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Biomedical subjects

R G Edwards

Publications and source records attributed to R G Edwards.

At least 55 records · Page 3Linked to original sources
PubMed2000

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.

Animals↗
PubMed1998

Principles of mammalian fertilization.

The principles of mammalian fertilization are defined in relation to studies of the intracytoplasmic injection of spermatozoa into human oocytes (ICSI). Sections are included on the production of mature oocytes and mature spermatozoa, sperm-oocyte interaction, and formation of the pronucleate oocyte. Current concepts in gametogenesis are discussed, including spermiogenesis, oogenesis, the biology and penetration of the zona pellucida including capacitation and the acrosome reaction, gamete fusion, the block to polyspermy and growth of the pronucleus. A concluding section relates the normal events of fertilization to those occurring after ICSI and discusses various types of anomalies found in the oocyte after ICSI.

Animals↗
PubMed1997

Oocyte polarity and cell determination in early mammalian embryos.

Knowledge on determination and differentiation in the mammalian embryo has not kept pace with discoveries in other phyla. Current concepts overlook well-established pathways leading to polarity in oocytes and embryos of other phyla, modern principles of totipotency in plants and animals, and axis formation in lower vertebrates. Various models derived from invertebrates and frogs could be relevant to the situation in eutherian mammals, and we explore the nature of strict genetic controls in these species and its implications for early mammalian differentiation. Concepts on totipotency and related phenomena in animal and human embryos are examined and the possibility raised that two cell lines are formed in early human embryos from the 2-4 cell stage. Clinical consequences are assessed, including causes of the high incidence of chromosomal mosaicism in human embryos. Our interpretations are obviously speculative, and must be clarified by experimentation.

Animals↗