title: Development of bovine embryos derived from reproductive techniques.
abstract: Assisted reproduction techniques have improved agricultural breeding in the bovine. However, important development steps may differ from the situation in vivo and there is a high mortality rate during the first trimester of gestation. To better understand these events, we investigated the development of embryos and fetal membranes following fixed-time AI (FTAI), IVF and nuclear transfer (NT). The onset of yolk-sac development was not normal in cloned embryos. Later steps differed from conditions in vivo in all three groups; the yolk-sac was yellowish and juxtaposed with the amniotic membrane. Vascularisation of the chorioallantoic membrane was relatively late and low in NT gestations, but normal in the others. The overall development of the embryos was normal, as indicated by morphology and regression analysis of growth rate. However, NT conceptuses were significantly smaller, with the livers in some embryos occupying the abdominal cavity and others exhibiting heart abnormalities. In conclusion, the yolk-sac and the cardiovascular system seem to be vulnerable to morphogenetic alterations. Future studies will focus on gene expression and early vascularisation processes to investigate whether these changes may be responsible for the high incidence of intrauterine mortality, especially in clones.
authors.affiliation: Department of Surgery, School of Veterinary Medicine and Animal Science, University of Sao Paulo, Av. Prof. Orlando Marques de Paiva, 87, Butantã, 05508-270, Sao Paulo, Brazil.
authors.forename: Míryan L V
authors.initials: ML
authors.lastname: Alberto
authors.forename: Flavio V
authors.initials: FV
authors.lastname: Meirelles
authors.forename: Felipe
authors.initials: F
authors.lastname: Perecin
authors.forename: Carlos E
authors.initials: CE
authors.lastname: Ambrósio
authors.forename: Phelipe O
authors.initials: PO
authors.lastname: Favaron
authors.forename: André L R
authors.initials: AL
authors.lastname: Franciolli
authors.forename: Andrea M
authors.initials: AM
authors.lastname: Mess
authors.forename: José M
authors.initials: JM
authors.lastname: Dos Santos
authors.forename: Rose E G
authors.initials: RE
authors.lastname: Rici
authors.forename: Marcelo
authors.initials: M
authors.lastname: Bertolini
authors.forename: Maria A
authors.initials: MA
authors.lastname: Miglino
mesh_terms: D000818:Animals; D017849:Animals, Inbred Strains; D001938:Brazil; D002417:Cattle / Q000235:genetics / Q000502:physiology*; D019976:Cloning, Organism / Q000379:methods / Q000662:veterinary; D003433:Crosses, Genetic; D020964:Embryo Loss / Q000209:etiology / Q000662:veterinary; D004622:Embryo, Mammalian / Q000002:abnormalities / Q000196:embryology*; D047108:Embryonic Development; D005321:Extraembryonic Membranes / Q000002:abnormalities / Q000098:blood supply; D005260:Female; D005307:Fertilization in Vitro / Q000009:adverse effects / Q000662:veterinary; D005313:Fetal Death / Q000209:etiology / Q000662:veterinary; D006330:Heart Defects, Congenital / Q000209:etiology / Q000662:veterinary; D007315:Insemination, Artificial / Q000009:adverse effects / Q000662:veterinary; D053652:Nuclear Transfer Techniques / Q000009:adverse effects / Q000662:veterinary; D010929:Placentation; D011247:Pregnancy; D012099:Reproductive Techniques / Q000009:adverse effects / Q000662:veterinary*; D015017:Yolk Sac / Q000002:abnormalities