Healing of cutaneous wounds in a freshwater teleost, Labeo rohita: Scanning electron microscopical investigation

Abstract

In this study, healing of cutaneous wounds in Labeo rohita using scanning electron microscope is reported. Wound area could be divided into three regions. Immediately after infliction of wound, edges retract exposing underlying tissues in wound gap (Region I). Simultaneously, at region close to wound edge (Region II), mucous goblet cell openings are observed with copious mucous secretions. Within 1 h, Region I gets covered by mucous secretions, and epidermis at edges starts migrating. Opposing fronts gradually advance and by 4-6 h come in contact to epithelialize wound gap. Zone of contact of fronts is demarcated by epidermal ridge, which is relatively prominent at 8 h. It gradually diminishes and is not distinguished at 24 h and afterward. At 1-4 h, microridges on epithelial cell surfaces appear irregularly arranged, widely spaced, short with abrupt ends at Region I; relatively extensive at Region II; and similar to those in controls at region surrounding Region II (Region III). At 12 h and afterward, microridges appear similar to those in controls at Regions I and II. At 1-2 h, isolated swollen epithelial cells, often in process of detachment and exfoliation at surface, are observed at Regions I and II. Such cells are infrequent at 8 h and afterward. Region I covered by migrated epidermis appears trough like at 4 h to 2 days, level of which gradually rises and at Day 4, surface of epidermis appears at a level similar to that at Regions II and III. Changes have been associated with the imbalance of osmotic homeostasis due to disruption of barrier between internal and external environment of skin.

Actin Microridges

“…More recent studies of microridge dynamics (Sharma et al, ) raise the possibility that the microridges could act as a stable reserve of pre‐polymerized F‐actin that is rapidly utilized during cellular remodeling, such as would occur during the wound healing process. This is consistent with the in vivo wound‐healing studies noted earlier (Rai et al, ; Richardson et al, ; Verma et al, ) where surface microridges are fragmented and lost in the epidermis closest to the wound site. Disassembly of the microridges could “feed” actin oligomers into the cytoskeleton of actively migrating epidermal cells, thus supporting rapid wound closure.…”

Wound healing in post-smolt Atlantic salmon (Salmo salar L.)

“…Analysis of the flat keratocytes at the wound surface also showed a different cell morphology of the cells located at the wound margins and those at the wound center. A similar appearance of flat keratocytes at the margins and elevated epithelial cells at the wound center has been reported in healing wounds of the teleost fish rohu carp ( Labeo rohita ) 61 . Thus, it appears that the epidermal layer at the edges of the wounds has a different function to the cells located at the wound center.…”

Dorso-ventral skin characterization of the farmed fish gilthead seabream (Sparus aurata)

“…Interestingly, the cell area (Fig 5A) and the area occupied by microridges (Fig 5B) are larger in the dorsal region than in the ventral region. There is no previous information about the differences in cell size or in the area of microridges for the apical part of the cells, except one work that describes preliminary data on microridges in wound healing [30]. It would be interesting to investigate alterations in the same since they seem to be involved not only in mechanical protection but also in the capacity to hold the skin mucus [4], and therefore in a better mucosal immune barrier.…”