Epidermal Mitosis Associated with Knob Formation in the fifth instar larva of the Knobbed Mutant of the Silkworm, Bombyx mori

摘要

During the development of Bombyx mori, cell mitosis normally occurs in epidermal tissues of early larval in-stars, but not during the feeding stage of the final instar. However, in the author's previous paper, it was shown that cell mitosis was stilloccurring in Knobbed mutant (K) larvae at the beginning of the molting period of the fourth instar. This result suggested that epidermal mitosis might persist through the feeding stage of the fifth larval instar. Here, cell mitosis was investigated in the epidermis of Knobbed final instar larvae. The epidermal mitosis was compared between the knobbed and the surrounding unknobbed regions of the fifth larval instar at 48 hours after ecdysis. Mitotic cells were observed in the knobbed region of the secondabdominal segment but not in the non-knobbed surrounding and posterior regions of the same segment. In addition, the corresponding regions of the third abdominal segment did not show mitotic cells.