Harmonization of criteria and terminology in fetal rat skeletal evaluations.

BACKGROUND: A survey of laboratories in North American and Europe that routinely conduct fetal skeletal examinations was performed with the purpose of (1) understanding current terminology used for classifying skeletal findings in developmental toxicity (DT) studies and (2) understanding the criteria used to identify relatively common findings that sufficiently deviate from normal. The goal was to promote terminology harmonization and improve interlaboratory consistency in the criteria used to identify developmental anomalies. METHODS: The survey, designed based on terminology for developmental anomalies recommended by an international collaboration (Makris et al., Congenital Anomalies, 2009;49(3):123-246), was conducted by a subgroup (authors of this publication) of the Royal Society of Biology's International Register of Fetal Morphologists (IRFM). RESULTS: Individual and summarized anonymized responses are provided here. The authors, who are expert fetal morphologists with experience performing fetal examinations, reviewed the responses and generated recommendations on preferred terminology and criteria for determining when morphological variations deviate from normal and warrant recording of the findings for skeletal observations in Sprague Dawley (SD) fetal rats. The objective of these recommendations is to complement Makris et al. (Congenital Anomalies, 2009;49(3):123-246). CONCLUSION: The broad application will improve interlaboratory harmonization of recording fetal skeleton findings in developmental toxicity studies intended for regulatory submissions, including SEND (Standard for Exchange of Nonclinical Data).

Benzofuranyl ureas with potent cardiovascular teratogenicity in rats.

Studies of embryo-fetal development in rats were conducted with two 5-lipoxygenase inhibitors. SB-202235 (1,000 mg/kg/day) or SB-210661 (50, 100, or 500 mg/kg/day) was administered orally by gavage to female rats on days 6-17 postcoitus (pc) or days 7-16 pc. SB-202235 (1,000 mg/kg/day) and SB-210661 (100 mg/kg/day) reduced maternal body weight gain for the treatment period by 16% and 21%, respectively, relative to controls. SB-202235 (1,000 mg/kg/day) or SB-210661 (50 or 100 mg/kg/day), did not affect numbers of resorptions, dead or live fetuses/litter, but 500 mg/kg/day of SB-210661 caused 100% embryo lethality. SB-202235 (1,000 mg/kg/day) and SB-210661 (50 and 100 mg/kg/day) reduced fetal body weight by 15-30% and produced extensive cardiovascular malformations, as well as diaphragmatic hernias. SB-210661 also caused thymic abnormalities and cryptorchidism. Cardiovascular defects included abnormalities in aorticopulmonary septation, the aortic arch, pulmonary trunk, and ventricular septal defects are discussed relative to comparable human syndromes of cardiovascular malformation.