Arginine-vasopressin in anterior pituitary cells: in situ hybridization of mRNA and ultrastructural localization of immunoreactivity.

The hypothalamic nonapeptide arginine-vasopressin (AVP) exerts several distinct receptor-mediated actions on pituitary cells. Although hypothalamic AVP reaches the anterior pituitary via well-defined pathways, there is now accumulating evidence that AVP may also be produced endogenously in anterior pituitary cells. Using in situ hybridization, we demonstrate here the presence of AVP mRNA in the anterior pituitary of the rat.

Human immunodeficiency virus type 1 infection of U937 cells promotes cell differentiation and a new pathway of viral assembly.

The differentiation of U937 monoblastoid cells after human immunodeficiency virus type 1 (HIV-1) infection was studied using the following approaches: reverse transcriptase activity measurement, immunofluorescence labeling, and electron microscopy. For comparison, uninfected U937 cells were induced to differentiate from monocyte to macrophage by phorbol 12-myristate 13-acetate (PMA) or retinoic acid (RA) treatment. Both infected and drug-treated cells showed important and similar ultrastructural cell modifications, with a phenotype that decreased in monocyte specificity and increased in that of macrophages.

Outer root sheath cells of human hair follicle are able to regenerate a fully differentiated epidermis in vitro.

During wound healing, interfollicular epidermis can be regenerated from the outer root sheath of hair follicles, showing that the cells of this structure can shift toward an interfollicular epidermal phenotype. Similarly, it has been shown that a multilayered epithelium originating from outer sheath cells can be obtained in vitro by culturing hair follicles. However, in the culture systems developed so far, the phenotypical shift was incomplete since the cells retained some of their original characteristics and did not acquire several key markers of terminally differentiated epidermis.

Normal Merkel cells express a synaptophysin-like immunoreactivity.

Synaptophysin (SY), a specific component of the membrane of presynaptic vesicles, has been reported as a novel marker for neurons, certain neuroendocrine cells and their neoplasms including neuroendocrine carcinomas of the skin. The origin of the Merkel cells (MC) being far from clear, this study was performed to establish if normal MC express SY. It is demonstrated by immunofluorescence and immunoelectron microscopy using a monoclonal antibody SY38 to this glycoprotein that normal MC in man, rabbit and pigs express an SY-like reactivity.

Herpes gestationis factor reacts with the amniotic epithelial basement membrane.

Sera from five patients with clinically and immunopathologically proven herpes gestationis were studied by complement fixing immunofluorescence and complement fixing immuno-electron microscopy using specimens of skin, amniochorion and placenta. The results demonstrated that the complement fixation antibody (herpes gestationis factor) could bind to the basement membrane zone of skin, amnion and chorion laeve but not to that of the placental syncytiotrophoblast. These data suggest that the herpes gestationis factor may be induced by the basement membrane zone antigens of extra-villous cytotrophoblasts.

Ultrastructural aspects of skin after cryoultramicrotomy.

Skin was studied by transmission electron microscopy after cryoultramicrotomy. Global and ultrastructural preservation of the tissue was obtained with satisfactory cohesion between dermis and epidermis. The main constitutive elements could be observed with good definition allowing easy recognition of all the organelles and therefore absolute identification of each cellular type encountered.

Lamellar cells of sensory receptors and perineural cells of nerve endings of pig skin contain cytokeratins.

The lamellar cells of the sensory corpuscles of the pig dermis must be considered to be epithelial cells as they contain cytokeratins. The cytokeratins detected are similar to those found in simple epithelia. Moreover, lamellar cells are embedded in an extracellular matrix reminiscent of the basement membrane of epithelium since it contains laminin and collagen IV.

Identification of a 37 kilodalton protein at the epidermal basement membrane by an antiserum to human amnion.

A protein which is recognized by an antibody to human amniotic epithelial basement membrane was identified at the basal lamina of human epidermis by immunohistology. This protein was localized at the lamina lucida of human epidermal basement membrane by immunoelectron microscopy. Studies of normal human keratinocyte cultures and epidermal wound healing suggested that the protein was probably produced by keratinocytes.

High-yield purification of plasma membranes from transformed human keratinocytes in culture.

The density pertubation technique with cationic silica microbeads was applied to prepare highly purified plasma membranes from cultured human keratinocytes. Trypsinized cells were coated successively with the beads (diameter approximately 50 nm, gravity greater than 2 g/cm3) and polyacrylic acid before they were lysed by osmotic shock and mechanical shear. The plasma membranes remained in the form of large open sheets which could easily be separated from other cell organelles and the cytosol by low-speed centrifugation.

Scanning electromicroscopy of suction blister-roofs from psoriatic lesions and normal skin.

Suction blisters were raised on psoriatic lesions and normal appearing skin. The epidermis was separated at the epidermal-dermal junction. Scanning electronmicroscopy of the dermal side of the blister-roofs from normal looking skin and almost healed psoriatic lesions showed stellate cells probably formed by cytoplasmic extensions ending at desmosomes.

Familial rolled and spiral hairs with palmoplantar keratoderma.

A 59-year-old man with palmoplantar keratoderma and rolled spiral hairs on the abdomen and extremities is reported. His father had the same skin manifestations but his brother and sister only keratoderma palmoplantare. Scanning electron microscopy of the rolled hairs showed that they were coiled in a spiral around their own axis.

Actin containing filaments in sheep choroid plexus cells infected in vitro by Visna virus: an immunofluorescent and ultrastructural study.

The in vitro infection of sheep choroid plexus cells by Visna virus induces changes in the distribution and the orientation of actin containing filament bundles. During the cell fusion the stellate shape of cells with several interdigitations is associated with radial spanning of the contractile system. The intercellular contacts are characterized by the occurrence of a discontinuous line of rich actin containing dots which could be a junction of several short filament bundles.

[Ultrastructural aspects of sheep choroid plexus cells during exogenous cell fusion induced by Visna virus in vitro].

During the first moments of the in vitro infection of Sheep choroid plexus cells with high multiplicities of infection of Visna virus, the authors observed: a strong development of GERL, some signs of an intensive protein synthesis and numerous filament bundles. This infection leads to an exogenous cell fusion.

[Technic for the morphometric study of cells in culture, about the in vitro stimulation of ovarian stroma cells by H.C.G].

Sizes for ovarian stroma cells in culture are according to a log normal distribution. Cell stimulation by H.C.

[Evidence for the production of a fusion factor during in vitro infection of sheep choroid plexus cells by visna virus].

One of the most important early events during the infection of sheep choroïd plexus cells in culture by Visna virus is the synthesis by these cells of a fusion factor distinct from the virus. The cell fusion activity of this factor does not seem transmissible. It promotes cell shape changes and a migration of the nucleus towards the cell wall.

Inorganic cytoplasmic inclusions in alveolar macrophages. The role of cigarette smoking.

A case of tobacco-associated pulmonary fibrosis, with the results of histological, ultrastructural, and spectrometric analysis is reported. Abnormalities of the alveolar macrophages, which are particularly affected by tobacco inhalation were found. The size of the macrophages was increased and many large, polymorphous inclusions, including fat vacuoles and granular deposits, which were either homogeneous or electron lucent vacuoles, were seen in the cytoplasm.

[Kinetics and ultrastructure of sheep fibroblast fusion induced by polyethylene glycol. Comparison with endogenous cell fusion induced by Visna virus].

The authors compare the fusion of sheep fibroblasts induced by low multiplicities of infection using visna virus and by high concentrations of polyethylene-glycol. In the case of Visna virus cell fusion is of the endogenous type, while fusion induced by polyethylene-glycol is of the exogenous type. The ultrastructural features are discussed for each type of cell fusion.

[Bioligical aspects of cell fusion induced in vitro by sheep Visna virus].

Visna virus induced cell fusion of sheep choroid plexus cells was explored in vitro. Fusion is early rapid, and of exogenous origin for multiplicities of infection equal to or greater than 2 UFP per cell; whereas fusion is slow, late-occurring and of endogenous origin for multiplicities of infection less than or equal to 0.75 UFP per cell.

[Ultrastructural aspects of the cell fusion induced by Visna virus on sheep choroid plexus cell in culture].

Sheep choroid plexus cells infected with low multiplicities of infection of Visna Virus were stellate and had long and thin processes containing filaments and forming cytoplasmic bridges between adjacent cells. Enlargement of the bridges resulted in the formation of multinucleated cells. Some glycoproteins were clustered on filaments outside the cell.

[Electron microscopic observation of the infectious cycle of Visna virus in sheep choroid plexus cells at temperatures under 37 degrees C].

Electron microscope study of viral penetration at 4 degrees C shows that viral particles first attach to cells. The attachment sites are invaginations which later fuse to form phagocytic cytoplasmic vacuoles. Some virus particles with altered envelopes can be seen in the cytoplasm.