Caracterização das células-tronco do saco vitelino e análise ultraestrutural da membrana vitelina de embriões ovinos (Ovis aries)

Characterization of putative haematopoietic cells from bovine yolk sac

“…To further understand the constitution of this embryonic membrane that was previously described macroscopically in bovine (Evans and Sack, ; Wrobel and Suss, ; Gitlin and Perricelli, ; Assis Neto et al, ), we developed a cell culture method, following the protocol used in sheep to identify and characterize haematopoietic cells from the bovine yolk sac (Pessolato, ). Haematopoietic cells from the bovine yolk sac were found to be similar to those from the yolk sac of sheep and mice (Pessolato, ; Choi et al, ). In culture, the cells divided proportionally into groups of adherent and non‐adherent cells.…”

“…Consistent with previous reports, our macroscopic analysis revealed that the bovine yolk sac is best visualized macroscopically at day 25 of gestation and consists of a central saccular region and two elongated ventral projections (Wrobel and Suss, ; Mançanares et al, ). To further understand the constitution of this embryonic membrane that was previously described macroscopically in bovine (Evans and Sack, ; Wrobel and Suss, ; Gitlin and Perricelli, ; Assis Neto et al, ), we developed a cell culture method, following the protocol used in sheep to identify and characterize haematopoietic cells from the bovine yolk sac (Pessolato, ). Haematopoietic cells from the bovine yolk sac were found to be similar to those from the yolk sac of sheep and mice (Pessolato, ; Choi et al, ).…”

“…The cytoplasm was shown to contain numerous organelles, such as mitochondria, Golgi complexes, rough endoplasmic reticulum and desmosomes. Similar features were reported in cells of dog liver, sheep yolk sac and mouse bone marrow (Wenceslau et al, ; Pessolato, ). Unlike in our findings, in cells of the umbilical cord of bovine zebu‐crossed animals, researchers detected an oval nucleus without nucleolus (Rodrigues et al, ).…”

“…Colony formation assays in methylcellulose matrix (Methocult H4534) performed on DIV 14 revealed colonies similar to those formed from human embryonic stem cells and S17 murine bone marrow haematopoietic progenitor cells (Kaufman et al, ), and in haematopoietic progenitors from human yolk sac, CD34 + cells in which morphology and time for the formation of colonies are similar to our findings (Huyhn et al ., ). However, haematopoietic cells from the sheep formed colonies the day after they were plated (Pessolato, ); from irradiated mice, colonies were formed after 7 DIV (Luis et al, ). Using the same cytological analysis techniques as used for human bone marrow (Fast Panoptic), we observed cells with characteristics similar to those of lymphocytes and monocytes (Rohon et al, ).…”

“…In mouse embryonic cells, the LMO2 gene was absent in lymphocytes and myelocytes (Yamada et al, ; Pruess et al, ). In the vitelline membrane of sheep, LMO2 is expressed at gestational day 25 day (Pessolato, ).…”