Study of the process of development of stomach in the ovine fetus

This study was carried out to determine the process of formation, development and topographic characteristics of different parts of stomach and extent of their rotation in sheep fetuses. For this purpose, 14 ovine fetuses at the age of 38,40,45,47,52,58,66, 75, 80,88,103,110,130 and 150 days of gestation were examined. The uteri of 50 pregnant ewes were collected from the abattoir and after determination of the age of the fetuses, they were fixed in 10% buffered formalin solution and following necropsy, the topography of stomach was studied. At 30-day of gestation, the omasum was seen opposite the reticulum and results indicated that its development takes place along the vertical axis. At 38 days rumen was the largest part of the stomach situated cranial to reticulum, while at 47 days of gestation, the size of rumen and reticulum was approximately equal. The enlarged rumen moves caudally and the reticulum moves forward from underneath the rumen at about 52 days of gestation. At 66 days, rumen was the largest chamber in comparison to other parts of the stomach and the reticulum was located completely in front of the other parts. The abomasum was massive at 103 days and it was the largest part of stomach at 110 days of gestation. The results indicated that at the beginning of the developmental process, the rumen is situated cranially and abomasum caudally. Gradually as the rumen enlarges it migrates dorsal and caudal to the abomasum. Finally, the reticulum moves forward underneath the rumen and forms the most cranial part of the stomach.