Studies on testicular histology of transgender patients. The 13 publications that analyzed testicular histology (n = 680) of transgender patients. In brackets are the total numbers of testicular tissues assessed in the respective publications. Rodrigues-Rigau et al. (1; 1977) [37], Lu et al. (4; 1978) [38], Payer et al. (6, 1979) [39], Thiagaraj et al. (10; 1987) [40], Venizelos et al. (5; 1987) [41], Sapino et al. (5; 1987) [42], Schulze et al. (11; 1988) [43], Kisman et al. (8; 1990) [44], Lübbert et al. (1; 1992) [45], Aschim et al. (3; 2004) [46], Matoso et al. (99; 2018) [21], Jindarak et al. (178; 2018) [22], Schneider et al. is an update of a previous study.