Placental microstructure and efficiency in cloned bovines: a design-based stereological approach
- 90 Downloads
Somatic nuclear transfer allows scientists to produce identical copies of individuals (clones) and offers the potential for research in various fields. However, the production of cloned bovines is inefficient, partly because of high rates of embryonic mortality associated with abnormal placental development, although the exact mechanisms are still unclear. In the present study, we have applied design-based stereological methods to quantify placental morphology in cloned and non-cloned Nelore bovines (280–297 days of gestation). We have found no differences for any of the following parameters: number and volume of placentomes, villous volume and surface area, volume and number of star volume units and placental efficiency. Therefore, placental deficiency is unlikely to be attributable to its villous component. Nevertheless, new studies should focus on other placental constituents, e.g. capillaries, trophoblast cells and feto-maternal exchange surface area.
KeywordsClones Fetus Placenta Stereology Bovine
The authors are extremely grateful to Prof. Terry Mayhew (Nottingham, UK) for practical advice on stereological methods and organ sampling and for help with interpreting results. A.A.C.M.R. thanks Prof. Flávio Vieira Meirelles from the Departamento de Ciências Básicas, Faculdade de Zootecnia e Engenharia de Alimentos in Pirassununga, São Paulo, Brazil, for producing all the cloned bovines used in this investigation. P.M.O.L. is also grateful to Prof. Maria Angélica Miglino.
- Bertolini M, Mason JB, Beam SW, Carneiro GF, Sween ML, Kominek DJ, Moyer AL, Famula TR, Sainz RD, Anderson GB (2002) Morphology and morphometry of in vivo- and in vitro-produced bovine concepti from early pregnancy to term and association with high birth weights. Theriogen 58:973–994CrossRefGoogle Scholar
- Björkman N (1954) Morphological and histochemical studies on the bovine placenta. Acta Anat 22:1–92Google Scholar
- Constant F, Guillomot M, Chavatte-Palmer P, Heyman Y, Berthelot V, Camous S, Turbe JP (2003) Structural and functional studies on placenta of bovine somatic clones. Placenta 24(A.37):P114Google Scholar
- Constant F, Guillomot M, Heyman Y, Vignon X, Laigre P, Servely JL, Renard JP, Chavatte-Palmer P (2006) Large offspring or large placenta syndrome? Morphometric analysis of late gestation bovine placentomes from somatic nuclear transfer pregnancies complicated by hydrallantois. Biol Reprod 75:122–130PubMedCrossRefGoogle Scholar
- Gonçalves PBD, Figueiredo JR, Freitas VJF (2002) Biotécnicas aplicadas a reprodução animal. Varela, São PauloGoogle Scholar
- Gundersen HJG (1977) Notes on the estimation of the numerical density of arbitrary profiles: the edge effect. J Microsc 111:219–223Google Scholar