Combination of fixative agents and fixation times to visually differentiate the cortical from the medullary layer in bovine adrenal glands

Abstract Chronic stress exposure commonly increases adrenals weight and changes their morphology. This study aimed to compare four methods to delimitate the cortical and medullary layers of adrenals glands in Nelore bulls. Fresh adrenals did not present differentiation between layers. Then, frozen adrenals were distributed in plastics bags with fixative Bouin (G1), 96ºGL ethylic alcohol (G2), 10% formaldehyde (G3), or 2.5% glutaraldehyde (G4). After 12 hours of fixation, the G1 adrenal glands did not show the entire cortical layer marked by Bouin’s solution. For G2 and G3 there was a poor contrast, while for G4 there was a reasonable contrast. After 24 hours of fixation, G1 had an excellent contrast between layers, while G2 and G4 had a reasonable contrast and G3 a very bad contrast. After 48 hours it was difficult to differentiate cortical and medullar layers for G1; for Group 2 we get a reasonable contrast; and for G3 the contrast was bad. For G4 the contrast was not as sharp due to the medulla became dark. It was concluded that fixation of adrenals must be done in Bouin’s solution for 24 hours to obtain an effective evaluation of the adrenals’ morphometry.

摘要：慢性应激暴露通常会增加肾上腺重量并改变其形态。本研究旨在比较四种用于区分内洛尔公牛(Nelore bulls)肾上腺皮质与髓质层的方法。新鲜肾上腺组织无法区分皮质与髓质两层结构。随后将冷冻肾上腺分装于塑料袋，分别采用博恩固定液(Bouin's solution，G1)、96%乙醇(ethylic alcohol，G2)、10%甲醛(formaldehyde，G3)以及2.5%戊二醛(glutaraldehyde，G4)进行固定。固定12小时后，G1组的肾上腺未能被博恩固定液完整标记出皮质层；G2与G3组对比度较差，G4组则对比度尚可。固定24小时后，G1组皮质与髓质层间对比度极佳，G2与G4组对比度尚可，G3组对比度极差。固定48小时后，G1组难以区分皮质与髓质层；G2组对比度尚可；G3组对比度较差；G4组因髓质变黑，对比度表现不佳。本研究最终得出结论：若要实现肾上腺形态计量学(morphometry)的有效评估，需采用博恩固定液固定肾上腺组织24小时。