Cervical lymph nodes and mast cells in the marsupial Sminthopsis crassicaudata

Abstract

A study of the cervical lymph nodes from the fat-tailed dunnart, Smithopsis crassicaudata, revealed the nodes were pigmented with lipofuscin and contained many large cells which were identified as mast cells from their ultrastructure and histochemical staining properties. It is believed that the very high density of mast cells in the cervical lymph nodes contributed to an increase in size of these organs compared to other animals. Very high levels of histamine (90 micrograms/g) were found in the nodes. Cervical lymph nodes with these unusual features were found not only in healthy, umprimed laboratory bred adults, but also in pouch young, wild caught animals, and adults of the closely related species, Sminthopsis macroura. A comparison of the histochemical and ultrastructural characteristics of mast cells from various organs of adult S. crassicaudata was also made. Mast cells from lymph node, skin, tongue, salivary glands, intestinal mucosa, and spleen showed slight variations in staining and structure.