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T F Freddo

Publications and source records attributed to T F Freddo.

47 records · Page 3Linked to original sources
PubMed1984

Influence of mercurial sulfhydryl agents on aqueous outflow pathways in enucleated eyes.

Enucleated calf and primate eyes were perfused with either p-chloromercuribenzene sulfonate (PCMBS) or p-chloromercuribenzene (PCMB). Both caused a decrease in aqueous outflow that did not result from inhibition of glycolysis in trabecular cells. Morphologic studies of PCMBS-treated primate eyes suggested that the reduction in aqueous outflow occurred as the result of cellular swelling in the trabecular meshwork and, particularly, in the juxtacanalicular connective tissue. These findings suggest that changes in cell volume may influence trabecular outflow resistance and that mercurial-sensitive membrane sulfhydryl groups could participate in the regulation of aqueous outflow.

4-Chloromercuribenzenesulfonate↗
PubMed1984

Intercellular junctions of the iris epithelia in Macaca mulatta.

The intercellular junctions in the anterior myoepithelium and posterior pigmented epithelium of the rhesus monkey iris were examined using an ultrastructural tracer, conventional electron microscopy, and the freeze-fracture technique. Within the anterior myoepithelium the lateral cell margins were joined by puncta adhaerentia, desmosomes, and gap junctions. The distribution of the puncta adhaerentia and desmosomes was restricted to the apico-lateral region of these cells. Joining the apical surface of the anterior myoepithelium and posterior pigmented epithelium gap junctions, puncta adhaerentia, and desmosomes also were present. Adjacent posterior pigmented epithelial cells were joined by an apico-lateral junctional complex, which consisted of a zonula occludens, zonula adhaerens, and gap junction. These cells also were connected by one or more desmosomes. Intravenously injected horseradish peroxidase, which diffused from the ciliary body stroma, was prevented from reaching the posterior chamber by the presence of the zonulae occludentes between adjacent posterior pigmented epithelial cells. Their presence was confirmed using the double replica method of freeze-fracturing. The zonulae occludentes appeared as a continuous series of branching and anastomosing strands of particles on the P-fracture face, which were complemented on the E-fracture face by a series of shallow grooves. These junctions varied in complexity from one to eight or more strands indicating that they are analogous in both location and degree of permeability to the zonulae occludentes present in the nonpigmented ciliary epithelium.

Animals↗
PubMed1982

The homogeneous structure of blood vessels in the vascular tree of Macaca mulatta iris.

This study reports the results of a systematic analysis of the iris vasculature in Macaca mulatta. Through the application of a variety of morphologic procedures it has been demonstrated that in rhesus monkeys, all iridial vessels, regardless of their diameter, have a similar structure. Their walls consist of (1) endothelial cells in a continuous layer resting on a basal lamina, which are provided with a small number of blunt luminal protrusions and slender basal lamellae; (2) pericytes sandwiched between two layers of the basal lamina, which are characterized by a smooth basal surface and adluminal processes that interdigitate with the basal leaflets of the endothelial cells; and (3) an adventitia of fibroblasts, melanocytes, and occasional macrophages arranged in one or more layers. Typical smooth muscle cells are not found in any vessels of M. mulatta iris. Thus the vessels of the rhesus monkey iris have a remarkably homogeneous morphologic appearance and cannot be classified according to the traditional criteria for arterioles, capillaries, and venules.

Animals↗
PubMed1982

Freeze-fracture analysis of the interendothelial junctions in the blood vessels of the iris in Macaca mulatta.

The interendothelial cell junctions in the blood vessels of the rhesus monkey iris were examined by both conventional electron microscopy and the freeze-fracturing technique. Endothelial cells of iris blood vessels were joined by two types of intercellular junctions: zonular tight junctions and gap junctions. The zonulae occludentes were represented by a complex network of branching and anastomosing strands that remained preferentially associated with the E fracture face. They varied in complexity from a single strand to eight or more but usually consisted of from two to four strands. Small gap junctions were inserted within the tight junctional network. Junctions similar to those typical of muscular and visceral venules were absent. Thus the intercellular clefts of all iris vessels are closed by zonulae occludentes that exhibit a degree of complexity intermediate between the endothelial junctions of the cerebral cortex and those of striated muscles and viscera. This finding strongly suggests that the blood vessels of the iris participate only minimally in aqueous humor dynamics.

Animals↗
PubMed1980

Rod-shaped bodies and crystalloid inclusions in ocular vascular endothelia of adult and developing Macaca mulatta.

In addition to the usual organelles, endothelial cells of ocular blood vessels and Schlemm's canal in adult and fetal Macaca mulatta, contain two types of inclusions: rod-shaped bodies and crystalloids. The rod-shaped bodies are similar to those first described in arterial endothelia of the rat. They are between 0.2 to 0.35 micrometer in diameter, up to 2.5 micrometers in length, and are membrane bounded. The crystalloid inclusions are up to 1.2 micrometers in diameter and are associated with the granular endoplasmic reticulum. Their crystalline lattice consists of subunits, 28 nm in diameter, which are either arranged in rows separated by amorphous matrix or tightly packed in a honeycomb-like lattice. The rod-shaped bodies are much more numerous than the crystalloids; however, both kinds of inclusions are consistently found in both adult and fetal vessels. The represent normal components of ocular vascular endothelia which appear very early in the development of the eye.

Animals↗
PubMed1980

A simple staining method for blood vessels in flat preparations of ocular tissues.

We describe a technique for light microscopic visualization of the vasculature of the retina, choroid, ciliary body, and iris in flat preparations. The technique is based on the intravenous injection of horseradish peroxidase, the histochemical demonstration of this enzyme's activity, and the bleaching of the melanin that hinders the visualization of the injected vessels. This technique is reproducible and much simpler than other available methods in which dyes suspended in different media are injected directly into the ocular vessels.

Animals↗
PubMed1976

Future of optometric education: a student view.

With the growth of optometry and the advent of a national health insurance plan, the practice of optometry will change. As it does, so too must optometric education. This paper outlines a student's views on how admissions, curricula, new schools, and board certification must change if optometry is to fill a primary health care role.

Certification↗
PubMed1976

An assessment of the generation times of neuronal precursors in the sensory retina and subventricular zone of the newborn rat.

Generation times and the times for their respective phases were determined for neuronal precursors in the sensory retina and subventricular zone of the brain of newborn CD rats. These regions can be induced to form retinoblastoma and medulloepitheliomas, respectively, following injection of adenovirus-12. Through use of autoradiographic techniques, it was shown that the cell cycle duration in the subventricular zone was almost twice as long as in the sensory retinal layer. The G1 phase durations were found to account for the majority of the time difference.

Adenoviridae↗
PubMedDate not supplied

Differences in nuclear pore density among human choroidal melanoma cell types.

Two cases of mixed cell type choroidal melanoma were examined by means of conventional and freeze-fracture electron microscopy. Data on average nuclear pore density were readily collected from freeze-fracture replicas of spindle A, spindle B, and epithelioid cells. Highly significant (p less than 0.001) differences in pore densities were found among the three cell types. Pore density was lowest in spindle A cells, intermediate in spindle B cells, and highest in epithelioid cells. The possible relationship between nuclear pore density and nucleolar activity as well as the potential usefulness of this new finding as a prognostic indicator in cases of choroidal melanoma are discussed.

Cell Nucleolus↗