Observations on a new liver inclusion in the mouse

A hitherto unrecognised lipoprotein liver-cell inclusion is described in elderly mice. The significance of these inclusions is unknown. In an experiment to determine the effect of Trepo-nema pallidum on the lifespan of mice (Wright & Wharton, ] 977) an inclusion which had not prev-iously been described was detected in the liver. 30 were inoculated intra peritoneally with a formalin-killed suspension, JO with only the suspending medium, and 20 uninoculated mice were held over for the period of the experiment. From the infected group JO mice were sacrificed at intervals of 6 months, while 10 mice inoculated with dead spirochaetes were killed at 30, 36 and 42 months following the commencement of the experiment. Organs of all these mice were submitted to microscopical ex-amination. Table 1. Tests performed on the liver inclusions. Presence or Conclusion absence Materials and methods Animals All mice used in this study were inbred CBA mice fed on an antibiotic-free diet and water ad libitum. 70 mice of 6 weeks of age were infected with the suspension adjusted to contain 107 live T. pa/lidum (Nichols strain) by the intraperitoneal route (Wright & Wharton, 1977). Rhodamine (on imprints