Prenatal HgCl₂ Exposure Alters Fetal Cell Phenotypes

Figures & data

TABLE 1 Litter statistics from two independent experiments evaluating the effects of intrauterine exposure to 10 ppm HgCl₂

	Experiment 1					Experiment 2
	Control		Mercury			Control			Mercury
Dam	D1	D2	D3	D4	D5	D1	D2	D3	D4	D5	D6
Number of male pups	2	0	3	3	5	0	4	3	3	3	2
Number of female pups	9	6	1	6	1	2	2	3	3	4	4
Number of fetal resorptions	0	0	2	1	0	0	0	0	0	0	0
Average pup body weight (g ± SD)	0.85 ± 0.24 (range 0.60–1.28)		0.82 ± 0.26 (range 0.58–1.24)			1.04 ± 0.14 (range 0.85–1.22)			0.90 ± 0.28 (range 0.53–1.19)
Total litters	5					6
Total number of pups	36					33

(BALB/c × DBA/1)F₁ (DBF₁) fetuses were extracted on gd 16. All pups in each litter, excluding resorbed fetuses, were used in immunophenotyping.

FIG. 1 Enumeration of (A) total and (B) fetal body weight-adjusted thymic cell counts of gestational day 16 fetus pooled from 2 independent timed-breeding experiments.

TABLE 2 Effects of intrauterine exposure to 10 ppm HgCl₂ on CD4/8-expressing gd 16 cells in the thymus

	CD4^+CD8^−	CD8^+CD4^−	DP	DN
A
Control Male	8.78 ± 2.41	16.26 ± 4.07	1.91 ± 0.58	73.05 ± 4.51
Mercury Male	7.29 ± 2.68	8.15 ± 1.89	0.84 ± 0.22	83.72 ± 2.78
Control Female	6.21 ± 1.27	12.59 ± 3.34	1.23 ± 0.45	78.96 ± 4.34
Mercury Female	5.68 ± 2.25	6.19 ± 2.72	0.55 ± 0.28	87.56 ± 5.03
B
Control Male	17.54 ± 6.29	31.68 ± 9.24	3.73 ± 1.34	144.97 ± 36.95
Mercury Male	11.98 ± 2.65	14.23 ± 4.78	1.41 ± 0.29	145.30 ± 28.41
Control Female	8.54 ± 5.23	21.06 ± 8.90	2.14 ± 1.11	130.33 ± 37.93
Mercury Female	8.40 ± 3.83	9.19 ± 4.47	0.79 ± 0.45	138.75 ± 54.69

(A) Percentages and (B) total cell counts (×10⁵ cells) in each compartment were determined by flow cytometry and expressed as mean ± SD. Data gathered from a single timed-breeding experiment of 14 control pups and 19 mercury-exposed pups. A repeat timed-breeding experiment showed similar results. * p < 0.05 level of significance.

TABLE 3 Effects of intrauterine exposure to 10 ppm HgCl₂ on CD25 expression of gd 16 thymic cells

	CD4^+25^+
	% lymphocytes	Absolute number (×10^5 cells)
Control Male	26.05 ± 3.73	5.06 ± 0.90
Mercury Male	12.74 ± 3.83	2.23 ± 0.85
Control Female	23.56 ± 9.10	3.90 ± 2.02
Mercury Female	13.45 ± 4.73	2.19 ± 1.17

Percentages and total cell counts in each compartment were determined by flow cytometry and expressed as mean ± SD. Data gathered from a single timed-breeding experiment of 14 control pups and 19 mercury-exposed pups. A repeat timed-breeding experiment showed similar results. * p < 0.05 level of significance.

FIG. 2 Effect of intrauterine exposure to 10 ppm HgCl₂ on B220 expression in liver of gd 16 mice measured as mean fluorescence intensity. Dashed line refers to male-mercury-exposed pups; solid line refers to female mercury-exposed pups. Data is representative of two independent timed-breeding experiments.

TABLE 4 Effects of intrauterine exposure to 10 ppm HgCl₂ on Id^LNF₁-reactivity in gd 16 (A) thymus and (B) liver

	% lymphocytes	Absolute number (×10^5cells)
	A
	CD4^+Id^LNF1^+
Control	0.87 ± 0.59	0.64 ± 0.11
Mercury	2.06 ± 1.05	0.36 ± 0.24
	B
	Id^LNF1^+/B220^+/CD3^−
Control	44.47 ± 12.93	4.86 ± 4.98
Mercury	62.28 ± 10.83	7.04 ± 6.51

Percentages and total cell counts in each compartment were determined by flow cytometry and expressed as mean ± SD. Data gathered from a single timed-breeding experiment of 14 control pups and 19 mercury-exposed pups. A repeat timed-breeding experiment showed similar results. * p < 0.05 level of significance.