Microcirculation of the rat placenta. Scanning and transmission electron microscopic observations on fetal blood vessels.

The fetal circulation of normal rat placenta was studied by parallel examination with the scanning electron microscope (SEM) and the transmission electron microscope (TEM). By examining casts of vessels injected with latex and prepared by corrosion in hypochlorite solutions, the fetal arteries, veins, and capillaries of the placenta could be traced in the scanning electron microscope and, in addition, the ultrastructural details of microcirculation and luminal surfaces could be studied. Cast specimens showed fetal arteries entering the center of the placenta and branching into long, thin vessels which traversed almost the entire thickness of the placenta before dividing into a markedly tortuous capillary network. The smooth-surfaced capillary vessels located at the arteriolar end flowed into a much less tortuous prevenous capillary network which conducted the blood into collecting venules and veins. Placental blood vessels examined by the TEM provided evidence that details observed by the SEM were accurate for the ultrastructural appearance of fetal arteries, capillaries, and veins.

Scanning electron microscopy of glucocrticoid-treated hepatocytes and hepatoma cells in culture.

The morphological effects of exposure to hydrocortisone have been examined in two cell lines of liver origin by scanning electon microscopy. In one of these, an aneuploid line derived from a Morris hepatoma, the presence of hormone results not only in a suppression of cell proliferation, but in a marked flattening of the cells and loss of surface microvilli; in the other cell line, a diploid line derived from adult rat liver, the suppression of cell division is less marked, and the morphological effects of the hormone are far less striking. While the suppression of cell division in both of these cell lines is known to be rapidly reversible upon the removal of hormone, the presence of hormone causes the hepatoma cells to assume both monolayer growth characteristics and a morphology resembling those of cells derived from normal liver.

Alterations at the cellular level in the brain following repeated angiography: protective effect of corticosteroids.

Repeated injections of angiographic contrast media disrupt the blood-brain barrier and lead to transient cerebral edema in the normal experimental animal brain. The corticosteroid, dexamethasone, protects against the development of this edema without altering the effect of the contrast media on the tight junctions between adjacent endothelial cells. Indirect evidence is presented to support the theory that the corticosteroids function to maintain the integrity of the endothelial cells.

Electron microscopy of the intestine of the African lungfish, Protopterus aethiopicus.

Electron microscopic observations are reported on the intestine of the African lungfish, Protopterus aethiopicus. The lungfish has a spiral valve rather than a true stomach. Segments of mucosa from this area reveal, by transmission microscopy, that most cells have distinct striated borders with parallel microvilli. Fibrils within the core of the microvilli extend deeply into the cytoplasm. Microvilli on the surface of goblet cells are less regularly arranged than those of absorptive cells. Interspersed among the cells with striated borders are cells, similar in cytologic appearance except that they are covered with tufts of kinetocilia. By transmission electron microscopy, abnormal cilia having one complete complement of microtubules plus incomplete sets from other cilia which share some of the peripheral doublets of the complete cilium are enclosed by a single membrane. Cilia are usual in the intestine of many lower forms but ordinarily absent in higher vertebrates. Their functional significance in this primitive fish is unknown.

Scanning electron microscopy of the human fallopian tube.

Fallopian tubes from women of reproductive and postmenopausal ages were examined by scanning electron microscopy. The surface topography of these Fallopian tubes is described and illustrated.