Histomorphological study of the pre hatching development of the female genital system in Indigenous Mallard Duck (Anas platyrhynchos)

The current study is endeavored and intended to obtain principal data on the histomorphological developmental changes in the female genital system of Mallard ducks in Iraq. Twenty females of Mallard ducks are used to monitor the embryonic changes may occurs during the following pre-hatching periods: 7-8th, 14th and 19th day. Results revealed that the intermediate cell mass of mesoderm is the primordia of the reproductive organs and their ducts. Gonads are developed at the median face of the mesonephros. Paramesonephric duct of mesonephros undergoes morphological changes ended by oviduct formation which derived from the peritoneal covering of mesonephros subsequently converted into urogenital ridge. In 7-8th day old embryo, the left and right ovaries revealed undistinguished cortex and medulla, whereas in 14th day old embryo, the left ovary is significantly enlarged, whereas, the right is small and rudimentary. At the anterior region of urogenital ridge both oviducts are observed, but the left is completely fused tube and invaded the tissue of the left mesonephros, while right tubal ridge remain not fused yet. In middle region of the ridge the left and right tubal ridges are fused. In caudal region of the ridge, the left and right tubal ridges are still not fused and they attached to the lateral border of the left and right metanephros. In 19th day old embryo, the left ovary is extensively enlarged with obvious tunica albuginea separating cortex from the medulla. In this period an important developmental changes are recognized in the regions of the oviduct.