Supernumerary Lumbar Rib: Manifestation of Basic Alteration in Embryonic Development of Ribs

摘要: Supernumerary ribs (SNR) are a common variant in some strains of mice used standard teratology bioassays. We have previously demonstrated that increased incidence SNR may be induced by wide variety xenobiotics and/or general maternal stress. The significance this defect cross-species extrapolations has been problematic and recent studies, including one, shown anomaly is more complex than thought. bimodal distribution composed ‘rudimentary ribs’ (RR) with mode 0.3–0.4 mm ‘extra (ER) 0.9–1.1 mm. studies reported here examine the relationship between presence 13th rib length gross morphological development anomaly. were CD-1 surgical stress (subcutaneous micropump implanted on gestational day (GD), restraint (GD8), food water deprivation (GD8) or administration pesticide dinoseb (50 mg kg−1 GD7 GD8). Fetuses from untreated litters also examined. Dinoseb-treated killed GD14, 15, 16 17. All other groups GD17. lengths 14th measured anomalies recorded. Femur was as an indicator fetal size. frequency higher all treatment compared to controls. found ER RR morphologically distinct. flat ended distally joined cartilaginous portion, while usually rounded without extensions. significantly longer fetuses having those not SNR, whether treated untreated. This present ages examined both groups. These results suggest indicative basic alterations axial skeleton.