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R Georgieva

Publications and source records attributed to R Georgieva.

49 records · Page 3Linked to original sources
PubMed1975

The morphological and functional differentiation of the alimentary canal of the pig during ontogeny. I. Development and differentiation of the fundic portion of the stomach.

Several periods of intensive growth are observed in the development of the fundus of pig's stomach: at the end of the 2nd and the beginning of the 3rd month of embryogenesis, the periods shortly prior to and after birth, and between the 10th and 20th day following birth. The gastric pits are formed at about the 45th day of embriogenesis. At the beginning of the third month the fundic glands are formed. The parietal cells first differentiate and are found in 60-day old embryos. The mucous neck cells are differentiated at the beginning of the 3rd month but secretion of mucoid substance starts on about the 45th to 50th day of the prenatal development. With increasing age of the pigs the quantity of PAS-positive substances in the surface epithelium, as well as in the mucous neck cells gradually increases. The differentiation of the chief cells rich in RNA occurs approximately on the 90th day of the prenatal development.

Age Factors↗
PubMed1975

The morphological and functional differentiation of the alimentary canal of the pig during ontogeny. II. Development and differentiation of the jejunum.

Morphological development and differentiation of the pig's jejunum during ontogenesis were studied. It was found that villi intestinalis are formed on about the 40th day of embryogenesis. The differentiation of absorptive epithelium, goblet cells and argentaffine cells as well as the formation of the Lieberkühn's crypts, and muscularis mucosae, occur by the end of the 2nd and at the beginning of the 3rd month of the prenatal development. The Paneth cells are found in the period around birth. After birth there is an adaptive rearrangement of the mucosa of jejunum affecting both the epithelium and the propria: the rearrangement is conditionally divided into two periods - from birth to the 3rd day, and from the 10th to the 20th day.

Age Factors↗
PubMedDate not supplied

Permeation of macromolecules into polyelectrolyte microcapsules.

Polyelectrolyte microcapsules (PEMCs) have been prepared by coating red blood cells with the polyelectrolytes poly(styrenesulfonate), poly(allylamine hydrochloride), and dextran sulfate applying the layer-by-layer technique with subsequent dissolution of the core. The capsule permeability for human serum albumin (HSA) was studied as a function of the ionic strength and pH by means of confocal microscopy. PEMCs produced with dextran sulfate and poly(allylamine hydrochloride) show a significant increase in permeability for HSA at salt concentrations over 1 mM. For PEMCs prepared with poly(styrenesulfonate) and poly(allylamine hydrochloride) the limiting salt concentration is 5 mM. No pH dependence for permeation was observed. A correlation between the permeation and adsorption of HSA on the PEMC walls was investigated. Finally, a mechanism for the permeability, combining electrostatic interactions, and the presence of pores in the polymer layers is presented confirmed by the considerable increase of permeation of charged molecules in the presence of salt and the permeation of neutral molecules regardless of the ionic strength.

Biopolymers↗