[Biological function of vitamin A]

The paper deals with the generalized results of complex studies in the biological function of vitamin A conducted on the chicken glandular stomach. It is found out that at a certain diet the glandular stomach of chickens manifests a specific response to vitamin A deficiency: the amount of cells in the organ increases, their differentiation changes, the tissues relation is disturbed, hyperfunction is observed. The content of acid glycosaminglycanes varies, their biosynthesis is inhibited, the concentration of cations in the intercellular space increases. On the basis of these facts a conclusion is drawn that disturbances in the structure and function of glycocalyx are decisive in development of A-avitaminosis. It is established that the stomach intermediate zone mucosa secretion contains vitamin A which is strongly bound with a specific water-insoluble glycolipoprotein. The absence of vitamin A causes a disturbance in lipidation, glycosylation sulphatation and hydration of the secretion. A hypothesis is put forward according to which, vitamin A, joining the specific protein synthetized on ribosomes, initiates organization of the lipid phase. The latter might determine the direction and rate of protein transport in the system of smooth membranes where it is glycosidated. Formation of the lipid phase is disturbed when vitamin A is absent. This leads to changes in the protein migration pathways in the Golgi apparatus, which results in glycosidation disturbance as well. According to the same principle vitamin A may articipate in formation of glycolipoproteins not only of secretion but also of the intercellular substance, plasmatic membranes nuclei, lysosomes and other organelles.