AUTOR(ES)

DATA DE PUBLICAÇÃO

2007

RESUMO

The embryonary period extends itself from 15th to 45th day of gestation in cows, when a fast growing and differentiation occurs, during which the main organs, tissues and systems are established and the main characteristics are recognized. In bovines, most of the organs and parts of body are formed between 2th and 6th week of gestation. During this period, the digestive tract, the lungs, the liver and the pancreas are developed from the primitive intestine; being established the origins of the muscle, skeletal, nervous and urogenital systems. Approximately 25 to 45% of bovine embryos are lost until the final process of implantation; however, the literature related to their organogenesis is scant, since the technologic innovations related to bovine reproduction are growing. Thus, we think it is opportune and necessary a study about the biology of development of digestive tract of bovine embryos derived from natural coition, using optic microscopy and transmission electronic microscopy. Our results disclose that in embryos having a estimated gestational age of 20 days (CR 9,0 mm), it occurred a formation of tracheoesophagic septum, dividing the anterior intestine in laringotracheal tube and esophagus, separating itself totally on 28/29 days of gestation. At about 60th day of gestation (CR 70,0 mm), a multicavity stomach, characteristic of ruminants, is evident and presents endodermic epithelium on differentiation, mesodermic connective tissue and smooth muscle tissue. The epithelial cells nuclei go along the cell shape and the basal lamina delimits the area of epithelium and mesenchyme, being the cells bound each other through desmosoms, which promote the cellular sustentation.

ASSUNTO(S)

development digestive tract embrião bovino bovine embryo aparelho digestório desenvolvimento

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