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The fine structure of the rod-bipolar synapse is described and illustrated. Each rod spherule possesses a large, single, oval or elongate mitochondrion approximately 0.5 X 2.0 microns. Surrounding the mitochondrion are elements of agranular endoplasmic reticulum. The bipolar dendrite projects into the lower pole of the spherule and usually terminates in two lobes separated by a cleft. The plasma membranes appear dense and thicker in the region of the synapse. In the rod spherule cytoplasm, contiguous with the plasma membrane is a dense, slightly concave arciform structure, the rod ardform density, extending from the base of the bipolar bifid process through the cleft to an equivalent point on the opposite side. Also within the spherule, and external (towards the sclera) to the rod arciform density, is a parallel, dense, thin lamella, the rod synaptic lamdla. This is approximately 25 m# in thickness and 400 m# in width at its widest extent. This halfmoon-shaped plate straddles the cleft between the two lobes of the bipolar process. The lamella appears to consist of short regular rodlets or cylinders 5 to 7 m# in diameter, oriented with their long axes perpendicular to the plane of the lamella. Minute cytoplasmic vesicles found in the cytoplasm of both the rod spherule and the bipolar terminal are most abundant near the rod synaptic lamella.

Endobronchial lavage was performed on eight smokers and eight nonsmokers. Centrifugation of lavage fluid produces a sediment consisting of two layers, a lower compact brown layer containing cells and a n upper flocculent white layer. The brown layers from the smokers were greater in volume than those from the nonsmokers. Macrophages constituted about 93% of the cells from the smokers and about 63% of the cells from the nonsmokers. These data suggest that more free macrophages occur in the lungs of smokers than nonsmokers. In addition, many of the macrophages obtained from the smokers were filled with cytoplasmic inclusions. The volumes of white layers from the smokers were smaller than those from the nonsmokers. One white layer obtained from a nonsmoker was examined in a Wilhelmy balance and proved to be surface-active. This may suggest that surface-active material, pulmonary surfactant, is reduced in lavage fluids from smokers.

The ductnii efferentes and rete testis of the guinea pig were isolated by micro dissection, fixed in cold buffered osmium tetroxide, and sectioned for examination with the light and electron microscopes.Proximal and distal segments of the duetnii efferentes were identified and their respective cytological organizations characterized. The cytological components of the rete testis are briefly described and figured.Non-ciliated and dliated ceils are found in both segments of the ductuli efferentes. The non-cillated cells have a microvilious border, mitochondria, a Golgi complex, an ubiquitous endoplasmic reticulum, and numerous cytoplasmic vacuoles. The ciliated ceils contain more mitochondria, an endoplasmic reticulum with a relatively sparse distribution, and few, if any, cytoplasmic vacuoles. A regional difference exists in proximal and distal segments based on the distribution, size, number, and eleetron opacity of the cytoplasmic vacuoles. Attention was paid to the disposition of the endoplasmic reticulum and its relation to the system of cytoplasmic vacuoles. These findings are interpreted as suggesting that the continuity of the vacuolar system with elements of the endoplasmic reticulum represents a pathway for transfer of large quantities of fluid, an activity which has long been ascribed to the epithelium of the ductuli efferentes.Periductular capillaries possess pore-like apertures in their endothelia similar to those in other tissues known to engage in fluid transfer.The capacity for reabsorption by the epithelial cells of the ductuli efferentes was first postulated by yon Mifllendorff (1920Mifllendorff ( , 1922. He found that these cells store subcutaneously injected vital dyes such