In the mouse, Sryis expressed by somatic cells in the genital ridge and leads to initiate the transformation of the indifferent gonad into a testis. Here, we have examined the segmented female and male mesonephroi over the developmental period when the initiation of seminiferous cord formation takes place. We have generated three-dimensional models which reveal structural differences between male and female mesonephric tubules at 11.5, 13.5 and 14.5 days post coitum. We evaluate, following

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... tural parameters, that form and orientation of the tubules could evolve differently in both sexes. We propose that the structural organization of the mesonephric tubules presents an early dimorphism.