Stages in the prenatal development of the Chinese hamster (Cricetulus griseus).

A system of staging embryos is described for the Chinese hamster (Cricetulus griseus). This system of staging, based on Streeter's developmental horizons in human embryos, comprises three sets of criteria: 1) data on postconceptional age, size and number of somites, 2) external characteristics and 3) internal characteristics. A comparison has been made with data in mouse (Theiler, 1972) as well as in primates. It seems that the order of organogenesis, i.e. the sequence in which individual organs are formed, is basically similar in all mammals stuied so far.