Anti-MIC2 as a tool in examination of testicular biopsies

MIC2 is a pseudoautosomal gene localized on X and Y chromosomes. The MIC2 g ene product is a glycoprotein expressed on the cell membranes of a number o f somatic cells, including Sertoli cells of the testis, but not on the cell membranes of germ cells. In cases of cryptorchidism, a testicular biopsy i s recommended in order to evaluate future fertility potential. The spermato gonia are identified on histological sections and the number per tubular tr ansverse section is compared with normal values for age. The patient is at 33-100% risk of subsequent infertility when the number of spermatogonia per tubular transverse section is lower than 1% of the lowest normal age-match ed value. Besides Sertoli cells the seminiferous tubules in undescended tes tes contain only a few germ cells, and it may be difficult to pinpoint the germ cells in small biopsies. Especially in nonpalpable testes their number may be heavily reduced. A reliable identification of germ cells may also b e difficult in cultures of testicular biopsies from undescended testes. Aga inst this background, we tried the use of an immunohistochemical method wit h DAKO antibody to the MIC2 gene product (MIC2, 12 E7, code no. M3601) in o rder to obtain a "negative reaction" of germ cells, contrasting with the st ained Sertoli cells. The material comprised: 44 specimens of testicular par enchyma taken at time of surgery for cryptorchidism from 24 cryptorchid boy s with nonpalpable testes and 14 testicular biopsies from 13 cryptorchid pa tients with palpable testes which had been cultured in vitro for 7, 14 or 2 1 days. In all cases the immunohistochemical method with DAKO antibody to t he MIC2 gene product was helpful for identification of Sertoli cells and ge rm cells, and we therefore recommend the use of anti-MIC2 in all testicular biopsies where it is difficult to pinpoint the germ cells.