Table 3.

Damage to seminiferous tubules of C57BL/6 and AKR/N mice after heat treatment^a

Strain	Time Post–Heat Treatment, h	% Tubules With 0–2 Positive Cells/Tubule	% Tubules With 3–5 Positive Cells/Tubule	% Tubules With >5 Positive Cells/Tubule
C57BL/6	8	63.5 ± 5.1	2.2 ± 0.7	35.2 ± 2.8
	10	5.0 ± 1.0	13.2 ± 2.5	82.3 ± 2.9
	12	0 ± 0	8.2 ± 1.0	91.4 ± 1.2
	24	0 ± 0	0 ± 0.02	99.9 ± 0.1
	No heat treatment	97.8 ± 1.6	2.2 ± 1.0	0 ± 0.5
AKR/N	8	98.4 ± 1.8	1.4 ± 0.9	0.9 ± 0.1
	10	72.2 ± 2.1	5.9 ± 0.3	23.6 ± 3.8
	12	35.1 ± 5.3	6.2 ± 2.0	61.1 ± 3.2
	24	31.2 ± 6.1	4.3 ± 1.1	62.5 ± 4.6
	No heat treatment	99.2 ± 0.08	0.2 ± 0.05	0.6 ± 0.1

^aAll genes must have a raw signal no less than 50 in at least 1 strain and 2-fold or more differences in expression between C57BL/6 and the other 2 strains. Tubules with only 0–2 positive cell(s) were considered normal, whereas tubules with more than 5 positive cells were considered damaged. In C57BL/6, damaged tubules increased dramatically at 8 and 10 h after exposure to heat. After 24 h, all tubules showed signs of damage. In contrast, the damage was delayed in AKR/N and even after 24 h, about 30% of the tubules showed no sign of germ cell loss.