( !)!** +!)+$%""! !! +! "!!

The early development of the two Müllerian (paramesonephric) ducts is identical in both sexes. At day seven they reach the cloaca with the compact distal end, but there is no opening into the cloaca prior to hatching. An occluding plate between oviduct and cloaca even persists up to the first breeding season (from Gilbert, 1979). In the male embryo, both Müllerian ducts, and in the female embryo, the right Müllerian duct undergos regression starting at the eighth day of development. According to Lutz-Ostertag (1954) the regression of the male duct occurs in two phases: first, the epithelium undergoes cell death; and second, the ducts are transformed into dense mesenchyme.