Edward W. Dempsey

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.

Fine-structure of the rat's intercolumnar tubercle and its adjacent ependyma and choroid plexus, with especial reference to the appearance of its sinusoidal vessels in experimental argyria

Abstract The intercolumnar tubercle, a midline structure derived from the ependyma of the third ventricle, belongs to the group of structures in the central nervous system which stain intravitally with colloidal dyes and with silver nitrate. Silver is deposited in the basement membranes surrounding the vascular endothelium and especially in the reflection of the pia which partially surrounds the sinusoidal capillary vessels of the structure. Between these basement membranes a perivascular space exists, in which there are collagen fibers, fibroblasts and nerve terminations. Nerve cells, interspersed in the neuropil and often indenting the ependyma, have dendritic processes which penetrate into and between the ependymal cells to end near the cerebrospinal fluid space (third ventricle). Axons from these cells penetrate into the neuropil and end near the sinusoidal vessels and in their perivascular sheaths. These endings contain clear vesicles and dense granules of varying sizes. The morphological similarities between the intercolumnar tubercle, the pineal body and the neurohypophysis suggest that all are structures of neuroendocrine function. The relation of the cell bodies to the ependyma and ventricular space suggests further that the structure may have a function related to the composition of the cerebrospinal fluid.

The effect of angiographic contrast media at the cellular level in the brain.

Repeated carotid artery injections of contrast media were performed in cats and cerebral biopsy samples obtained for electron microscopy. Evidence suggests that there are two methods by which the blood-brain barrier may break down with repeated angiography: (a) alteration of the tight junctions between capillary endothelial cells in the brain, allowing passage of matter through these junctions, and (b) transport across the endothelial cells by pinocytosis.

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.

A unique form of endoplasmic reticulum in endocardial endothelia of the desert iguana

A unique and elaborate network of endoplasmic reticulum has been found in the endocardial endothelia of the desert iguana. The organelle consists of branched and anastomosed tubules which lack ribosomal particles. The tubules vary greatly in size and may be divided categorically into two groups of primary and secondary tubules, with average diameters of 750 A and 250 A, respectively. The tubular system appears to be arranged in a regular pattern. In some planes of section, most of the secondary tubules are seen to twist around one another in ropelike formations. In other planes of section, groups of one primary and two secondary tubules cut at different angles are arranged in definite rows. The most orderly configuration is observed in the endothelial cells resting upon noncontractile regions and appears distorted upon contraction of the underlying myocardia. In all circumstances, the amount of endoplasmic reticulum is unusual for endothelial cells because it occupies their entire cytoplasm. The tubules and membraneous surface of the endoplasmic reticulum are so abundant as to suggest some special physiological or biological activity although the true function of this interesting organelle is unknown.

The association of endoplasmic reticulum and mitochondria in placental cells.

Summary A characteristic complex of mitochondria and endoplasmic reticulum occurs in the yolk sac epithelium of carnivores and guinea pigs, and in the cytotrophoblastic cells of Langhans in the human placenta. In this complex, ribosomes are located predominantly on the cisternal membrane facing the mitochondrion. The significance of this complex is discussed briefly with respect both to protein synthesis and to fetal physiology.

Scanning Electron Microscopy of Glucocorticoid-Treated Hepatocytes and Hepatoma Cells in Culture:

Summary 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. This work was supported in part by United States Public Health Service Grants GM-15289, HD-05506, AM-05397, and CA-12536, and by the Perkin Memorial Fund of The Presbyterian Hospital in the City of New York. J.N.L. is the recipient of an Irma T. Hirschl Career Scientist Award.