Histological features of the spleen and pancreas of the Egyptian Nile monitor lizard (Varanus niloticus)

Abstract

The present study investigated the histological features of the spleen and pancreas of the Egyptian Nile monitor lizard (Varanus niloticus). After gross observations the representative samples were collected from three adult male monitor lizards and were processed for histological examination. Grossly, the spleen was brownish in color and embedded in the mesentery near the stomach and pancreas. The pancreas was yellowish in color and consisted of a ventrally placed principal lobe which was pyramidal and extended in the mesentery, whereas the dorsally located splenic lobe was small and was attached to the spleen. a single duct was emerged from the pancreas. Histologically, the spleen was nodular and was encapsulated by the connective tissue capsule covered by mesothelium. it was composed of white and red pulps. Many ellipsoids, melano-macrophage centers, periarterial and periellipsoidal lymphatic sheaths (PALS and PELS; respectively) were observed. The pancreas demonstrated a thicker capsule covered by mesothelium and the exocrine portion was formed of tubule-acinar cells. Main pancreatic duct passed across the length of the pancreas and was lined by stratified cuboidal epithelium. The islets were found in the ventral lobe where it was in various sizes. This is the first report about the histological structure of the spleen and pancreas of the Egyptian Nile monitor lizard, where the spleen showed a unique structure while the pancreas was similar to what was described in other varanus species. The information in this study will be a baseline knowledge for future studies regarding endocrine or immune organs in this species.

Keywords

• melano-macrophages
• pancreas
• reptile
• spleen
• varanus.