The role of embryonic polarities in preimplantation growth and implantation of mammalian embryos.
Strong evidence now exists of polar axes associated with various embryological, morphogenetic and developmental events in mammals from oocyte formation to implantation. These axes strictly regulate morphogenesis throughout the pre- and post-implantation stages. They are expressed by gradients in gene products and organelles, control ooplasmic and cytoplasmic rotations coupled with specific cleavage planes, and the imposition of body axes on embryo and fetus. The expression of polarities in preimplantation and implanting embryos, and their relationship with the implantation process, are discussed in this paper. A deeper understanding of such a fundamental aspect of the genetic regulation of the embryo should help to clarify significant aspects of implantation and the clinical evaluation of human embryos in vitro.
Churchill College, Cambridge, UK. edwards@duckendfarm.cambsnet.co.uk
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Edwards
D000818:Animals; D001755:Blastocyst / Q000166:cytology* / Q000378:metabolism; D019521:Body Patterning / Q000235:genetics / Q000502:physiology; D016764:Cell Polarity / Q000502:physiology; D010064:Embryo Implantation / Q000235:genetics / Q000502:physiology; D005314:Embryonic and Fetal Development / Q000235:genetics / Q000502:physiology; D005260:Female; D006801:Humans; D066298:In Vitro Techniques; D051379:Mice; D009865:Oocytes / Q000166:cytology / Q000378:metabolism; D011247:Pregnancy