The consequences of X-dosage deficiency in the germ line: Impaired development in vitro of preimplantation embryos from XO mice

Abstract

Two-cell embryos from XO and XX mice were cultured for 3–4 days. The stage of development reached by the embryos was scored at intervals, using as criteria the number of cells, the degree of compaction, and the presence or absence of a blastocoele. The results show that the embryos from XO mice cleave, compact, and form blastocoeles later than do the embryos from XX mice. Furthermore, many of the XO-derived embryos failed to form blastocysts and became grossly abnormal. It is suggested that this overall impaired development is a consequence of X-dosage deficiency in the maternal germ line through the production of eggs which are deficient in X-linked products. In addition to this overall developmental impairment, a few embryos died at the eight-cell stage. These may have been YO embryos. The breeding characteristics of XO mice, XX↔XY female mouse chimeras, and the sterility of XO (Turner's syndrome) women are discussed in the light of these observations.