Table 1.

Spermatogenesis from cultured spermatogonial stem cells following transplantation to recipient seminiferous tubules

Experiment	Age of testes	Days cells in culture (passages)	Presence of STO feeders†	Concentration of cells/ml injected (× 106)	Number of testes injected	Number of testes colonized‡	Number of tubules with donor Spermatogenesis§
							Right	Left
1	7 weeks	19 (0)	+	8	2	2	12+	12+
2	6 weeks	10 (0)	—	28	6	0	—	—
3	6 weeks	22 (0)	—	35	6	0	—	—
4	7 weeks	19 (0)	—	51	8	0	—	—
5	8 days*	25 (0)	+	13	1	1	12+	—
6	10 days	111 (1)	+	6	2	2	4	12+
		132 (2)	+	5	2	0	—	—
7	11 days	62 (1)	+	7	2	1	5	0
		62(1)	—	5	2	0	—	—
		76 (2)	+	4	2	0	—	—
		99 (3)	+	2	2	0	—	—
		99 (3)	—	6	2	0	—	—

^*Accuracy ± 3.

^†+ indicates testis cells were cultured on a feeder layer of mitomycin-treated STO cells. When cells were injected into the seminiferous tubules, the mixed population of cells in culture was digested and used for transplantation.

^‡Number of testes with areas of cultured cell-derived spermatogenesis.

^§Number of tubules in recipient testis with cultured donor cell-derived spermatogenesis. Individual tubules that stained blue were counted up to a maximum of 12. The number of tubules in testes with greater than 12 stained could not be accurately counted because of intermingling of tubules, and these testes were designated 12+.