TABLE 1

Mean ± S.D. total body and liver weights (grams) and hepatic microsomal protein content (milligrams per gram of liver) for male Sprague-Dawley rats (n = 4) at different pre- and postnatal ages

Significant life stages in relation to age groups reported in the table are average gestation period, 22 days; weaning, 21-28 days; puberty, 42-63 days; and adult, 112 days (life stage information provided by Charles River Canada).

Age	Total Body Wt.	Liver Wt.	Microsomal Protein
	g			mg/g liver
Fetus^a	2.69 (0.58)^b	0.21 (0.055)^b	5.71 (2.3)^b
1 day	7.09 (0.46)^b	0.32 (0.077)^b	9.40 (3.2)^b
3 days	9.40 (0.82)^b	0.42 (0.070)^b	14.7 (3.8)^b
5 days	12.9 (1.4)^b	0.53 (0.096)^b	15.7 (6.8)^b
7 days	17.4 (1.3)^b	0.63 (0.089)^b	20.6 (4.0)
10 days	26.2 (4.3)^b	0.86 (0.34)^b	22.3 (4.4)
14 days	32.7 (3.1)^b	1.13 (0.24)^b	27.3 (4.7)
21 days	59.4 (4.8)^b	2.62 (0.24)^b	36.4 (14.1)
28 days	105 (6.3)^b	4.93 (0.54)^b	39.2 (14.0)
42 days	203 (12.1)^b	9.39 (0.75)^b	43.1 (15.3)
63 days	399 (30.5)^b	16.2 (2.6)	36.0 (10.9)
84 days	411 (9.6)^b	13.8 (0.51)	41.3 (6.9)
112 days	507 (27.3)	15.0 (1.4)	32.4 (7.3)

↵ a Fetuses were collected at 20 days gestation from three dams and the fetal livers obtained from a single dam were pooled for microsomal preparation.
↵ b Statistically significant from adult (112 days); P < 0.05.