We have successfully specified essential sequences of the 5' upstream region for the stage- and tissue-specific expression of mouse Sry by using an in vitro Cre/loxP system. Sry/Cre plasmids carrying Sty 5' sequences of various sizes were transfected into the primary cultured cells from different tissues of CAG/loxP/CAT/loxP/LacZ transgenic fetuses on 11.5-day post coitus (dpc) or 13.5-dpc. Stage- and tissue-specific regulation of Sty expression was disrupted by the deletion of positions 7549-7660 (from -0.4 to -0.5 kb region). In vitro transcription assay also suggested that the region contains element(s) responsible for stage- and tissue-specific expression of mouse Sty. SRY promoter of Shiba goat (Capra hircus var Shiba), a native Japanese miniature goat, showed the tissue-specific activity in the cells from urogenital ridges of the male mouse, but not in the cells from female mice, indicating a possibly different mechanism among species in the regulation of Sry expression. (c) 2005 Elsevier Inc. All rights reserved.