Numbers of granulocytes in thymic imprints of rabbits of different ages and degrees of coccidial parasitism.

Abstract

Counts of granulocytes were performed on thymic imprints from normal rabbits 3 days old, 2–3 weeks old, and young adults, and from young adult rabbits mildly and severely parasitized with coccidiosis. Analyses of percentages of eosinophils, heterophils, and basophils indicated no sex differences. Comparisons of relative numbers of granulocytes in normal rabbits showed that young adult rabbits possessed more eosinophils and fewer basophils than the younger groups (no differences in heterophils); 3-day-old rabbits had more eosinophils than the 2-to 3-week animals (no differences in heterophils and basophils). No differences in relative numbers of the various granulocytes were found in the mildly and severely parasitized rabbits, but there was a decrease in eosinophils in the parasitized rabbits when compared with the young normal adult rabbits. Eosinophilic leukocytes were divided into two groups: the mononuclear "tissue" line and the lobated "blood" line of development. In the 3-day-old rabbits about 95% of eosinophils were of the lobed variety but in the older normal rabbits, the two developmental lines were about equal in numbers. When compared with the normal young adult rabbits, parasitized rabbits have increased percentages of "blood" eosinophils as a result of greater numbers of band and polymorphonuclear cells.