Abstract

The rectal malformations are the most frequent and severe birth defects present in newborn animals. Many aspects of adult intestinal disease have an underlying developmental basis. The study was conducted to observe the sequential developmental changes of the rectum from its primordial stage till parturition. For this purpose, thirty-six (n=36) animals were used. The gross, histological, and histochemical examinations were performed on the rectum of the goat. The first morphological evidence of the rectum was notified on the 45^th day of gestation. The rectal epithelium was transformed from stratified to simple columnar at the 75^th day of gestation. The presence of rectal pits might be used for the identification of different segments of the large intestine in intrauterine life as well as to correlate it with pellet morphology in goats. The study uncovered a unique feature, the presence of villi in the rectum at 58^th and complete degeneration up to150^th days of fetal development. Among the connective tissue fibers, the reticular fibers appeared earliest followed by collagen and elastic fibers. The rectum showed an intense reaction for alkaline phosphatase, PAS, and AMPs.

Keywords:Histogenesis; Intestine; Ontogeny; Prenatal; Rectum