SALIVARY-GLAND OF THE TICK VECTOR OF EAST COAST FEVER .4. CELL TYPE SELECTIVITY AND HOST-CELL RESPONSES TO THEILERIA-PARVA
SALIVARY-GLAND OF THE TICK VECTOR OF EAST COAST FEVER .4. CELL TYPE SELECTIVITY AND HOST-CELL RESPONSES TO THEILERIA-PARVA
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DOI：
10.1016/0040-8166(82)90035-0
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发表时间：
1982-01-01
期刊：
影响因子：
2.6
通讯作者：
DOXSEY, S
中科院分区：
文献类型：
--
作者：
FAWCETT, DW;BUSCHER, G;DOXSEY, S
用电镜研究了蜱唾液腺细胞对细小t虫寄生的反应。唾液腺由3种不同类型的腺泡（I， II， III）组成，共包括10种或更多不同的细胞类型。在本研究中观察到的约30个感染细胞中，均为腺泡ⅲ型e细胞。该寄生虫对腺泡和细胞类型具有高度的选择性。被侵染的腺细胞大量肥大，并在细胞质中积累糖原沉积物，为细胞内寄生虫的生长提供能量。随着其分泌物质的合成下降，该产品被包装在逐渐变小的分泌颗粒中。广泛排列的内质网在自噬液泡中被拆除和消除。过量的分泌颗粒也会被吞噬。4天后，孢子形成完成，寄主细胞在基本没有细胞膜和分泌颗粒的电子透光细胞质中含有30,000-50,000个孢子体。线粒体仍然存在，外观正常。到目前为止，通过光镜观察到的嗜碱性细胞和分泌颗粒的损失归因于寄生虫摄入和破坏宿主细胞器。细胞质的苍白外观被解释为宿主细胞即将退化的迹象。在电子显微镜下，没有发现寄生虫摄取细胞器或退化变化。宿主细胞在整个孢子形成过程中保持活力和代谢活性。其超微结构的变化是由于寄主细胞自身对寄生的主动清除细胞器和包涵体所致。
Responses of cells in the tick salivary gland to parasitism by T. parva were studied by EM. The gland is composed of 3 distinct types of acini (I, II, III) which together include 10 or more different cell types. Of some 30 infected cells observed in the present study, all were E-cells of acinus III. The parasite exhibits a high degree of selectivity for acinus and cell type. The glandular cell invaded undergoes massive hypertrophy and accumulates glycogen deposits in its cytoplasm which may serve as an energy source for the growing intracellular parasite. As synthesis of its secretory material declines, the product is packaged in progressively smaller secretory granules. The extensive arrays of endoplasmic reticulum are dismantled and eliminated in autophagic vacuoles. Excess secretory granules are also broken down by crinophagy. After 4 days, sporogony is completed and the host cell contains 30,000-50,000 sporozoties in an electron-lucent cytoplasm largely devoid of cytomembranes and secretory granules. Mitochonria are still present and normal in appearance. The loss of basophilia and secretory granules observed heretofore by light microscopy have been attributed to ingestion and destruction of host organelles by the parasite. The pallid appearance of the cytoplasm was interpreted as a sign of impending degeneration of the host cell. In electron micrographs, no ingestion of organelles by the parasite or degnerative changes were found. The host cell remains viable and metbolically active throughout sporogony. The changes in its ultrastructure result from active elimination of organelles and inclusions by the host cell itself in response to parasitism.