Three large dissectable rat glomerular models reconstructed from wide‐field electron micrographs

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Abstract
Three very large styrofoam models of glomerular capillary tufts have been built, based on serial ultrathin sections which cut through three complete rat glomeruli isolated from all regions of renal cortex. The images of glomeruli are enlarged on 20" × 24" wide‐field electron micrographs, from which each capillary is traced on styrofoam discs and then individually connected. These models can be disassembled to measure the width and length of each capillary segment and to map the complicated glomerular vascular arrangement. Each of the three randomly selected glomeruli has three arteriolar openings passing through the Bowman's capsule–‐e.g., an afferent opening and two closely situated efferent openings. Each of the three glomeruli consists of three major lobules, e.g., two larger lateral lobules and a smaller central lobule. Assuming the model is positioned so that the vascular pole is superior and the afferent arteriole is closer to the observer than the two efferent vessels, the lobule occupying the frontal right portion originates from the right major branching of the afferent arteriole and reconverges at the right efferent opening. The lobule occupying the frontal left portion originates from the left major branching of the afferent arteriole and reconverges at the left efferent opening. The lobule occupying the central portion originates from the central major branching and connects both lateral lobules with a few interlobular anastomoses. The diameter and the length of interlobular anastomoses, and the volume of major lobules are listed. The technique of the isolation and reembedment of glomeruli and the construction of models is described in detail.