Unique crystalline inclusions in neonatal pig small intestine epithelial cells

In this study we describe the presence of novel crystalline inclusions in the jejunal and ileal epithelium of newborn pigs. Hampshire/Yorkshire piglets (0-3 days) were anesthetized with pentobarbital and tissues were recovered following laparotomy. Sections of jejunum and ileum were prepared with a variety of fixatives for paraffin and methacrylate embedment for the light and electron microscopy. The characteristics of these crystalline structures have been demonstrated by cytochemical staining, immunohistochemical staining, and ultrastructural studies. Using light microscopy, it was determined that 10.8% of villus epithelial cells in the jejunum contained inclusions, whereas inclusions were present in 26.6% of the villus epithelial cells in the ileum. Inclusions were absent in crypt epithelial cells of both areas of the intestine, and the percentage of cells with inclusions increased towards the villus tip. Preliminary histochemical analysis has been unrevealing. The inclusions are periodic acid/Schiff's (PAS) reagent-negative, and do not stain for the presence of concentrated proteins. Using electron microscopy, the inclusions are found to be clustered in the supra-nuclear region of the cells and are generally oriented with the long axis of the cell. The crystals vary in size and have a dense core region surrounded by a regular less dense periphery.