title: Development of cytoskeletal connections between cells of preimplantation mouse embryos.
abstract: Observations by scanning electron microscopy of mouse cleaving embryos reveal the presence of long microvilli around cell contact regions that often bridge the gap between blastomeres. These microvilli correspond, in detergent-extracted morulae, to strings connecting the cortical cytoskeletons of adjoining cells. They appear about 4 h after compaction in synchronized cultures. Transmission electron microscopy, heavy meromyosin decoration and DNase I digestion show that cytoskeletal connections contain bundles of actin microfilaments. The establishment of cytoskeletal connections does not require immediate protein synthesis, as shown by incubation with cycloheximide. Diverse treatments that interfere with compaction were tested for the development of cytoskeletal connections: culture media with low Ca2+and/or Mg2+, or EGTA, or α-lactalbumin, do not prevent the establishment of connections, while colchicine delays their appearance and cytochalasin D suppresses it. The relation between cytoskeletal connections, compaction and blastulation is discussed.
authors.affiliation: Departamento de Biologia, Universidad de Chile, Casilla 653, Santiago, Chile.
authors.forename: Roberto
authors.initials: R
authors.lastname: Mayor
authors.affiliation: Departamento de Biologia, Universidad de Chile, Casilla 653, Santiago, Chile.
authors.forename: Roxana
authors.initials: R
authors.lastname: Pey
authors.affiliation: Departamento de Biologia, Universidad de Chile, Casilla 653, Santiago, Chile.
authors.forename: Luis
authors.initials: L
authors.lastname: Izquierdo
keywords: Connections; Cytoskeleton; Intercellular; Morula