(a)
(b)
(c)
(d)
Figure 1: Photography of Bombyx mori silk gland (a), stained with light green 1%. Anterior (ASG), middle (MSG), and posterior silk gland (PSG). MSG and its areas: anterior (1), anterior-middle (2a), posterior-middle (2b), and posterior (3). Head (H). In (b), (c), and (d), photomicrographs of different regions anterior, middle, and posterior, respectively, stained with haematoxylin and eosin. Cytoplasm (Cy), nucleus (arrows), and lumen (Lu).