HISTOLOGICAL AND QUANTITATIVE STUDIES ON THE POSTNATAL GROWTH OF THE THYMUS AND THE BURSA OF FABRICIUS OF WHITE PEKIN DUCKS

概要

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Postnatal growth of the thymus and the bursa of Fabricius of White Pekin ducks was studied with respect to their morphology and gravimetric changes from the day of hatching to 22 weeks of age when they showed sexual maturity. The thymic mean weight reached its maximum at 11 weeks of age, and there-after, a rapid regression mainly due to the depletion of cortex lymphocytes and cyst-formation by epithelial reticular cells in the medulla was observed. Histologically, myoid cells, large and small types of cystic structures formed by epithelial reticular cells, and Hassall's corpuscles could be distinguished in the medulla. The bursa of Fabricius grew actively during the first few weeks of posthatching life and reached its maximum mean weight at 9 weeks of age. Thereafter, the bursa, as well as the thymus, showed a severe regression, and at 22 weeks of age many of the bursae lost their lymphoid follicles and remained as a fibrous sack. Gravimetric changes of the bursa in posthatching life coincided with the growth of bursal lymphoid follicles. The relative number of plasma cells in the interfollicular spaces of the bursa reached their maximum at 3 weeks of age. From morphological results, it was ascertained that the duck's lymphoid system functions actively after the 3-5 weeks of posthatching life, and thus, ducks are available for immunobiological experiments from these weeks.
北海道大学の論文