STAGE-SPECIFIC EXPRESSION OF THE FSH RECEPTOR GENE IN THE PREPUBERTALAND ADULT-RAT SEMINIFEROUS EPITHELIUM

Stage-specific expression of the FSH receptor (FSHR) gene in the rat s eminiferous epithelium was studied. Using transillumination-assisted m icrodissection for sample preparation and Northern hybridization for a nalysis of total RNA, we first reassessed the stage specificity of the FSHR gene expression in the adult rat testis. Sixfold higher FSHR mRN A levels were found in stages XIII-I compared with stage VI of the sem iniferous epithelial cycle, which had the lowest signal level (P<0.01) . The other stages had intermediate signal levels. In situ hybridizati on showed distribution of grains which confirmed the data obtained by Northern analysis. Prepubertal stage-specific FSHR gene expression was studied using in situ hybridization. Stage specificity could first be demonstrated at pe age of 16 days when the average grain counts in st ages I-IV were threefold higher than in stages VI-VII (P<0.01). The pr esent data are in agreement with earlier findings on stage-specific FS H binding and FSHR gene expression using both microdissected and stage -synchronized seminiferous tubules. The onset of stage-specific FSHR g ene expression is concomitant with maturation of the Sertoli cell popu lation and completion of the first generation of spermatocytes. This s upports the hypothesis that spermatogonia and spermatocytes may be inv olved in the regulation of FSHR gene expression.