Figure 3. Potential clinical applications of the spermatogonial stem cell transplantation. A) (C) M037, which exhibited successful transplant engraftment based on presence of sperm in the ejaculate, (D) transplant recipient M214 which never exhibited sperm in the ejaculate after transplant, (E) Histology from the testis and epididymis of an un-transplanted animal M104 illustrates the appearance of an azoospermic (empty) testis after busulfan treatment (Hermann et al., 2012). B) Immunohistochemistry of host testes after transplantation and organ culture. Expression of specifc proteins of spermatogonial cells (PLZF), spermatocytes (SCP3) and spermatozoa (ACRBP) and detection of DiI in host testes after 8 weeks of tissue culture (Mohaqiq et al., 2019a).