Rediscovering Boveri's centrosome in Ascaris (1888): its impact on human fertility and development

We rediscover and review the brilliant work of Theodore Boveri, over a 100 years ago, on the centrosome of the round worm Ascaris and show how it impacts on our understanding of human fertilization and embryogenesis. Boveri was able to make fundamental predictions on the mechanics of fertilization and the dominant role of the sperm centrosome (Boveri's rule), which is now applicable to most animals. Using advanced digital imaging by light and electron microscopy, we explore centrosomal dynamics during Ascaris fertilization and the first cell cycle during cleavage. Twenty figures are presented in this visual publication. Humans follow Boveri's rule, as do most mammals excluding some rodents, and there is a remarkable similarity of the events of fertilization and cleavage in Ascaris and humans, the latter of which has been documented since 1991. The role of the sperm centrosome (centriole) in egg activation, polarity, embryogenesis, infertility and cancer is discussed. An attempt is made to portray the images Boveri may have visualized, in his painstaking drawings presented in his thesis in 1888. We now know the origins of the centrosome in human somatic cells – predominantly from the sperm cell. The impact of Boveri's work on human development is highlighted in this age of assisted reproductive technology.