E-cadherin distribution pattern in in vitro matured oocytes and parthenogenetic embryos of domestic sheep (Ovis aries)

Abstract

The E-cadherin distribution pattern was evaluated in in vitro matured oocytes (IVM) and parthenogenetic embryos of adult Creole sheep (Ovis aries). Ovaries were collected from a slaughterhouse located in the State of Mexico, Mexico, and transported to the laboratory under controlled conditions. Cumulus-oocyte complexes were obtained by follicular puncture and subjected to in vitro maturation (IVM) in TCM-199 (22 h). For parthenogenesis, oocytes were activated with calcium ionophore and 6-DMAP, and cultured in in vitro growth medium at 38.5°C and 5% CO2 in high humidity. At 36h of culture, parthenogenetic embryos were fixed and incubated with specific antibodies, analyzed by confocal microscopy (Zeiss LSM T-PMT, FITC filter: excitation 495nm). Images were analyzed with ZEN Lite (Zeiss), the amount of E-cadherin was expressed in fluorescence units (fu). A total of 8 IVM oocytes and 21 parthenogenetic embryos were evaluated at the following developmental stages: 4-cell (n=9), 6-cell (n=4) and 8-cell (n=8). Cytoplasmic E-cadherin in IVM oocytes was 70 ± 2.8fu. Cytoplasmic and junctional E-cadherin levels in 4-cell embryos were 57.6 ± 5.1 and 45.8 ± 5.1uF, respectively; 6-cell embryos were 27.8 ± 3.0 and 29.2 ± 3.4uF, respectively; and 8-cell embryos were 50.0 ± 5.9 and 58.7 ± 6.2uF, respectively. The results indicate that as embryonic development progresses, E-cadherin is distributed from the cytoplasm to cell junctions, suggesting a key role in the formation of intercellular contacts prior to embryo compaction. It is concluded that the distribution pattern observed in ovine parthenogenetic embryos is similar to that of embryos obtained by in vivo or in vitro fertilization. We would like to thank CONAHCyT (now SECIHTI) for the support provided through agreement C-459/2024.