Smith J H, Meier J L, Neill P J, Box E D
Lab Invest. 1987 Jan;56(1):72-84.
Sarcocystis falcatula is a protozoan parasite which obligatorily alternates its definitive host, the opossum (Didelphis virginiana), and a uniquely wide range of avian intermediate hosts. The disease produced by this coccidian parasite in intermediate hosts was studied in the budgerigar bird (Melopsittacus undulatus). Early schizogony occurs in pulmonary endothelial cells, resulting in endothelial cell hypertrophy, capillary obstruction preceding endothelial lysis, acute endophlebitis, and chronic periphlebitis. These impede outflow of the pulmonary vascular system resulting in interstitial, subpneumocytic, and then air-space edema. The edema is associated with retraction and degeneration of squamous pneumocytic processes, loss of the myelinoid "surfactant" covering over the pneumocytes, and atelectasis of the respiratory labyrinth. Epithelial repair is effected by migration of granular pneumocytes (normally confined to the parabronchi and their atria) down the infundibula and into the respiratory labyrinth. This pattern of injury and repair is comparable to diffuse alveolar damage (acute interstitital pneumonitis) of mammals despite the markedly different structure of the avian lung. The implications of this peculiar tissue tropism are discussed.
福氏肉孢子虫是一种原生动物寄生虫，其终末宿主为负鼠（弗吉尼亚负鼠），中间宿主则是种类独特且广泛的鸟类。我们以虎皮鹦鹉（虎皮鹦鹉）为研究对象，探讨了这种球虫寄生虫在中间宿主体内引发的疾病。早期裂殖生殖发生在肺内皮细胞中，导致内皮细胞肥大、内皮溶解前的毛细血管阻塞、急性静脉内膜炎和慢性静脉周炎。这些病变阻碍了肺血管系统的血液流出，进而导致间质、肺泡下以及随后的气腔水肿。水肿与鳞状肺泡上皮细胞突起的回缩和变性、肺泡上皮细胞表面髓磷脂样“表面活性剂”的丧失以及呼吸迷路的肺不张有关。上皮修复是通过颗粒状肺泡上皮细胞（通常局限于副支气管及其心房）沿漏斗向下迁移并进入呼吸迷路来实现的。尽管鸟类肺部结构与哺乳动物明显不同，但这种损伤和修复模式与哺乳动物的弥漫性肺泡损伤（急性间质性肺炎）相似。本文讨论了这种特殊组织嗜性的意义。
