Area of the Fabricius lobules enlarges gradually, the same as cortical thing and medullary thing of the Fabricius lobules.These characteristics were useful for strengthening the immune function.

• 法氏囊淋巴滤泡面积逐渐增大，皮质部和髓质部的面积也增大，淋巴细胞增多，免疫能力加强。