微丝蚴是丝虫类寄生虫的幼虫阶段，在医学上具有重要意义，是诊断丝虫病的关键依据。它们本身不直接繁殖，但可被中间宿主(媒介昆虫)吸血时吸入，并在昆虫体内发育成为具有感染性的幼虫，从而完成传播循环。微丝蚴通常出现在终宿主的血液或皮肤中。
微丝蚴在宿主外周血液中的出现呈现出昼少夜多的周期性变化。白天，它们主要集中在肺部等深层组织的毛细血管中；夜晚(通常在晚上10点至次日凌晨2点），则大量出现在外周血液中。这恰好与媒介蚊虫的吸血时间(夜晚)同步，极大地增加了传播效率。因此，临床采血检查微丝蚴必须在夜间进行，否则检出率极低。
不同种类的丝虫其微丝蚴的形态、在人体内的分布及所致疾病也不同。常见的人类丝虫：班氏丝虫、旋盘尾丝虫、马来丝虫等。鉴别不同种类微丝蚴的主要形态学依据包括：
体核：虫体内有大量细胞核，称为体核。观察体核的形态、大小和分布是鉴别的关键。
头间隙：虫体最前端无体核的区域。测量头间隙的长度与宽度比例具有重要意义。
尾核：有些虫种(如班氏微丝蚴)尾部没有体核，而有些(如马来微丝蚴)尾部有2个尾核。
微丝蚴可采用鲜血直接涂片镜检，但检出率较低，不能确定虫种，多与用于宣传教育。如采用血膜涂片染色镜检不仅微丝蚴的内部结构清晰可见，而且对于虫种的鉴定、保存都有利。
微丝蚴虫体外常包裹着一层鞘膜，在染色片中，鞘膜通常不着色，因此虫体看起来像位于一个透明的套子内。常用的形态学观察方法有瑞氏或吉姆萨染色法、代氏苏木素染色法和硼砂美蓝染色法。在显微镜下，经吉姆萨染色后的微丝蚴呈现为细丝状、无色透明的虫体，头端钝圆，尾端尖细。经硼砂美蓝染色后，虫体色泽鲜艳，鞘膜清楚，头间隙、体核、尾核、神经环清断；鞘膜呈淡红色，体核呈蓝色。
该试剂仅用于科研领域，不适用于临床诊断或其他用途。
自备材料：
1、 载玻片、普通光学显微镜、盖玻片
2、 蜡笔、甲醇、蒸馏水
操作步骤(仅供参考)：
1、 采血时间：以夜间9时至次晨2时为宜；采血部位：耳垂、指尖、婴儿的足底等。
2、 制作血膜：厚血膜比吉姆萨染色的厚血膜略薄，可用3μl血涂成直径为1.2~1.5cm的亚厚血膜；薄血膜则不宜过薄，可在涂片时推片以45°角涂成较厚的薄血膜。
3、 固定：待血膜充分晾干后，用玻璃棒蘸取甲醇或无水酒精轻轻抹过薄血膜，以使细胞固定。厚血膜固定前必须先进行溶血，用滴管滴儿滴水于厚血膜上，待血膜呈灰白色，将水倒去，晾干后再用甲醇或无水酒精固定。如薄、厚血膜在同一张载玻片上，可用蜡笔在薄血膜染色区两端划线，在厚血膜周边画圈，可避免在溶血和固定过程中互相影响。
4、 配制硼砂美蓝染色工作液：取0.5ml 微丝蚴染色液(硼砂美蓝染色液)，加入9.5ml蒸馏水，混匀，一般建议临用前稀释。
5、 用硼砂美蓝染色工作液染色10分钟。
6、 水洗，晾干，镜检。
染色结果：
微丝蚴鞘膜呈淡红色，体核呈蓝色。
注意事项：
1、 涂制血膜用的载玻片使用前需经铬酸洗液处理。
2、 染色用的血膜厚薄应符合要求。
3、 一般建议临用前稀释，不宜存放过久。
4、 滴加染色液应以完全覆盖血膜为准。
5、 为了您的安全和健康，请穿实验服并戴一次性手套操作。
试剂开封后请尽快使用，以防影响后续实验效果。
Microfilariae are the larval stage of filarial parasites, which are of great medical significance and serve as the key basis for the diagnosis of filariasis. They do not reproduce directly themselves, but can be ingested by intermediate hosts (vector insects) during blood-sucking, and develop into infective larvae within the insects, thereby completing the transmission cycle. Microfilariae usually occur in the blood or skin of definitive hosts.
The presence of microfilariae in the peripheral blood of hosts exhibits a periodic variation characterized by fewer numbers during the day and greater numbers at night. During the daytime, they are mainly concentrated in the capillaries of deep tissues such as the lungs; at night (usually from 10:00 p.m. to 2:00 a.m. the next day), they appear in large quantities in the peripheral blood. This is exactly synchronized with the blood-sucking time of vector mosquitoes (at night), which greatly improves the transmission efficiency. Therefore, clinical blood collection for microfilariae examination must be conducted at night; otherwise, the detection rate will be extremely low.
Different species of filarial worms vary in the morphology of their microfilariae, their distribution in the human body, and the diseases they cause. Common human-infecting filarial worms include Wuchereria bancrofti, Onchocerca volvulus, and Brugia malayi, etc. The main morphological criteria for identifying different species of microfilariae are as follows:
Somatic nuclei: The worm body contains a large number of nuclei, known as somatic nuclei. Observing the morphology, size, and distribution of somatic nuclei is the key to identification.
Cephalic space: The nuclear-free region at the anterior-most end of the worm body. Measuring the length-width ratio of the cephalic space is of great significance.
Caudal nuclei: Some species (e.g., Wuchereria bancrofti microfilariae) have no somatic nuclei in the tail region, while others (e.g., Brugia malayi microfilariae) have two caudal nuclei in the tail.
Microfilariae can be examined by direct microscopic observation of fresh blood smears, but this method has a low detection rate and cannot determine the species, so it is mostly used for publicity and education purposes. In contrast, microscopic examination of stained blood smears not only allows clear visualization of the internal structures of microfilariae, but also facilitates species identification and specimen preservation.
Microfilariae are usually enveloped by a sheath. In stained smears, the sheath is generally non-staining, so the worm body appears to be located within a transparent envelope. Commonly used morphological staining methods include Wright's staining, Giemsa's staining, Delafield's hematoxylin staining, and borax methylene blue staining. Under the microscope, microfilariae stained with Giemsa's stain appear as filamentous, colorless and transparent organisms with a rounded anterior end and a tapering posterior end. After staining with borax methylene blue, the worm body shows bright coloration with a clearly defined sheath; the cephalic space, somatic nuclei, caudal nuclei, and nerve ring are distinctly visualized; the sheath stains pale red and the somatic nuclei stain blue.
This reagent is for research use only and is not intended for clinical diagnosis or any other purposes.
Self-prepared Materials:
1. Glass slides, ordinary light microscopes, and coverslips
2. Wax pencils, methanol, and distilled water
Operating Procedures (For Reference Only):
1. Blood collection time: Optimal between 9:00 p.m. and 2:00 a.m. the next day. Blood collection sites: Earlobes, finger pulps, soles of infants’ feet, etc.
2. Preparation of blood films: The thick blood film should be slightly thinner than that used for Giemsa staining; a sub-thick blood film with a diameter of 1.2–1.5 cm can be prepared using 3 μl of blood. The thin blood film should not be overly thin; it can be spread at a 45° angle to make a relatively thick thin blood film.
3. Fixation: After the blood films are completely air-dried, dip a glass rod into methanol or anhydrous alcohol and gently wipe the thin blood film to fix the cells. Before fixing the thick blood film, hemolysis must be performed first: add a few drops of water onto the thick blood film using a dropper; once the film turns grayish white, pour off the water, air-dry it, and then fix it with methanol or anhydrous alcohol. If both thin and thick blood films are prepared on the same glass slide, draw lines at both ends of the stained area of the thin film and a circle around the thick film with a wax pencil to prevent mutual interference during hemolysis and fixation.
4. Preparation of borax methylene blue working staining solution: Take 0.5 ml of microfilaria staining solution (borax methylene blue staining solution), add 9.5 ml of distilled water, and mix well. It is generally recommended to dilute the solution immediately before use.
5. Stain the blood films with the borax methylene blue working solution for 10 minutes.
6. Rinse with water, air-dry, and observe under the microscope.
Staining Results:
The sheath of microfilariae appears pale red, while the somatic nuclei stain blue.
Precautions:
1. Glass slides for preparing blood films shall be treated with chromic acid cleaning solution prior to use.
2. The thickness of blood films for staining must meet the required specifications.
3. It is generally recommended to dilute the solution immediately before use; prolonged storage is not advisable.
4. The staining solution should be added in an amount sufficient to completely cover the blood films.
5. For your safety and health, please wear a lab coat and disposable gloves during the operation.
6. Please use the reagent as soon as possible after opening to avoid affecting subsequent experimental results.
ZJ26F0232076
危险品化学品经营许可证（带存储）