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Abstract
The purpose of these studies were to analyze the developmental patterns in the peri-implantational mouse embryo under normal and experimentally altered conditions. To this end, Swiss Webster (SW) mouse embryos were studied in vitro. Probes used to assess various aspects of embryogenesis included known chemical teratogens (e.g. vincristine), antibodies to components of the developing embryos (e.g. laminin, entactin), and lectins known to bind to specific carbohydrate moieties.
The data obtained in these studies show the pattern of development in preimplantation and early implantation embryos does not change upon explantation in vitro. Some aspects of normal development can be perturbed with drugs. Exposure of early postimplantation embryos to vincristine has, besides the immediate teratogenic and embryoidal action, a delayed effect which is evidenced by abnormalities evolving several days later. These abnormalities are reproduced in vitro. A particular form of aberrant development-twinning-was studied in great detail, with the spontaneous twinning being compared to experimentally induced conjoined embryos. The conjoined placentation occurred at a rate of 0.4% for twins and 0.06% for triplets. The immunohistochemical and lectin histochemical studies performed on preimplantation embryos, embryos cultured in vitro and early postimplantation embryos illustrated the complex changes which occur during the peri-implantation stages of development. The synthesis of entactin and laminin is asynchronous in the early stage of mouse embryonic development, but becomes synchronized in the postimplantation stage of development. The appearance of lectin binding sites was found during trophoblastic and endodermal development exemplifying the change of cellular glycoprotein.
These studies show that a multidimensional approach to the study of embryogenesis in vivo and in vitro, coupled with the study of teratogenesis and the functional and structural changes in the maternal environment, provide important information about the basic aspects of morphogenesis in the peri-implantational stages of development.
