Parthenogenesis and Polyploidy in Mammalian Development

Recent discoveries in the field of developmental biology have shown that the early mammalian embryo will tolerate a remarkable variety of chromosomal and cytological relationships. Parthenogenetic mammalian embryos can be developed from unfertilized eggs, germ cells need not be haploid or embryos diploid, and the interplay of cytological variables may lead to several alternative routes of development. This monograph is a progress report of the research aims and results in this new and challenging field of investigation. The introduction is devoted to an outline of normal development of the eutherian mammalian egg, a discussion of definitions and terms, and a very brief presentation of chromosome preparation and counting techniques. The second chapter outlines sixteen major routes of mammalian development based on the possible occurrence of four cytological variables: (1) suppression of the first polar body, (2) suppression of the second polar body, (3) suppression of the first cleavage division, and (4) the genetic absence of spermatazoa.