Intrinsic and extrinsic factors in preimplantation development

The embryo--maternal dialogue during early pregnancy in primates

“…The embryo initially depends on an inherent programme of development (Johnson, 1979) which soon requires communication with the mother (Bazer & Thatcher, 1977;Bazer & First, 1983); and the functioning of the paternal and maternal genomes are necessary for normal development (Barton, Surani & Norris, 1984). The precision of these studies has yet to be matched in those with primates although undoubtedly many of the fundamental control mechanisms are similar.…”

Phospholipid synthesis in the preimplantation mouse embryo

“…Not only do the cellular changes associated with cleavage and the subsequent growth of the embryo require the assembly of new intracellular and plasma membranes (Calarco & Brown, 1969) but striking qualitative changes in the properties of embryonic membranes also occur during crucial transitions in early development. For example, compaction of the morula leads to polarization of cells (Ducibella, Albertini, Anderson & Biggers, 1975;Ducibella, Ukena, Karnovsky & Anderson, 1977), generating zonular tight junctions around the periphery of the embryo and establishing inter¬ cellular contact between internal cells, an arrangement which may be very important for the sub¬ sequent differentiation of the embryo (discussed by Johnson, Handyside & Braude, 1977;Johnson, 1979). Modulations in the organization of intracellular and plasma membranes can also be inferred from variations in surface antigen expression (Edidin, 1976), changes in mitochondrial morphology and membrane-bound enzyme activity (Biggers & Borland, 1976) as well as the transition from Na+-dependent to Na+-independent amino acid transport (Borland & Tasca, 1974) and localized activity of Na+-K+ ATPase during accumulation of blastocoelic fluid (Biggers, Borland & Powers, 1977).…”

Spectrin and calmodulin in spreading mouse blastomeres

“…Spreading in the embryo is associated with compaction, a process that takes place at the g-cell stage and is thought to have an important influence on blastocyst formation (Johnson, 1979). The spreading movements of blastomeres on Con A-coated substrate and the associated changes in cytoskeletal organization appear to mimic the behavior compacting cell in the embryo Sobel, 1984a).…”