheroechinocytes, transform into spherostomatocytes because of their inability of restoring the surface area to volume ratios of normal discocytes. The proportion of spherostomatocytes formed on rejuvenation increases with storage time. Numerical indices for characterizing the "level of reversion" and the "quality of reversion" were developed. Osmotic fragility curves and light scattering histograms also reflected a partially irreversible increase of inhomogeneity of stored cell populations.

Blood collected with CPD and stored was examined with optical (LM) and scanning electron microscopy (SEM) before and after reversal of echinocytes into disco‐cytes. Reversal was achieved by incubation of the red blood cells at 37 C in an adenosine containing medium. The transformation of discocytes into echinocytes occurred rapidly during the first three weeks of storage. A shape/density relationship was observed in the various fractions. The denser cells were found to have the more advanced echinocytic changes. After incubation with adenosine, most of the cells reversed into discocytes and early stages of stomatocytes. When spheroechino‐cytes I and II were present, they reversed into sphero‐stomatocytes. No echinocytogenic property was found in plasma during 5 weeks of storage at 4 C and no immediate reversion of echinocytes was obtained in fresh plasma, therefore the initial discocyte‐echinocyte transformation was explained by intracellular changes. The data from the various fractions showed that the more dense cells were more spherocytic. We suggest that removal of this part of the population of stored red blood cells might improve the survival of transfused cells.

Histological changes caused by triiodothyronine (T3) and mercaptoiminazole treatment as well as by thyroidectomy have been studied in the proximal growth organ of the tibia of growing rats. On triiodothyronine treatment morphometric examinations revealed an increased proliferation and resorption of cartilage associated with a transitory acceleration of linear bone growth. Administration of mercaptoiminazole and thyroidectomy inhibited cartilage proliferation and resorption resulting in a slowing down of bone growth.

The 24 hour growth rate of the tibial proximal growth organ was investigated in triiodothyronine or mercaptoimidazole-treated, and in thyroidectomized male rats. Longitudinal growth of the tibia of the same period was also studied. After one week treatment, the 24 hour rate of growth in the triiodothyronine-treated rats was retarded as compared with the controls, whereas at the end of the 3rd and 5th weeks the growth rate of the treated animals exceeded that of the controls. The tibia was somewhat longer in the treated rats than in the untreated controls, though the difference was not significant. The growth rate in the growth organ of mercaptoimidazole-treated and thyroidectomized animals was generally higher than that measured in the controls. The length of the tibia was less than in the controls, but the difference was not significant. The phenomenon is attributed to the altered hormonal conditions.