Anatomy and nomenclature of murine lymph nodes: Descriptive study and nomenclatory standardization in BALB/cAnNCrl mice

Abstract

Murine lymph nodes are intensively studied but often assigned incorrectly in scientific papers. In BALB/cAnNCrl mice, we characterized a total of 22 different lymph nodes. Peripheral nodes were situated in the head and neck region (mandibular, accessory mandibular, superficial parotid, cranial deep cervical nodes), and at the forelimb (proper axillary, accessory axillary nodes) and hindlimb (subiliac, sciatic, popliteal nodes). Intrathoracic lymph nodes included the cranial mediastinal, tracheobronchal and caudal mediastinal nodes. Abdominal lymph nodes were associated with the gastrointestinal tract (gastric, pancreaticoduodenal, jejunal, colic, caudal mesenteric nodes) or were located along the major intra-abdominal blood vessels (renal, lumbar aortic, lateral iliac, medial iliac and external iliac nodes). Comparative and nomenclative aspects of murine lymph nodes are discussed. The position of the lymph nodes of BALB/cAnNCrl mice is summarized and illustrated in an anatomical chart containing proposals for both an official nomenclature according to the Nomina Anatomica Veterinaria and English terms.

Introduction

Rodents, and mice in particular, have long been used as laboratory animals in various scientific experiments. The possibility to produce different murine strains and a variety of knock-out mice, the high reproductive rate of these animals, and the ease of their handling have made them the preferential laboratory animal. In immunological sciences, murine lymph nodes (lnn.) are often used to isolate lymphocytes in order to study fundamental aspects of immunology and immunopathology. The methodology to recognize and dissect these lymph nodes requires at least a basic anatomical knowledge. In numerous studies, however, inaccurate, misleading or even enigmatic terms such as genital nodes (Cain and Rank, 1995) or tonsillar nodes (Deaglio et al., 1996) have sometimes been assigned to murine lymph nodes. The ambiguity of murine lymph node (ln.) nomenclature is illustrated by the lymph node at the ear base of mice which has been variably designated by various terms such as parotid ln. (Cuq, 1966, Grassé, 1972, Popesko et al., 1992), lateral mandibular ln. (Cuq, 1966), and facial ln. (Wolvers et al., 1999), while numerous recent studies refer to an allegedly auricular ln. (Anjuère et al., 1999, Dearman et al., 1996, Sailstad et al., 1995) or pre-auricular ln. (Hendrickx et al., 1992) in this region. Given this confusion, it becomes very difficult to reproduce the experimental reports or compare different scientific results. Nevertheless, the localization of the different lymph nodes with their respective names in mice has been thoroughly described in a number of anatomical publications (Barone et al., 1950, Cuq, 1966, Kawashima et al., 1964), but these papers are seldom referred to. A sample bibliographic (Medline) search from 1989 to 1999 demonstrated that of 293 randomly chosen papers in which the words “mouse lymph node(s)” are used, 89 citations (i.e. 30%) used only vague terms such as “lymph node”, “peripheral lymph node”, “draining lymph node”, “local lymph node”, or “regional lymph node” instead of the precise anatomical names. In the remaining 204 publications, at least 42 different specific names were given to the lymph nodes that were studied. Only 1 article, however, contained some figures illustrating the anatomical position and identification of the lymph nodes in question (Wolvers et al., 1999). In contrast, in the remaining 203 studies the exact scientific identification of the node was lacking: 59 of these investigations referred to previous publications in which the nomenclature used was not based on a sufficiently scientific anatomical support, while in the remaining 144 articles no anatomical reference was given at all.

In an attempt to rectify this situation, we first characterized the lymph nodes in BALB/cAnNCrl mice and then summarized our findings in an anatomical chart.