Scanning electron microscopy of epidermal cell migration in wound healing during limb regeneration in the adult newt, Notophthalmus viridescens

Abstract

The epidermal cells which migrate over the wound surface of the amputated limb of the adult newt were examined using the scanning electron microscope. Specimens were prepared routinely for scanning electron microscopy or were embedded in Epon 812 for light microscopic observations. A cuff of epidermal cells was seen at the edge of the wound, from which cells appeared to migrate over the wound surface. As early as five hours after transection of the limb, the basal layers of this cuff appeared to send out pseudopodial projections. These seemed to establish a physical contact with a fibrin-like substratum, which apparently served as a means of support for the migrating cells. Subsequently, the epidermal cells became elongate and had the appearance of streaming toward the center of the wound. Between 10 and 13 hours post-amputation, the cells in the central region of the stump were rounded up and some possessed microappendages resembling microplicae and microvilli. Throughout the entire period of wound coverage, the cells seemed to maintain contact with the fibrin network, which appeared to be the first structural element of wound architecture. As a result of these observations, the mechanism by which the epidermal cells migrate has been clarified.

Limb regeneration in higher vertebrates: Developing a roadmap

“…This process is initiated by cells at the wound edge extending lamellipodia and actively moving across the wound, and more proximal cells similarly extending lamellipodia behind these lead cells (Mahan and Donaldson, 1986;Dungan et al, 2002). Urodele wound closure occurs incredibly fast; in young axolotls, an amputation wound is closed within 4 hr (Carlson et al, 1998), and in the adult newt, wound closure is completed in less than 12 hr (Repesh and Oberpriller, 1978). By comparison to a similar-size mammalian wound, for example, an amputated mouse digit that takes multiple days to close, the speed of urodele wound closure is extraordinary.…”

Mechanisms of urodele limb regeneration

“…The epidermal basal cells at the edge of the cut skin lose their intercellular junctions and hemidesmosomal junctions that adhere them to the basement membrane and migrate through the clot to close the wound within a few hours. The migrating cells do not divide (Hay & Fischman, 1961), but a zone of dividing epidermal cells proximal to the wound edge supplies a continual stream of migrating cells (Lash, 1955; Repesh & Oberpriller, 1978, 1980). Fibronectin in the clot is the adhesive substrate for the migrating epithelial cells (Donaldson & Mason, 1977; Donaldson, Mahan, Yang, & Crossin, 1991; Repesh, Furcht & Smith, 1981).…”

Looking Ahead to Engineering Epimorphic Regeneration of a Human Digit or Limb

“…36 A wound epithelium (WE) forms within 12 h from cells that have migrated from the surrounding tissue of the amputation plane. 37 This WE isolates and protects the wound from further external insults (reviewed in Han et al…”