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.

Placental Evolution within the Supraordinal Clades of Eutheria with the Perspective of Alternative Animal Models for Human Placentation

“…bgc = binucleate giant cell, ct = cellular trophoblast, endo = endothelium, fc = fetal capillary, mv = maternal vessel, trp = trophoblast, and ue = uterine epithelium. cardiovascular system seems to be very sensitive in regard to developmental problems in early gestation, suggesting an altered expression of associated genes [156][157][158][159][160][161]. Vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF) genes are regarded as major stimulating factors for such processes and have been proven to be altered at least in term pregnancies of bovines from nuclear transfer [162,163].…”

Desenvolvimento do sistema tegumentar em bovinos com idades gestacionais estimadas de 20 a 140 dias

“…O presente trabalho analisou o desenvolvimento embrionário da pele, aparelho ungueal e glândula mamária de bovinos em diferentes fases de gestação. Observamos que os primórdios, do desenvolvimento do membro torácico, ocorre em embriões de 20-26 dias de gestação (Grupo I), bem como nos embriões de 30 dias (Grupo II) onde os brotos dos membros torácicos e pélvicos começam a se desenvolver, assim como encontrado por Evans & Sack (1973) e Alberto et al (2013).…”

Bovine yolk sac: from morphology to metabolomic and proteomic profiles

“…Thus, the bovine embryos in Group I had ages ranging from 23 to 32 days of gestation, Group II, of 33-42 days, and Group III, of 43-52 days. The sum of the descriptions of the external characteristics during pregnancy in bovine have been well characterized in the literature for normal pregnancies or in the use of different reproduction techniques such as in vitro fertilization, artificial insemination, and nuclear transfer (Assis-Neto et al, 2010;Alberto et al, 2012).…”

“…In bovine species, the yolk sac is functional for a short period of time (Alberto et al, 2012), but its functions at this stage are of utmost importance for the survival of the embryo. Most importantly, are the absorption and digestion of maternal nutrients, protein synthesis (Galdos-Riveros et al, 2010;Alberto et al, 2012), formation of the vitelline circulation and intravascular secretion of nutrients (Baron, 2003), and some functions performed by the liver, before the fetal liver develops (Gulbis et al, 1998).…”

“…Recently, it was reported that changes in the morphogenesis of the yolk sac directly affect the development of other organs and systems, whose functions are vital to the development of the embryo, including bovine generated from artificial insemination, in vitro fertilization and nuclear transfer (Alberto et al, 2012). Their functions are complex in mammals: hematopoiesis and development of the first blood vessels of the embryo, transfer of nutrients, immunoglobulins and gases from the maternal circulation, as well as vitamins and amino acids, and is also the site of migration of primordial germ cells (Lloyd et al, 1998;Katayama and Kayano, 1999).…”