Immortalized Sertoli cell lines sk11 and sk9 and binding of spermatids in vitro.

AIM To determine the effectiveness of the sk11, sk9 and sk11 TNUA5 Sertoli cell lines in binding germ cells in vitro. METHODS The immortalized Sertoli cell lines sk9, sk11 and sk11 TNUA5 were used in co-culture experiments with germ cells in media with or without reproductive hormones and incubated for 44 h at 32 degrees . The number of germ cells bound to Sertoli cells was then determined and statistically analyzed. Western blot analysis and reverse transcriptase-polymerase chain reaction (RT-PCR) studies were employed to investigate the presence of cell adhesion proteins and follicle stimulating hormone (FSH) receptor, respectively. RESULTS No statistical difference between the number of bound step-8 spermatids and bound pre-step 8 spermatids on Sertoli cells from any of the cell lines existed. After the addition of germ cells, Sertoli cells showed more lipid accumulation in their cytoplasm, indicating active phagocytosis. Western blot analysis in the sk11 TNUA5 line indicated the expression of N-cadherin. FSH-only and testosterone-only treatments increased N-cadherin expression, regardless of germ cell addition. The addition of germ cells to the sk11 TNUA5 Sertoli cells increased the expression of espin, as did the addition of FSH with germ cells. RT-PCR studies of the sk11 TNUA5 cells indicated that the mRNA for FSH receptor decreased with successive passages. CONCLUSION In vitro binding between isolated germ cells and sk9, sk11 or sk11 TNUA5 Sertoli cells is not feasible, and therefore these cell lines are not useful for the in vitro investigation of Sertoli-germ cell interactions and primary Sertoli cell isolates must still be used.