S.R Ghazi - Department of Anatomy, School of Veterinary Medicine, Shiraz University , Shiraz - Iran
S Gholami - Department of Anatomy, School of Veterinary Medicine, Shiraz University , Shiraz - Iran

The study was conducted on fetuses in 3 , 4 and 5 months of gestation, newly born lambs up to one month age and adult Iranialll sheep of Mehraban breed up to 4 years old. All the 5 groups contained 6 animals in each group. The trend of variation~!il in the total length of vertebral column by aging as well as the trend of regional and segmental developmental changes were observed. The total length ofvertebral column was 202.8± 16.19 nun in 3 month fetus, 294±22.8~• nun in 4 month fetus, 405.2±37.28 nun in 5 months fetus, 566.3±30.61 nun in newly born lamb and 1054±87.~~7 nun in adult sheep. The lenght of thoracic m vertebral column was maximum in the animals of all age groups followed by cervical (C), lumbar (L), coccygeal (Co) and sacral1[S) ones, execpt in 5 months fetus where thelenght of coccygeal vertebral column was longer than that of the lumbcll' region. These results further indicated that in the cervical region, C2 vertebra was the longest and C1 the shortest in all the age groups. In thoracic region, T1 was longest in 3. and 4 months fetuses, whereas in rest of the animals T 13 was longest. The shortest vertebrae in this region were: T7 , Tg , Ts and T6 in 3 , 4 and 5 monthsfetuses, resJPectively, and T7 in newly born lamb and adult sheep. In lwnbar region L6 vertebra was longest in most of the age groups except in adult sheep where Ls was longest. In addition to 4 , L4 and Ls were also long in 3 months fetus. However, the shortest vertebra was L1 in all stages. In sacral re!lrion, S1 vertebra was longest in all age groups, whereas S4 was shortest except in adult sheep where ~was shortest.

developmental trend. vertebral colUilUl, pre - and postnatal life, sheep