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.
Anguina agrostis
The lip region is slightly offset (3-4 µm high) and the nematode has a very short stylet (10 µm). "A. agrostis" has a three-part esophagus. The procorpus is cylindrical with a swelling near its midsection. The metacorpus is ovoid in shape and the isthmus is long and narrow. The postcorpus has three glands and is highly developed, but does not overlap the intestine. On average, infective juveniles (J2) measure 530 µm and dauer juveniles measure 760 µm; the increase in size is due to feeding and the formation of lipid droplets or storage bodies. Females range from 1.5-2.7 mm in length, are curved ventrally, and are swollen. The vulva is located near the posterior end and one ovary is present. Males are smaller (1.1-1.7 mm in length), are not as swollen, and have a small bursae that extends subterminally. One testis is present.