FINE STRUCTURE AND REPRODUCTION OF TOXOPLASMA GONDII
FINE STRUCTURE AND REPRODUCTION OF TOXOPLASMA GONDII
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DOI：
10.2307/3276925
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发表时间：
1968-01-01
影响因子：
1.3
通讯作者：
MELTON, ML
中科院分区：
文献类型：
--
作者：
SHEFFIELD, HG;MELTON, ML
弓形虫在宿主细胞的液泡内发育。寄生虫呈新月形，但在分裂前变得更圆。它被由外膜和下面的内膜组成的薄膜包围。后者在生物体周围是连续的，除了前端开口周围的轻微增厚（极环）和后端的类似增厚之外。膜下原纤维在增厚层之间纵向延伸。珠孔位于核前缘附近的侧面。圆锥体位于极环内部生物体的前端。几个棒状的成对细胞器位于细胞质中，它们的颈部延伸到圆锥体中。小的弯曲杆状结构（微线体）通常存在于前端。高尔基体区位于细胞核的前面，细胞核位于生物体的后半部。细胞质中随机分布着众多的核糖体、粗面内质网和一到几个线粒体。弓形虫通过内生分裂进行分裂，其中由母细胞形成 2 个子细胞。分裂的早期迹象是高尔基体区域分为两部分以及高尔基体附属物的出现。随后，每个子体的内膜前部在其高尔基区附近形成。当内膜的后端围绕已成为马蹄形的细胞核延伸时，前端细胞器在膜封闭区域内形成。然后细胞核分裂，每个部分都被生长的子膜包围。子代的持续生长导致母体细胞质的同化。母细胞内膜消失，其外膜包围子细胞，但子细胞之间的区域除外，其中新的外膜是通过母细胞细胞质区域中出现的囊泡融合形成的，该囊泡将两个子细胞内膜分开。当连续分裂发生但后代后端没有分离时，通常会出现莲座丛。
T. gondii develops within a vacuole of the host cell. The parasite is crescent-shaped but becomes somewhat rounder prior to division. It is enclosed by a pellicle consisting of an outer membrane and an underlying inner membrane. The latter is continuous around the organism except for a slight thickening (polar ring) surrounding an opening at the anterior end and similar thickening at the posterior end. Subpellicular fibrils extend longitudinally between the thickenings. A micropyle is situated laterally near the anterior edge of the nucleus. The conoid is found at the anterior end of the organism just inside the polar ring. Several club-shaped paired or-ganelles lie in the cytoplasm with their necks extending into the conoid. Small curved rodlike structures (micronemes) are usually present in the anterior end. The Golgi area is just anterior to the nucleus which is in the posterior half of the organism. Numerous ribosomes, rough endoplasmic reticulum, and one to several mitochondria are randomly distributed in the cytoplasm. T. gondii divides by endodyogeny wherein 2 daughter cells are formed from a mother cell. Early indications of division are the separation of the Golgi area into 2 parts and the appearance of the Golgi adjunct. Later, the anterior portion of the inner membrane of each daughter forms adjacent to its Golgi area. Anterior end organelles form within the membrane-enclosed area as the posterior ends of the inner membranes extend around the nucleus which has become horseshoe-shaped. The nucleus then divides with each portion being enclosed by the growing daughter membrane. Continued growth of the daughters results in assimilation of the mother cytoplasm. The mother cell inner membrane disappears and its outer membrane encloses the daughter cell except in the region between the daughters where new outer membrane is formed by fusion of vesicles appearing in the area of mother cell cytoplasm which separates the 2 daughter cell inner membranes. Rosettes often occur when successive divisions take place without separation of the posterior ends of the offspring.