title: Attachment, outgrowth, invasion and formation of the egg cylinder in mouse half embryos in vitro.
abstract: To investigate the effect of the decrease in the number of embryonic cells on the development and morphogenesis of mouse embryos at the peri-implantation stage, half embryos which developed from bisected morulae were morphologically classified into eu-blastocysts (eu-blasts), pseudo-blastocysts (pseudo-blasts), trophectodermal vesicles (TVs) and non-integrated forms (NIFs) and then cultured on plastic substratum, uterine-epithelial-cell monolayer and type I collagen gel. When half embryos were cultured on plastic substratum and cell monolayer, the rates of attachment and trophoblast outgrowth in the eu- and pseudo-blasts were not significantly different from those of the controls. The TVs and NIFs showed significantly lower rates of outgrowth than the controls (P < 0.01). When half embryos were cultured on type I collagen gel, no significant difference was observed in the rate of primitive endoderm formation between the eu-blasts and controls after 36 hr of culture. In the eu-blasts, however, the developmental rate to the egg cylinder at stage 8 was significantly lower than in the controls after 72 hr (P < 0.05). The pseudo-blasts revealed significantly lower rates of endoderm formation and development to the egg cylinder than the controls after 36 and 72 hr, respectively (P < 0.05). In the TVs and NIFs, the rates of outgrowth were significantly lower than those of the controls (P < 0.05) and no egg cylinder was observed. The invasion of type I collagen gel by the cytoplasmic protrusions of trophoblast cells was observed regardless of the type and developmental stage of the embryos. The results show that a decrease in the number of embryonic cells affects the formation of the primitive endoderm and the development to the egg cylinder in vitro.
authors.affiliation: Department of Veterinary Clinical Science, Hokkaido University, Sapporo, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Hishinuma
authors.forename: Y
authors.initials: Y
authors.lastname: Takahashi
authors.forename: H
authors.initials: H
authors.lastname: Kanagawa
mesh_terms: D000818:Animals; D001755:Blastocyst / Q000166:cytology / Q000502:physiology* / Q000648:ultrastructure; D002448:Cell Adhesion; D002455:Cell Division; D002478:Cells, Cultured; D003094:Collagen; D004622:Embryo, Mammalian / Q000166:cytology / Q000502:physiology* / Q000648:ultrastructure; D004707:Endoderm / Q000166:cytology / Q000502:physiology; D004847:Epithelial Cells; D004848:Epithelium / Q000502:physiology; D005260:Female; D007700:Kinetics; D051379:Mice; D008815:Mice, Inbred Strains; D008854:Microscopy, Electron; D009024:Morphogenesis; D009924:Organ Culture Techniques; D013480:Superovulation; D013997:Time Factors; D014327:Trophoblasts / Q000166:cytology / Q000502:physiology / Q000648:ultrastructure; D014599:Uterus / Q000166:cytology / Q000502:physiology
chemical_list: D003094:Collagen