Changes in the thymus and spleen of the turtle Mauremys caspica after testosterone injection: a morphometric study.
To confirm a possible role of sex hormones in governing the seasonal variations affecting the reptilian lymphoid organs, a morphometric analysis was carried out on the thymus and spleen of turtles, Mauremys caspica, intraperitoneally injected with a single dose of testosterone propionate (TP) at the third week of June when physiological levels of testosterone are low. At 4 and 6 weeks, control turtles show an apparent lymphocyte mobilization both from thymus and spleen with a decrease in the percentage of thymic cortex, numbers of cortical lymphocytes, and mitotic index, but increased numbers of medullary lymphocytes. In the thymic cortex of treated turtles, there is a decrease in the same parameters but they occur in the first 2 weeks, whereas the medullary lymphocytes also undergo reduction at 4 and 6 weeks. In addition, the number of reticuloepithelial cells per area unit decreases at 2 weeks in the thymic cortex of treated turtles. These results are discussed from the point of view of a biphasic effect of testosterone on turtle lymphoid organs: In the first weeks, the changes observed could be attributed to the high levels of testosterone; after 4 and 6 weeks, variations are dependent both on long-term effects of testosterone and on those induced by the high values of corticosterone occurring in summer.
Varas
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A
Department of Cell Biology, Faculty of Biology, Complutense University, Madrid, Spain.
Torroba
M
M
Zapata
A G
AG
D000818:Animals; D016923:Cell Death; D008297:Male; D008940:Mitotic Index; D012621:Seasons; D013154:Spleen / Q000166:cytology / Q000187:drug effects*; D013601:T-Lymphocytes / Q000166:cytology / Q000187:drug effects; D013739:Testosterone / Q000494:pharmacology / Q000502:physiology*; D013950:Thymus Gland / Q000166:cytology / Q000187:drug effects*; D014426:Turtles / Q000276:immunology / Q000502:physiology*
D013739:Testosterone