Radiation malformations belonging to the cyclopia-arrhinencephalia-otocephalia group in the mouse foetus.

X-RADIATION is one of the most powerful agents in causing embryonic malformations and has been used recently by many investigators. Among various kinds of radiation malformations, those of the brain have been of special interest. Job, Leibold, & Fitzmaurice (1935), Kaven (1938), Warkany & Schraffenberger (1947), Russell (1950), Hicks (1953,1954), Wilson & Karr (1951), Wilson, Jordan, & Brent (1953), Rugh & Grupp (1959), and Murakami & Kameyama (1958) studied teratogenic effects of X-rays on embryos by irradiating pregnant rats or mice. Exencephalia was listed as the chief malformation of the brain by most of these investigators. Radiation malformation of the snout and nostril was reported by Russell (1950) as having some relationship to otocephalies. In the present paper, a series of malformations belonging to the cyclopia-arrhinencephalia-otocephalia group are described, and the critical period at which the pattern of malformations originates is discussed.