author(s)
Ritun Patra, Uma Kanta Mishra and Choudhury Deepak R Mohapatra

abstract
A study was designed to elucidate the gross morphological development of rumen of sheep during pre-natal life. For this study 12 foeti were divided into three groups i.e. Group I (0-50 days of pregnancy), Group II (51-100 days of pregnancy) and Group III (101-150 days of pregnancy) with 04 foeti in each group. The developing rumen appeared to have a left and a right ruminal bud together assuming the quadrilateral shape at the age between 32 and 44 days of gestation. The whole rumen appeared as a sac like structure with a slight caudo-ventral projection at 63 days of gestation. Between 63 and 94 days of gestation, the rumen was seen to be attached with septum transversarium dorsally. During this period the parietal surface was related to the developing pancreas and left adrenal gland. The visceral surface was related to the coils of the intestine. At 150 days of gestation, the visceral surface of dorsal sac was adjacent to the developing abomasum. The developing rumen was noted to extend from 8^th rib to 1^st lumbar at 150 days of gestation. The cranial and caudal transverse grooves appeared at 32 and 48 days of gestation respectively. The right and left longitudinal grooves appeared at 48 and 94 days of gestation respectively. The internal surface of rumen revealed cranial and caudal pillars at 32 and 63 days of gestation respectively. By 116 days of gestation, small conical papillae were grossly seen to project into the lumen giving the internal surface a rough appearance. The scanning electron microscopic observations revealed appearance of ruminal papillae of very small size at 44 days of gestation. These papillae gradually became tall and appeared as distinct projections from 63 days of gestation and onwards.