O papel da bifurcação das projeções da mucosa durante a morfogênese das vilosidades intestinais em embriões de galinhas

Abstract

The intestinal villi are finger-like projections of the small intestinal mucosa that extend its surface, optimizing the process of nutrient absorption. The intestinal villi morphogenesis of the chick occurs indirectly. At first, longitudinal previllous ridges appear in the intestine. The previllous ridges fold into zigzag pattern, and finally individual villi are formed. Our previous study reported, for the first time, the bifurcation of the previllous ridges on chick embryos. Although morphological aspects of the intestinal villi morphogenesis of the chickens are known, there are no data from the previllous ridges bifurcation. The present work aimed to understand the role of bifurcation in the intestinal villi morphogenesis of the chick embryos. Histological analysis, evaluation of cell proliferation by incorporation of BrdU and PAS reaction were performed during the period of bifurcation. To evaluate cell proliferation, injection of BrdU in ovo was standardized. The histological analyses allowed to establish that the bifurcation occurs between the 13th and 15th day and to define the sequence of morphological events during the process. The evaluation of cell proliferation showed that cells of the mucosal epithelium and involved in the bifurcation were proliferating. The PAS reaction revealed the presence of basement membrane in the cells involved in the bifurcation process. The data allow us to conclude that the morphological changes of the bifurcation are correlated to the proliferation of epithelial cells and culminate to formation of previllous.