The microsporidia Nosema apis and Nosema ceranae are major honey bee pathogens that possess different characteristics in terms of the signs they produce, as well as disease development and transmission. Although the ventricular epithelium is generally considered the target tissue, indirect observations led to speculation that N. ceranae may also target other structures, possibly explaining at least some of the differences between these 2 species. To investigate the tropism of Nosema for honey bee tissues, we performed controlled laboratory infections by orally administering doses of 50 000 or 100 000 fresh mature spores of either species. The fat body was isolated from the infected bees, as well as organs from the digestive (esophagus, ventriculus, ileum, rectum), excretory (Malpighian tubules), circulatory (aorta, heart), respiratory (thoracic tracheas), exocrine (hypopharyngeal, mandibular and labial, cephalic, thoracic salivary glands), and sensory/nervous (brain, eyes and associated nerve structures, thoracic nerve ganglia) systems. Tissues were examined by light and electron microscopy at 7, 10, and 15 days postinfection. Both Nosema species were found to infect epithelial cells and clusters of regenerative cells in the ventriculus, and while the ileum and rectum contained spores of the microsporidia in the lumen, these structures did not show overt lesions. No stages of the parasites or cellular lesions were detected in the other organs tested, confirming the high tropism of both species for the ventricular epithelium cells. Thus, these direct histopathological observations indicate that neither of these 2 Nosema species exhibit tropism for honey bee organs other than the ventriculus.

中文翻译：

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工蜂（Apis mellifera）中的Nosema apis和Nosema ceranae组织趋向。

小孢子虫Nosema apis和Nosema ceranae是主要的蜜蜂病原体，就其产生的体征以及疾病的发展和传播而言，具有不同的特征。尽管通常将心室上皮视为靶组织，但间接观察导致推测，猪笼草也可能靶向其他结构，这可能解释了这两种物种之间的至少某些差异。为了研究Nosema对蜜蜂组织的嗜性，我们通过口服施用任何种类的5万或10万新鲜成熟孢子进行了受控实验室感染。从感染的蜜蜂以及消化器官（食道，心室，回肠，直肠），排泄物（马尔皮安小管），循环系统（主动脉，心脏）的器官中分离出脂肪体，呼吸（胸气管），外分泌（下咽，下颌和唇，头，胸唾液腺）和感觉/神经（大脑，眼睛和相关的神经结构，胸神经节）系统。感染后第7、10和15天通过光镜和电子显微镜检查组织。发现这两种Nosema物种都感染上皮细胞和脑室中的再生细胞簇，而回肠和直肠的管腔中含有微孢子虫的孢子，但这些结构未显示明显的病变。在测试的其他器官中未检测到任何阶段的寄生虫或细胞病变，证实了这两种物种对心室上皮细胞的高嗜性。从而，