Cell debris clearance in the integument of the Eri silkworm, Samia ricini

Abstract

The integument of the Eri silkworm, Samia ricini (Lepidoptera, Saturniidae) was observed using fluorescence microscopy by staining with the fluorescent dye DAPI. Intact integument usually consists of a single cell layer of epidermal cells and non-cellular cuticle layers. Partial folding of the epidermis is sometimes observed with cell debris-like structures between the cuticular layers. In order to determine how such structures arise, a part of the integument around the scoli was injured artificially by pinching with forceps so that the epidermal cell layer was disrupted without breaking the cuticle layer. After the injury, some parts of the disrupted epidermal cells had embedded in newly secreted cuticle. These observations suggest that epidermal cell debris is cleared from the wound site by embedding in the cuticle.