Table 1.

Incidence of tumor formation in organs in nude rats over 460 days after knee joint surface defects were implanted with HeLa cells.

Sex	M	M	M	M	F	F	F	F
Number of HeLa cells implanted	1 × 105	1 × 104	1 × 103	1 × 102	1 × 105	1 × 104	1 × 103	1 × 102
Number of rats
Total	4	4	4	4	4	4	4	4
Dead before day 460	0	1**	0	0	0	1	1*	0
Euthanized before day 460 due to knee tumor	3	0	0	0	3	0	0	0
Number of organs with tumors
Liver	0	0	0	0	0	0	0	0
Lung	0	0	0	0	0	0	0	0
Kidney	0	0	0	0	0	0	0	0
Spleen	0	0	0	0	0	0	0	0
Heart	0	0	0	0	0	0	0	0
Brain	0	0	0	0	0	0	0	0
Lymph node	0	0	0	0	0	1	0	0
Pituitary	0	0	0	0	0	0	0	0
Knee	3	0	0	0	3	0	0	0
Subcutaneous	0	0	0	0	0	0	0	0
Testis	0	0	0	0	–	–	–	–

*Brain contusion.

**Cerebral infarction.