The effects of four- to eight-week complete parenteral nutrition on the digestive tract were studied in puppies 8 to 10 weeks old. In these animals, the development of the gastrointestinal tract was markedly disturbed with a reduction in length, weight, and thickness of all intestinal layers. On the other hand, the microscopical structures were well preserved. There was no noticeable difference between the experimental and the control animals in the gastric pitgland ratio, the villus-crypt ratio, and the cellular component, the content of PAS-positive substance and the distribution of sudanophilic fat in the mucosal membrane, although a reduction in the mitotic index in the jejunal crypt was seen in the experimental animals.
Koga Y, Ikeda K, Inokuchi K, Watanabe H, Hashimoto N. The Digestive Tract in Total Parenteral Nutrition. Arch Surg. 1975;110(6):742-745. doi:10.1001/archsurg.1975.01360120060011