Résumé
By measuring the absolute weight and growth index of the bursa of Fabricius and using routine H.E method,the growth and histological development of the bursa in 1 to 49 days duckling were studied.The results showed that the absolute weight of the bursa increased as the ducklings grew.The growth index of the bursa reached its peak at 21 days.The height and width of both the large plica and projection formed by the follicle-associated epithelium(FAE)enlarged gradually,the same as the lymphoid follicle area and cortex width.The results indicated that the bursa of Fabricius in duckling develops slowly from 1 to 14 days,and quickly from 14 to 35 days(especially from 21 to 28 days),then steadily from 35 to 49 days.Histologically,the duckling bursa has approached its maturation by the 28th day.