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Developmental changes of the proliferative response of mouse epidermal melanocytes to skin wounding
1Division of Biology, National Institute of Radiological Sciences, Chiba, Japan.
Abstract:
A cut was made on the middorsal skin of mice of various ages of strain C57BL/0J using fine iridectomy scissors. Specimens from the wounded skins were fixed at various days after wounding and were subjected to the dopa reaction and to the combined dopa-premelanin reaction. When the dorsal skins of 1.5-day-old mice were wounded, the melanocyte population positive to the dopa reaction as well as the melanoblast-melanocyte population positive to the combined dopa-premelanin reaction increased dramatically in the epidermis adjacent to a skin wound. Pigment-producing melanocytes in mitosis were frequently found in the vicinity of a wound immediately after wounding. When the dorsal skins of 4.5-day-old mice were wounded, the increase in the melanocyte and melanoblast-melanocyte populations was smaller than that of 1.5-day-old mice. The increase in number of pigment-producing melanocytes in mitosis was reduced and delayed as compared to 1.5-day-old mice. When the dorsal skins of 8.5-, 20.5-, and 60.5-day-old mice were wounded, the increase in the melanocyte and melanoblast-melanocyte populations was much smaller than the newborn mice. Moreover, pigment-producing melanocytes in mitosis were never found. These results indicate that the proliferative response of mouse epidermal melanocytes to skin wounding becomes delayed and diminished with development.
Insights
The skin wound response in mice shows that young mice have a greater increase in melanocytes and melanoblasts after injury. This proliferative response diminishes significantly with age.
Area of Science:
- Developmental Biology
- Dermatology
- Cell Biology
Background:
- Melanocytes are crucial pigment-producing cells in the epidermis.
- Understanding the regenerative capacity of melanocytes after injury is important for wound healing research.
Purpose of the Study:
- To investigate the age-dependent proliferative response of mouse epidermal melanocytes to skin wounding.
- To characterize the changes in melanocyte and melanoblast populations following injury in mice of different developmental stages.
Main Methods:
- Skin wounding was induced on the middorsal skin of C57BL/0J mice of various ages.
- Tissue specimens were collected at different time points post-wounding.
- Dopa reaction and combined dopa-premelanin reaction were used to identify and quantify melanocytes and melanoblasts.
Main Results:
- In 1.5-day-old mice, skin wounding led to a dramatic increase in epidermal melanocyte and melanoblast populations adjacent to the wound, with frequent mitotic activity observed.
- In 4.5-day-old mice, the increase in melanocyte/melanoblast populations and mitotic activity was smaller and delayed compared to younger mice.
- In older mice (8.5 days and above), the proliferative response was minimal, and no mitotic pigment-producing melanocytes were observed.
Conclusions:
- The proliferative response of mouse epidermal melanocytes to skin wounding is highly dependent on age.
- This response is significantly diminished and delayed in older mice, indicating a developmental decline in regenerative capacity.
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