The cytoskeleton of Xenopus oocytes and its role in development.

Much is known about determinative events in early amphibian embryos, perhaps more than any other animal group. However, as yet, little attention has been focused on the cytoarchitecture of the oocyte, and the way in which this could regulate asymmetries in the egg, which in turn could lead to developmentally important interactions. The changing cytoarchitecture of the Xenopus oocyte is described with the emphasis on the following: -firstly the polarity; the oocyte is not radially symmetrical at early stages of oogenesis, but shows marked polarity. Secondly, several cytoskeletal elements change their distribution during oogenesis, and again during maturation to form a fertilizable egg. Thirdly, monoclonal antibody methods show that the oocyte develops several asymmetries which are retained in the egg and early embryo, and may be lineage related.