EMBRYOLOGIC FEATURES OF TERM FETUSES AND NEWBORNS IN CL FR MICE WITH SPECIAL REFERENCE TO CYANOSIS/

Objective: The objective of this study was to clarify the embryologic features of CL/Fr mice in relation to cyanosis. Method: Orofacial exam inations were conducted on 18-day-old term fetuses and newborns, Excep t for open eyelids in a few cases, all of the external abnormalities i n this strain were cleft lip and/or palate (CLP). Results: The CLP inc idence in term fetuses was 28.4%. The body and placental weights were not different between CLP(+) and CLP(-) fetuses. Several types of CLP were found; the most frequent was bilateral complete CLP (60%) followe d by left complete (16%). Bilateral complete CL, which is the most sev ere CL type, was associated with poorly developed secondary palate and wide cleft, In newborns, 39.4% of CLP(+) mice showed cyanosis, where no CLP(-) mice had such signs. The body weight of cyanotic mice with C LP was significantly lighter than that of noncyanotic mice with CLP. C yanotic mice had severe types of CLP and unelevated palatal shelves. C onclusion: We suggest that mechanical airway obstruction may be one of the causes of cyanosis in newborn CL/Fr mice.