The midgut gland cell differentiation occurs at Z2, There are 4 types of cells, i. e., embryonic cell (E-cell), fibrillar cell (F-cell), blister cell (B-cell) and resorptive cell(R-cell).

中管上皮在Z2期已有了化，由4类组成，即胚(E)、纤维(F)、泡状(B)和吸收(R)。