The microenvironment created by non-blocking embryos in aggregates may rescue blocking embryos via cell-embryo adherent contacts.
Under our culture conditions, mouse embryos from the BALB/c inbred mouse strain develop successfully in culture only from the late 2-cell stage onwards (so-called 2-cell block), whether or not EDTA is added to the culture medium. (CBA x C57BL) F2 embryos do not exhibit a 2-cell block. Medium conditioned by culture of non-blocking embryos from the 2-cell to the 8-cell stage did not improve the development of blocking embryos, nor did co-culture of blocking and non-blocking embryos, with or without conditioned medium. On the other hand phytohaemagglutinin (PHA)-assisted aggregation of an early 2-cell BALB/c embryo with five surrounding non-blocking F2 embryos (2-cell or 8-cell) or five BALB/c 8-cell embryos allowed the early 2-cell BALB/c embryos to develop into blastocysts within 72 h. Aggregation of blocking BALB/c 2-cell embryos with each other had no 'rescue' effect. When blocking and non-blocking 2-cell embryos were aggregated together, an integrated blastocyst was formed; but when the early 2-cell BALB/c embryos were aggregated with non-blocking 8-cell embryos, the blocking embryos formed a separate small blastocyst, which nonetheless retained adherent contact with the non-blocking embryos throughout the culture period. Ultrastructural analysis showed that 2-cell embryos aggregated with the aid of PHA form close adherent cell contacts up to several micrometres in length.
Sekirina
G G
GG
Laboratory of Cell Morphology, Russian Academy of Sciences, Saint Petersburg, Russia.
Neganova
I E
IE
D000818:Animals; D002448:Cell Adhesion / Q000187:drug effects / Q000502:physiology*; D002678:Chimera / Q000187:drug effects / Q000502:physiology*; D017077:Culture Media, Conditioned / Q000494:pharmacology; D046508:Culture Techniques / Q000379:methods*; D004622:Embryo, Mammalian / Q000033:anatomy & histology / Q000187:drug effects / Q000502:physiology*; D005260:Female; D016195:G2 Phase / Q000502:physiology; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D008808:Mice, Inbred CBA; D008938:Mitosis / Q000502:physiology; D010835:Phytohemagglutinins / Q000494:pharmacology; D037121:Plant Lectins
D017077:Culture Media, Conditioned; D010835:Phytohemagglutinins; D037121:Plant Lectins