Small intestine
It is approximately 1.5 cm in diameter in newborns after 35 weeks of gestational age, and 2.5–3 cm (1 inch) in diameter in adults. On abdominal X-rays, the small intestine is considered to be abnormally dilated when the diameter exceeds 3 cm. On CT scans, a diameter of over 2.5 cm is considered abnormally dilated. The surface area of the human small intestinal mucosa, due to enlargement caused by folds, villi and microvilli, averages 30 square meters.
Gastrodiscoides
It is a large fluke, vase-shaped, and bright-pink in colour. In average it measures 5–8 mm long and 3–5 mm wide. The disc-shaped body is divisible into anterior conical and posterior discoidal regions. The anterior region is a conical projection bearing a prominent oral sucker. The posterior portion is relatively broad, up to 8 mm wide, discoidal, and ventrally excavated. It is an amphistome worm such that the ventral sucker is close to the posterior end. The body covering, called a tegument, is smooth in appearance, but contains a fine structure in a series of concentric folds bearing numerous tightly packed tubercles. Ventral surface contains a specialised region of the tegument. Ciliated and non-ciliated papillae are arranged around the oral sucker. The incomplete alimentary canal consists of a pair of lateral pouches arising from the oral sucker and a slightly tortuous pharyngeal tube, which bifurcates into two gut cæca. The large excretory bladder is in the middle, behind the ventral sucker. The species, being hermaphrodite, has both male and female reproductive systems, arranged in the posterior region. The testes lie in alongside the bifurcation of the cæca, and a common genital pore is on the cone just anterior to the bifurcation. The oval-shaped ovary lies just posterior to the testes in the middle, and the loosely coiled uterus opens to the genital pore. Vitelline glands are scattered around the cæca.