Wound repair in the marine worm Sipunculus nudus (Sipunculidae)

Abstract

The cells and molecules involved in the wound healing of Sipunculus nudus were studied. An incision,
5 mm in length, was cut longitudinally at a site opposite the anus and 10 mm from the introvert. The
histological study performed at different times showed an involvement of both Type I and Type II
granulocytes in the process of healing. The former were capable of extracellular digestion and they
were immunoreactive to anti-IL-4, -IL-10 and -epidermal growth factor (EGF) antibodies (Abs); the latter were involved in the synthesis of connective tissue from 24 h after the incision, thereby causing
the initial closing of the wound. After 70 h, a continuous layer of Type II granulocytes was found on the sides of the wound where the future muscle tissue would be formed; many of these granulocytes had been partially degranulated. It was not possible to establish any existing relationship between the functions of Type I granulocytes and their reactivity to anti-IL-4, -IL-10 and -EGF Abs.