In order to study on the morphological changes of mast cells in the rat mesentery under acute dehydration and convalescence, this experiment was performed. The female adult Swiss albino rat weighing about 200 gm were divided into normal, dehydration and convalescence group. The dehydrated rats obtained by absolute restriction of drinking water were sacrificed on the 1st, 2nd, 3rd, 4th and 5th day, and convalescent rats obtained by permission of drinking water ad libitum after the 5 days-restriction were sacrificed on 1st, 2nd, 3rd, 5th and 10th day. All of experimental
rats were kept under constant room temperature and humidity. Mesenteries were taken from the animals under ether anesthesia and fixed in 10% buffered formalin and made in to preparation stained with 0.1% toluidin blue.
The average number of total mesenteric mast cells and degranulated mast cells were counted in each specimen over 10 view-fields by magnification of 160×, and morphological changes of the cells were also observed in each group.
The results of this study were summarized as follows:
1. The average number of the mesenteric mast cells of normal rat was 312.9. Most of the cells were of a rich granular type showed a strong metahrcomatic reaction, and those of a degranulated type were very few.
2. In the dehydration group, this study showed no significant alteration in the number of mast cells following acute dehydration, but numbers of the degranulated mast cells significantly increased on late stage (4-day and 5-day group) of the dehydration. The mast cells were more irregular shaped, the granules of the cells showed weak stainability to a orthochromasia, and more vacuolation in the cytoplasm were seen. Atypical or degenerative mast cells which were abnormally large-sized, contained weakly stained conglomerated cytoplasmic granules and cytoplasmic vacuoles of various
sizes.
3. In the convalescence group, the total number of mesenteric mast cells showed no significant changes, but relatively increased degranulated cells and their morphological
changes were remained on the 1st to 3rd convalescent day group, but recovery of the shape and structure of mast cells was notably seen thereafter.
4. According to the above findings, the morphological changes of mesenteric mast cells under dehydrated condition provably occurred as a favorable biological phenomena.
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