Table 1.

Incidence of anomalies caused by TCDD in homozygous hAHR, Ahr^b-1/b-1, and Ahr^d/d fetuses

Genotype of fetuses	TCDD dose, μg/kg	Dams examined, n	Fetuses examined, n	Fetuses with
				Cleft palate		Hydronephrosis
				n	%*	n	%*	Severity: 0–3.0†
Ahrb-1/b-1	0	2	13	0	0	2	12.5	0.19  ± 0.10‡
Ahrb-1/b-1	40	5	29	29	100	26	89.7	2.54  ± 0.14§
Ahrd/d	0	2	15	0	0	2	13.3	0.20  ± 0.10‡
Ahrd/d	40	5	30	9	30	25	81.7	1.98  ± 0.14§
Homo-hAHR	0	2	16	0	0	1	6.3	0.03  ± 0.03‡
Homo-hAHR	40	5	37	0	0	30	81.1	1.19  ± 0.01§

^*Percentage of fetuses with each anomaly of all fetuses examined. 

^† The criteria for severity scores are described in Materials and Methods. Data are expressed as mean ± SE. 

^‡ Significant difference between TCDD-treated and -untreated fetuses of each genotype (P < 0.0001). 

^§ Significant difference between TCDD-treated homozygous hAHR fetuses and Ahr^b-1/b-1 or Ahr^d/d fetuses (P < 0.0001).