Placental maturation and expulsion in Holstein and Nelore cows

• Published in: Arquivo brasileiro de medicina veterinária e zootecnia 2004-04, Vol.56 (2), p.157-167
• Main Authors: Martins, V.M.V, Marques Junior, A.P, Vasconcelos, A.C, Martins, E, Santos, R.L, Lima, F.P.C
• Format: Article
• Language: English
• Subjects: apoptose; apoptosis; BEEF CATTLE; binucleate cell; bovine; bovino; células binucleadas; DAIRY CATTLE; EMBRIAO; EMBYO DEVELOPMENT; epithelial cell; GADO DE CORTE; GADO HOLANDES; GADO LEITEIRO; GADO NELORE; MATURIDADE SEXUAL; PLACENTA; placentoma; placentome; PREGNANCY; PRENHEZ; SEXUAL MATURITY; VETERINARY SCIENCES
• ISSN: 0102-0935; 1678-4162; 1678-4162; 0102-0935
• DOI: 10.1590/s0102-09352004000200004

Morphological changes in the placenta at periparturition and the involvement of apoptosis controlling cell populations in the placentome were evaluated in Holstein and Nelore cows. Twenty-two Holstein cows at the end of gestation with normal non-induced parturition (group I) and 10 Holstein cows with induced parturition (group II) were used in this study. In addition, groups III and IV were constituted by 10 Nelore cows at the end of gestation with normal non-induced parturition and 21 Nelore cows with induced parturition, respectivelly. Binucleate trophoblastic cells, epithelial caruncular cells and apoptotic bodies were quantified by light microscopy. Apoptosis was further evaluated by transmission electron microscopy, ELISA and DNA electrophoresis in agarose gel. The number of caruncular epithelial cells did not vary between breeds with normal or induced parturition. The number of binucleate cells was significantly different between Holstein and Nelore cows with normal non-induced parturition (groups I vs. III), but their numbers were not significantly different between breeds when parturition was induced. In cows with normal non-induced parturition, the intensity of apoptosis, as assessed by morphometric analysis and ELISA, was significantly higher in group I when compared to group III. However, no difference in the intensity of apoptosis was found between groups II and IV. Characteristic apoptotic ladder pattern of DNA fragmentation was detected by agarose gel electrophoresis. Ultra-structural features of apoptosis in maternal and fetal epithelium as well as capillary vascular endothelium were identified by transmission electron microscopy. In conclusion, in Nelore placental maturation occurs precociously when compared to Holstein. In both breeds, apoptosis is an active physiological event that seems to be required for maturation and normal post-partum release of the placenta. Foram avaliadas as diferenças morfológicas e a participação da apoptose na população de células do placentoma de vacas das raças Holandesa e Nelore no período periparto. Foram utilizadas 22 vacas da raça Holandesa com parto a termo (tratamento I) e 10 com parto induzido (tratamento II). Nos tratamentos III e IV foram utilizadas 10 vacas Nelore com parto a termo e 21 com parto induzido, respectivamente. As células binucleadas trofoblásticas e epiteliais carunculares e os corpos apoptóticos foram quantificadas por microscopia óptica. A apoptose também foi avaliada por microscopia