Size of Thymus and Bursa Fabricius in Relation to Rate of Growth in Chicks

IT HAS frequently been noted that the thymus of rapidly growing chickens is large, whereas that of slowly growing chickens is relatively very small. Ackert (1924) found that the thymus glands of chickens parasitized with Ascaridia perspicillum were smaller than those of non-parasitized chickens. However, Riddle and Krizenecky (1931) reported that the removal of both the thymus and the bursa Fabricius from 17 common pigeons did not affect development or function of the reproductive organs. They suggested that other organs, particularly lymph nodes, might have thymic functions. Plagge (1941) has concluded that the thymus glands of male and female albino rats are definitely sensitive to varying concentrations of sex hormones as indicated by gross changes in the thymus at puberty and by both gross and histological changes following castration or injections of sex hormones. Thymectomy does not affect the reproduction system of either sex. As the physiological relationship between the . . .