title: [Overcoming the "2-cell block" in mouse embryos in aggregation chimeras].
abstract: The embryos of the inbred mouse strain BALB/c are predisposed to so-called "two-cell block" after explantation from the maternal organism before the late two-cell stage and cultivation in a standard synthetic medium. Hybrid embryos (CBA x C57B1) F2 are competent to complete preimplantation development in vitro. The BALB/c embryo predisposed to block ("blocking") at the early two-cell stage was aggregated using phytohemagglutinin with four to five two- and eight-cell BALB/c embryos capable of reaching the blastocyst stage in vitro ("non-blocking"). This aggregate successfully developed until the blastocyst stage for 72 h. The aggregation of the early two-cell BALB/c embryos with each other did not prevent the block. After the aggregation of the blocking and non-blocking embryos at the two-cell stage, a common integrated blastocyst developed. In aggregates with eight-cell embryos, the blocking embryo formed a separate blastocyst, although it preserved contacts with non-blocking embryos during the entire period of cultivation. Ultrastructural analysis has shown that two-cell embryos aggregated using phytohemagglutinin form adhesive contacts up to several microns long. Possible mechanisms of cooperation between the competent and deficient partners in aggregates with two-cell embryos are discussed.
authors.forename: G G
authors.initials: GG
authors.lastname: Sekirina
authors.forename: I E
authors.initials: IE
authors.lastname: Neganova
mesh_terms: D000818:Animals; D001755:Blastocyst / Q000187:drug effects / Q000648:ultrastructure; D002449:Cell Aggregation / Q000187:drug effects; D002478:Cells, Cultured; D002678:Chimera / Q000187:drug effects; D002970:Cleavage Stage, Ovum / Q000187:drug effects / Q000648:ultrastructure*; D003470:Culture Media; D005260:Female; D005838:Genotype; D008297:Male; D051379:Mice / Q000196:embryology*; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D008808:Mice, Inbred CBA; D010835:Phytohemagglutinins / Q000494:pharmacology; D037121:Plant Lectins; D013997:Time Factors
chemical_list: D003470:Culture Media; D010835:Phytohemagglutinins; D037121:Plant Lectins