瑞氏海豚低色素沉澱疤痕之組織病理學研究

Abstract

瑞氏海豚（Grampus griseus），或稱花紋海豚，因其皮膚上明顯的大量疤痕而聞名，這些疤痕通常是由海豚之間的牙齒刮傷或達摩鯊（Isistius brasiliensis）咬傷所造成。這些疤痕通常呈灰色至白色，使其在瑞氏海豚身上更加顯眼。瑞氏海豚的低色素沉澱疤痕具有獨特而高度重複的特徵。癒合的白色疤痕，即先前由達摩鯊咬傷所造成的深度傷口，從中心至最外層分為四部分：（1）中央白色區域，（2）遷移線，（3）周圍區域，（4）未受傷的皮膚。此為第一個針對瑞氏海豚皮膚組織學和低色素沉澱疤痕病理學方面的研究，結果顯示於瑞氏海豚的正常皮膚中，深色皮膚相較淺色皮膚擁有更多的黑色素細胞，且白色皮膚仍含有少量的黑色素細胞；於黑色素顆粒染色中亦發現深色皮膚相較淺色皮膚可見更多黑色素顆粒，且白色皮膚仍可見少量黑色素顆粒。於瑞氏海豚的低色素沉澱疤痕中未發現黑色素細胞及黑色素顆粒。此結果與先前於人類和杜洛克豬的低色素沉澱疤痕所發現的特徵不同，人類及豬的疤痕中仍可見黑色素細胞，但未見黑色素顆粒。研究結果還發現，瑞氏海豚的愈合傷口周圍存在黑色素細胞脫離的現象。此外，在網狀真皮中發現強烈的黑色素細胞抑制因子，如Dickkopf-1。這些證據皆表明瑞氏海豚的低色素沉澱疤痕形成機制與陸地動物不同，且類似於人類白癜風患者患處的組織病理特徵。

Risso's dolphin (Grampus griseus) is renowned for its prominent scarring, often resulting from tooth-rake marks during dolphin interactions or bites from cookiecutter sharks (Isistius brasiliensis). These scars are typically gray to white, making them conspicuous on the skin of Risso's dolphins. The hypopigmented scars in Risso's dolphins exhibit distinctive and highly repetitive characteristics. The healed white scars, which represent previously deep wounds caused by cookiecutter shark bites, can be divided into four parts from the center to the outermost layer: (1) the central white area, (2) migrating lines, (3) periphery area, and (4) the unwounded skin. This study represents the first investigation into the histology of Risso's dolphin skin and the pathology of hypopigmented scars, revealing that the darker skin regions contain a higher number of melanocytes compared to the lighter regions, while even the white skin still contains a small number of melanocytes. Additionally, darker skin areas exhibit more melanin granules than lighter skin areas, and some melanin granules are also present in the white skin areas. In the hypopigmented scars of Risso's dolphins, no melanocytes or melanin granules were observed. These findings differ from the characteristics of hypopigmented scars in human and duroc pig, where melanocytes are still present but melanin granules are absent. The study also observed melanocytes detachment in the healing wounds of Risso's dolphins. Furthermore, strong melanocyte-inhibiting factors, such as Dickkopf-1, were found in the reticular dermis. Taken together, this evidence suggests that the mechanism of hypopigmented scars in Risso's dolphins differs from that in terrestrial animals and shares similarities with the pathological features observed in human vitiligo patients.