Abstract
The response of germfree mice to subcutaneous (SC) and intraperitoneal (IP) injection of aqueous suspensions of lunar fine material (LFM) was evaluated. Both uninjected mice and mice injected with dry heat sterilized LFM were included as controls. After injection, the majority of mice were subjected to serial sacrifice to assess the time course of the tissue response. A smaller group of animals were held for lifespan studies.
Following IP injection lunar material was rapidly dispersed throughout the peritoneum. Aggregates of LFM could be identified adhering to the serosa of the viscera, omentum and peritoneum. The initial inflammatory response to IP injected material was mixed with both neutrophil and mononuclear leukocytes participating (Figure 4). Five to seven days after injection, the IP lesions consisted of almost pure populations of histiocytes and scattered lymphocytes IFigure 5). Lunar particulates injected IP were disseminated widely via lymphatics and intracellular macrophage transport. Evidence of this transport was provided by the appearance of LFM in the mediastinal lymph nodes of mice within 4 hr of IP injection (Figure 6).
A classic acute inflammatory response to SC injected material was observed. Initially, the response was characterized by edema, vascular congestion, and neutrophil leukocyte infiltration (Figure 7). The edema quickly resolved and by Day 5 post injection, the response was characterized by an almost pure population of mononuclear cells. Rare foreign body giant cells were observed as a component of the SC response after Day 9 (Figure 8).
LFM was observed to persist for the life of the animal (over 20 months). A low grade inflammatory reaction and the absence of significant fibroplasia characterized the end stage lesion. These observations suggest that LFM is relatively insoluble in tissue and that, while acting as a low grade irritant, it has little tendency to evoke reactive fibrosis. The significance of such a chronic low level stimulus and the various factors governing the retention, elimination, and turnover of LFM in mammalian tissue are not clear at this time. Further definitive study will be necessary to determine whether or not the unique chemical and physical properties of LFM will affect such life processes as senescence, disease resistance, or tumorigenesis.
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Lunar Receiving Laboratory: 1970a,Lunar Sample Biomedical Evaluation Procedures for the Maintenance and Support of Laboratory Animals, MSC 03268, November 23.
Lunar Receiving Laboratory: 1970b,Lunar Sample Biomedical Evaluation Sample Preparation and Direct Observation, MSC 03262, April 13.
Lunar Receiving Laboratory: 1971,Lunar Sample Biomedical Evaluation, Microbiology Test Protocol, MSC 03263, January 22.
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Michael Holland, J., Simmonds, R.C. The mammalian response to lunar particulates. Space Life Sciences 4, 97–109 (1973). https://doi.org/10.1007/BF02626346
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DOI: https://doi.org/10.1007/BF02626346