Quantitative variations in the disposition of the enteric surface coat in mouse jejunum

Biological and pathobiological aspects of the glycocalyx of the small intestinal epithelium. A review

The literature on the glycocalyx of small intestinal epithelium is reviewed. The structure, general and barrier functions, synthesis, and degradation of the glycocalyx, and pathobiological aspects of the glycocalyx in relation to its barrier function are mentioned. Topics for future research are indicated.

Transport across endodermal cells of the chick yolk sac during early stages of development

The endoderm of the chick yolk sac mediates the transfer of materials from the yolk mass to the embryonic circulation. There is little evidence of endocytotic activity in the area pellucida, but the endodermal cells of the area vasculosa possess many microvilli and bristle-coated pits and vesicles, as well as a canalicular system and vacuoles in the apical cytoplasm. Three tracers, horseradish peroxidase, ferritin, and latex spheres, were injected beneath the endoderm of both cultured embryos and embryos in ovo to study the pathway of uptake of extracellular materials. All tracers were sequestered in bristle-coated pits (200-500 nm in diameter) of the endodermal cells of the area vasculosa, but not those in the area pellucida. Both horseradish peroxidase and latex spheres (and probably ferritin) were incorporated into pleomorphic intracellular yolk drops through bristle-coated pits and vesicles, and then into apical vacuoles, which fuse with the intracellular yolk drops. Horseradish peroxidase and ferritin were also found within apical canaliculi. The apical junctions between endodermal cells prevented the intercellular passage of the tracers. A "topping-up" hypothesis is opposed whereby endodermal cells of the area vasculosa continually sequester extracellular yolk material, which is incorporated into a digesting intracellular yolk drop while, at the same time, digested yolk products are being transported across the vascular pole of the endoderm to the extraembryonic circulation and thence to the embryo.

The delayed effects of ethacrynic acid on the stria vascularis of the guinea pig

Guinea pigs were administered 40 mg ethacrynic acid per kg b.wt. and sacrificed at 30-48 minutes, 3-4 hours, 2 or 7 days post-drug. Cochlear potentials (EP and CP) were monitored before sacrifice. At 30-48 minutes, the potentials had decreased considerably, and a marked edema plus cytological changes were visible in the stria vascularis. The potentials had recovered to about 75% of their original value at 3-4 hours; some cell recovery was visible, but the edema was still present. Potentials recorded from the basal turn were normal at 2 and 7 days, although some strial cells showed deterioration.

Demonstration of the fuzzy surface coat of rat intestinal microvilli by freeze-etching

In freeze-etch replicas of epithelial cells of rat rectum, the fuzzy surface coat is composed of discrete filaments which are aligned in parallel with each other and with the long axes of the microvilli.

Microblebs of intestinal epithelial cell microvilli of Citellus tridecemlineatus

The presence of microblebs arising from the lateral surfaces and tips of microvilli of intestinal epithelial cells of thirteen-lined ground squirrels. Citellus tridecemlineatus, is reported. Microblebs measure approximately 50 nm in diameter and are bounded by a unit membrane which is continuous with the unit plasma membrane of the microvilli. It is suggested that such microblebbing reflects the rapid turnover of microvillar contents, membrane and surface coat.