PubMed Health⌕ Search

Biomedical subjects

R Vagnerová

Publications and source records attributed to R Vagnerová.

4 recordsLinked to original sources
PubMed1997

Correlation of function and structure in developing rat distal colon.

The distal colon of suckling (14-day-old) and weanling (27-day-old) rats absorbs Na+ via channel-mediated, electrogenic amiloride-sensitive Na+ transport which disappears after weaning. This transport pathway is induced by aldosterone in superficial cells of colonic epithelium. The purpose of the present study was to correlate the changes in distal colon function with changes in the apical and basolateral cell membrane surface areas of superficial enterocytes. The basolateral but not apical membrane surface density (i.e. surface areas of the basolateral and apical membranes of superficial enterocytes per unit volume of superficial enterocytes) was found to increase between postnatal day 14 and 27 (i.e. during the weaning period). The plasma concentrations of aldosterone were very high during this period and electrogenic amiloride-sensitive Na+ transport and Na, K-ATPase activity were increased significantly. High dietary salt intake during the weaning period prevented the developmental increase of basolateral membrane surface density, inhibited electrogenic amiloride-sensitive Na+ transport and significantly depressed plasma aldosterone levels and Na, K-ATPase activity. Apical cell membrane surface density did not change significantly after a sodium load. Thus, high plasma concentrations of aldosterone and/or high colonic Na+ transport during weaning exert an important and selective effect on the basolateral membrane and are responsible for the developmental changes of this cell membrane surface during weaning. Concomitant changes in the morphology of superficial colonic enterocytes and in colonic Na+ transport suggest that the structure of the immature epithelium is related to its function.

Animals↗
PubMed1989

Note on differentiation of the epithelium of the small intestine in human embryos.

We studied the development of the human embryonic intestine from the 6th to the 8th week of gestation (embryos with a crown-rump length of 16-25 mm). Semithin sections show that a smooth, simple intestinal lumen, which is often a mere slit, is elsewhere, in the same specimen, distinctly formed and in places is partly occluded by accumulations of cells of a somewhat different character from those of the actual intestinal lining. Whereas the epithelium proper is mainly high and pseudostratified, the cells which secondarily occlude the originally open intestinal lumen are smaller and are more cuboidal to polyhedric in shape. In the electron microscope, the cells of the primitive epithelium appear narrow and columnar, with an ovoid nucleus and a few nucleoli. The cytoplasm contains numerous mitochondria and a gradually developing granular endoplasmic reticulum and Golgi complex. These cells have small, irregular microvilli on their surface, but some have an almost straight surface without any microvilli. They display striking pinocytotic activity and contain a quantity of multivesicular bodies. Their cytoplasm further contains isolated osmiophilic granules and lysosomes and a small amount of glycogen. The accumulation of glycogen is typical of the more mature developmental stages. Cilia are a characteristic finding in embryos with a c-r length of 16-25 mm. There is only one cilium to a cell, but not all the cells have cilia. The cilia are relatively thick and not very long and they almost always grow in the centre of the cell surface. The apical surface of such cells is usually slightly or more deeply concave. Structurally, the ciliated cells closely resemble phylogenetically primitive entodermal collar cells (choanocytes). They are apparently a phylogenetically old type of cells, whose existence could have functional value, which appears for a time during ontogenetic development. The cilia may temporarily play a role in the movement of the intestinal fluid and thus coparticipate in resorption before the musculature of the intestinal wall has been formed.

Cell Differentiation↗