ABSTRACT. The yolk sac is an embryonic membrane that is essential for the embryo's initial survival in many mammals. It also plays an important role in the production of proteins necessary for development. We studied proteins of the yolk sac in bovine embryos at up to 40 days of gestation. We examined the yolk sac of 17 bovine embryos at different gestational periods, measuring α-fetoprotein, α-1-antitrypsin, and transferrin. This experiment was carried out by Western blot technique, associated with electrophoresis on a 6% sodium dodecyl sulfate polyacrylamide gel. Mouse monoclonal antibody anti-human-α-fetoprotein, mouse antibody anti-human-transferrin and rabbit polyclonal anti-human-α-1-antitrypsin were used as primary antibodies, and conjugated peroxidase as a secondary antibody. We detected the three proteins in some of the yolk sac samples; however, the bands in some specimens (samples) were weak, maybe a result of poor antigenantibody reaction, since the antibodies used in this study were not Bovine yolk sac proteins specific to bovine proteins. The fact that weak bands appeared might be due to a weak cross-reaction.

A família é a base da sociedade e o lugar onde as pessoas aprendem pela primeira vez os valores que os guiarão durante toda a vida" João Paulo II AGRADECIMENTO ESPECIAL A minha orientadora Maria Angélica Miglino pela oportunidade a mim concedida, pela confiança, orientação e incentivo. Obrigada por contribuir para meu crescimento profissional e, especialmente pelo respeito, atenção, carinho e amizade. A você, minha eterna gratidão. As minhas queridas irmãs, Liliane S. Matsumoto Juliana E. Matsumoto e Viviane S. Matsumoto pelo apoio, carinho e companhia, e por sempre me darem força e incentivo para que eu pudesse passar por mais essa fase.