Evaluation of different fixatives for histological studies in canine ear skin

ABSTRACT The biological fixatives have an important role in the final histology quality. In veterinary, routine skin biopsy is a common procedure and the choice of fixative is essential for the final result. The most common fixative is Formalin, even though it is toxic, carcinogenic, and has low and slow penetration. Still, there isn't a fixer which can replace the qualities of formalin. The aim of this study was to evaluate qualitatively the preservation of the histological features of dog skin using different tissue fixative embedded in paraffin, sectioned and stained with hematoxylin - eosin. We used a 4 mm punch pen to collect ear skin samples in six dog cadavers. After collection, the tissues were fixed in: (1) Bouin for 6 hours; (2) Carnoy for 4 hours; (3) 10% buffered formaldehyde for 24 hours, all under refrigeration (4 ° C). The tissues were then processed, sectioned and stained with hematoxylin and eosin. The slides were evaluated blindly by four different pathologists who considered the qualitative aspects below: (1) quality of coloring; (2) preservation of the histological characteristics; (3) preservation of cytoplasmic boundaries using a Likert scale score for each blade. The fixative with the highest mean score on all items was buffered formalin with 3.76 points followed by Bouin (3.39) and Carnoy (2.52). Formaldehyde can bring health a risk of professional routine handling, so it is necessary to search for a biological fixative with the same qualities being less harmful to health.

摘要：生物固定剂对最终组织学检测质量具有关键作用。在兽医学领域，常规皮肤活检是一项常见诊疗操作，固定剂的选择对最终检测结果至关重要。当前临床最常用的固定剂为福尔马林（Formalin），尽管其具备毒性、致癌性，且渗透能力低且缓慢，但目前尚无任何一种固定剂能够替代福尔马林的各项优良特性。本研究旨在定性评估不同组织固定剂对犬皮肤组织学特征的保存效果，具体方法为将组织进行石蜡包埋、切片后采用苏木精-伊红（hematoxylin-eosin）染色。本研究使用4mm穿孔活检笔采集6只犬尸体的耳皮肤样本，样本采集完成后，将组织分别置于以下冷藏（4℃）条件下固定：(1) 波恩固定液（Bouin）固定6小时；(2) 卡诺伊固定液（Carnoy）固定4小时；(3) 10%缓冲甲醛固定24小时。随后对组织进行常规病理处理、切片并以苏木精-伊红染色。由4名独立病理学家采用盲法对每张切片进行评分，评分维度涵盖：(1) 染色质量；(2) 组织学特征保存情况；(3) 细胞质边界保存情况，所有维度均采用李克特量表进行打分。结果显示，在所有评分项目中平均得分最高的固定剂为缓冲福尔马林（3.76分），其次为波恩固定液（3.39分）与卡诺伊固定液（2.52分）。鉴于福尔马林在常规职业操作中会对从业人员健康构成风险，因此亟需研发一种具备福尔马林同等优良特性且对健康危害更低的生物固定剂。