Mast cell types and cell-to-cell interactions in lymph nodes of the opossum Didelphis albiventris

Abstract

Previous light-microscopic studies have shown a unique population of mast cells in lymphatic sinuses of lymph nodes located in the head, neck, axillary fossa and inguinal region of the opossum. In the present work, scanning and transmission electron-microscopic studies in the opossum mandibular and superficial axillary lymph nodes have strengthened the differences between connective-tissue mast cells (CTMC) and the lymphatic-sinus mast cells (LSMC). Further, close appositions of mast cells to other cells were described. At the nodal capsule, CTMC contacted fibroblast and granulocytes. In the lymphatic sinuses a few CTMC contacted LSMC, macrophages and reticular cells. The LSMC contacted macrophages, reticular cells and other LSMC. A few LSMC could be located in the medullary cord in close contact with plasma cells or other lymphoid cells, keeping the same ultrastructural features of those found in the lymphatic sinuses. An important new finding was provided by light-microscopic studies in nine abdominal lymph nodes. Most of them (para-aortic, common iliac, cardial, cecocolic and those of the body and tail of the pancreas) displayed numerous LSMC with the same distribution and histological features described herein. However, the mesenteric, pyloric and head-of-pancreas lymph nodes were virtually devoid of LSMC. Instead, their mast cells occurred mainly at the medullary cords and were very similar to the CTMC. Ultrastructural studies at the mesenteric lymph nodes confirmed the CTMC character of the mast cells located at both medullary cords and sinuses, and disclosed interactions with macrophages and lymphoid cells.

Ultrastructural Changes in the Uterine Luminal and Glandular Epithelium during the Oestrous Cycle of the Marsupial <i>Monodelphis domestica</i> (Grey Short-Tailed Opossum)

“…Mast cells have recently been described in marsupials, especially in Didelphis, but only in lymph nodes, intestine and skin, not in the genital tract [Haynes, 1991;Santos and Machado, 1994;Chiarini-Garcia and Pereira, 1999;Chiarini-Garcia et al, 2000]. Mast cells staining metachromatically with toluidine blue were noted in the uterus of the marsupial Bettongia by Tyndale-Biscoe [1968].…”

A Histological and Immunohistochemical Analysis of Lymphoid Tissues of the Tasmanian Devil

“…Abundance of mast cells in the lymph nodes has been described in a Dasyurid, the fattailed dunnart (Smithopsis crassicaudata), and in five Didelphidae marsupials. These mast cells were restricted to the lymphatic sinuses, contained large cytoplasmic granules and were thought to be of a different type from the connective tissue and mucosal mast cell populations (Haynes, 1991;Chiarini-Garcia and Pereira, 1999;Chiarini-Garcia et al, 2000). The medullary sinuses of the devils lymph nodes enclosed large numbers of toluidine blue positive cells, morphologically consistent with mast cells.…”

Ultrastructural Changes in the Cervical Epithelium during the Estrous Cycle of the Marsupial <i>Monodelphis domestica</i> (Grey Short-Tailed Opossum)

“…Mast cells, which are regarded as immunoregulatory cells [Metcalfe et al, 1997], have recently been described in marsupials, especially in Didelphis but only for lymph nodes, intestine and skin and not for the genital tract [Haynes, 1991;Santos and Machado, 1994;Chiarini-Garcia and Pereira, 1999;Chiarini-Garcia et al, 2000]. Mast cells staining metachromatically with toluidine blue have been mentioned in the uterus of the marsupial Bettongia by Tyndale-Biscoe [1968].…”