The spatial distribution and densities of photoreceptors in seven whole-mounted porcine retinas were studied and maps illustrating photoreceptor topography were constructed. Total photoreceptor densities ranged from to 83 000 to 200 000 cells/mm2, with a mean of 138 500 cells/mm2. Cone densities ranged from 39 000 (area centralis) to 8500 cones/mm2 (peripherally), with a mean of 16 400 cones/mm2. Rod:cone ratios ranged from 3:1 centrally to 16:1 peripherally, with a mean ratio of 8:1. Averaged photoreceptor densities are greatest (166 000 cells/mm2) within the central inferior retina, and regional differences in rod:cone ratios were found. Cone densities are increased in a broad region dorsal to the optic disk, extending both nasally and temporally. This region is believed to represent the area centralis. Cone densities gradually decrease and taper towards the periphery and inferior retina as rod:cone ratios increase. In addition to the many anatomic and ultrastructural similarities to the human eye, this study illustrates similarities within the photoreceptor mosaic of these two species and supports the use of the pig retina as a model for human/animal research.

The aim of this study was to investigate sodium hypochlorite (with and without EDTA), chlorhexidine, and hydrogen peroxide in varying concentrations when used in sequence or in combination as endodontic irrigants. Sterile saline served as the control. Six standardized bovine incisor root specimens, which had been infected with Enterococcus faecalis (CG 110), were exposed to each solution. Following exposure to the test agents dentine samples were taken from within the lumina using ISO 023 to 035 burs. The dentine powder samples were incubated and the quantity of bacteria present assessed using spectrophotometry. All irrigant regimens were more effective than saline in killing bacteria. Chlorhexidine and sodium hypochlorite were similarly effective. At specific concentrations a synergistic effect was noted when mixtures of chlorhexidine and hydrogen peroxide were under test.

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