Nile tilapia (Oreochromis niloticus) skin is a well-known biomaterial used as an occlusive dressing for burn treatment. It is also an inexpensive and important source of collagen. This study aims to describe the ultrastructural aspects of Nile tilapia skin, assess its collagen amount and organization, and compare quantitative methods of histochemical and immunohistochemical analysis (in all sterilization steps for use in burn dressings). One sample (0.5 $\times$ 0.5 cm) of ten different fish skins was divided in four groups: in natura skin (IN), chemical sterilization (CH), additional irradiation (30 kGy) (IR), and skins used in burn treatment (BT) to compare histochemical and immunohistochemical findings of collagen amount and describe ultrastructural aspects through scanning electron microscopy. The amount of type I collagen decreased during sterilization and clinical use owing to gradual reduction of immunostaining (anti-collagen-I) and decreasing fiber thickness of the collagen, when compared to type III (Picrosirius-red-polarized light). The collagen fibers were rearranged at each sterilization step, with a low collagen percentage and large structural disorganization in BT. The amount of type-I collagen was further reduced after BT (p < 0.05). Both the methods did not exhibit a quantified value difference (p = 0.247), and a positive correlation (r = 0.927; 95 % CI = 0.720–0.983) was observed between them, with concordance for collagen quantification in similar samples, presenting a low systematic error rate (Dalberg coefficient: 6.70). A significant amount of type-I collagen is still observed despite sterilization, although clinical application further reduces type I collagen. Its quantification can be performed both by immunohistochemistry and/or Picrosirius Red reliably.

尼罗罗非鱼（Oreochromis niloticus）皮肤是一种众所周知的生物材料，用作烧伤治疗的封闭敷料。它也是一种廉价且重要的胶原蛋白来源。本研究旨在描述尼罗罗非鱼皮肤的超微结构方面，评估其胶原蛋白含量和组织，并比较组织化学和免疫组织化学分析的定量方法（用于烧伤敷料的所有灭菌步骤）。一个样品（0.5$\times$0.5 cm) 将十种不同的鱼皮分成四组：在 natura皮肤 (IN)、化学消毒 (CH)、额外照射 (30 kGy) (IR) 和用于烧伤治疗 (BT) 的皮肤，以比较胶原蛋白量的组织化学和免疫组织化学结果，并通过扫描电子显微镜描述超微结构方面。与 III 型（Picrosirius-红偏振光）相比，由于免疫染色（抗胶原蛋白-I）逐渐减少和胶原纤维厚度减少，I 型胶原蛋白的量在灭菌和临床使用期间减少。胶原纤维在每个灭菌步骤中重新排列，在 BT 中胶原百分比低且结构混乱。BT 后 I 型胶原蛋白的量进一步减少 (p < 0.05)。两种方法均未表现出量化值差异 (p = 0.247) 和正相关 (r = 0.927; 95 % CI = 0.