Faculty of Veterinary Medicine, Urmia University Veterinary Research Forum 2008-8140 7 1 2016 03 01 Developmental study of rectum in broiler chicken: A stereological and morphometrical study 41 45 19037 EN Rahmat-Allah Fatahian Dehkordi Department of Basic Sciences, Faculty of Veterinary Medicine, Shahrekord University, Shahrekord, Iran 0000-0003-2126-6847 Poria Ghahremani DVM Student, Faculty of Veterinary Medicine, Shahrekord University, Shahrekord, Iran Journal Article 2016 03 14 The objective of this study was to investigate development of the weight and the morphological development of the rectum in broiler chickens. Twenty broiler chickens (Ross 308) were used in this experiment and they were 12, 20, 35 and 44 days of age. Samples from the rectum of chicks were sectioned in an unbiased manner and examined quantitatively using stereology. In addition, the weight of both body (BW) and rectum and also rectum weight as a proportion of BW, height and width of the villi and thickness of rectum wall were measured. The results revealed that the body and rectum weight were increased with age. The greatest rectum weight as a proportion of BW was observed on day 20. An increase in height and width of the villi during the study period were obtained. The increase was more significant on days 35 and 44 than on days 12 and 20 (<em>p</em> < 0.05). There were significant difference in thickness of tunica mucosa, submucosa and muscular layer of the rectum on day 20 compared to day 35 (<em>p</em> < 0.05). The increase in the volume density of the wall, tunica mucosa and tunica muscular was greater on day 20 than on day 35. However, significant differences were observed in volume density of this layers between days 35 and 44 compared to days 12 and 20 (<em>p</em> < 0.05). https://vrf.iranjournals.ir/article_19037_7278d0d386dcc62e9c1bd86449fd41de.pdf