The Number of Grafted Fragments Affects the Outcome of Testis Tissue Xenografting from Piglets into Recipient Mice

Table 1

Characterization of testis tissue xenografts recovered from recipient mice at 8 months postgrafting.

	Number of testis tissue fragments grafted (per mouse)
	2	4	8	16
Number of mice analyzed*	8	10	9	10
Mouse body weight (g)	29±0.5	29±1.5	30±0.6	32±0.9
Graft recovery rate (%)	86±9.2	98±2.5	90±8.7	95±3.8
Average graft weight (mg)	106±38.0^a	196±25.5^ab	208±36.6^ab	278±39.4^b
Total graft weight (mg)	192±76.2^a	704±82.2^a	1,619±289.9^b	2,443±338.8^b
Vesicular gland index (%)	0.1±0.06^a	0.3±0.06^ab	0.3±0.05^ab	0.5±0.06^b
Vesicular gland weight (mg)	35±16.7^a	84±16.1^ab	94±18.3^ab	154±21.9^b
Tubular diameter (𝜇m)	126±18.2	121±14.7	141±9.1	144±2.6
Tubular density (/mm^2)	31±6.4	39±3.4	38±3.1	32±1.6
Spermatozoa (% of tubules)	17±7.5	23±6.3	26±6.1	28±3.2
Elongated spermatids (% of tubules)	4±1.9	10±2.0	8±2.1	11±1.6
Round spermatids (% of tubules)	3±1.3^b	8±2.2^ab	8±1.9^ab	11±1.5^a
Spermatocytes (% of tubules)	4±2.4	16±3.4	13±2.3	12±2.7
Spermatogonia (% of tubules)	4±1.9	5±1.4	4±1.6	3±2.4
Sertoli-cell only (% of tubules)	42±8.8	28±6.4	29±6.9	21±3.0
Degenerated (% of tubules)	27±5.7^a	11±3.3^b	12±1.6^b	14±2.6^ab

Four groups of recipient mice were grafted with different numbers of porcine testis tissue fragments, and the xenografts were evaluated at 8 months postgrafting for spermatogenic development. Recipient mice were gonadectomized male nude mice and randomly assigned into groups receiving 2, 4, 8, or 16 testis tissue fragments per mouse (𝑛=10 mice/group). ^∗The number of recipient mice per group that survived to the time of analysis at 8 months postgrafting (the original number was 10 mice per group). Graft recovery rate was defined as the relative number of visible xenografts retrieved compared with the number of fragments grafted. The average graft weight and histological evaluations were based on the recovered grafts. The average seminiferous tubule diameter and tubular density (the number of the seminiferous tubules/mm²) were calculated in the largest cross section of the recovered grafts. For comparison, at the time of grafting, the donor tissue had seminiferous cords that were 47±1.1 𝜇m in diameter and at a density of 95±6.1 tubules/mm². Data are presented as mean ± SEM. ^abValues with different superscript letters within each row are significantly different (𝑃<.05).