The development of oocytes in the ovary of a parthenogenetic tick, Haemaphysalis longicornis
The development of oocytes in the ovary of a parthenogenetic tick, Haemaphysalis longicornis
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DOI：
10.1016/j.parint.2018.04.006
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发表时间：
2018-08-01
影响因子：
1.9
通讯作者：
Suzuki, Hiroshi
中科院分区：
文献类型：
--
作者：
Mihara, Ryo;Umemiya-Shirafuji, Rika;Suzuki, Hiroshi
长角血蜱是家畜和人类多种病原体的重要载体。蜱是一种独特的物种，具有双性和孤雌生殖种族。尽管交配会诱导卵母细胞发育，但在孤雌生殖种族中，无需交配即可完成卵子发生。在这里，我们研究了单性生殖长角雉的卵母细胞从未进食到产卵期的发育过程。我们将卵母细胞的发育阶段分为五个阶段：I阶段，生发囊泡占据细胞质的一半以上； II期，生发囊泡占细胞质的一半以下；第三阶段，生发囊泡从卵母细胞中心迁移到蒂细胞附近； IV期，细胞质充满各种大小的卵黄颗粒；第五阶段，细胞质被大卵黄颗粒占据。未喂养期的卵母细胞未发育，属于I期。快速喂养期观察到I期和II期卵母细胞，表明卵母细胞在开始血液喂养后开始发育。在产卵前期观察卵母细胞的所有发育阶段。产卵期开始后10天，I期和II期卵母细胞的比例高于前期，表明卵巢的发育和活性可能仍在持续。基于这些发现，我们提出了孤雌长角长角虫卵母细胞发育的分类标准。该标准将有助于了解蜱繁殖和病原体经卵巢传播的机制。
Haemaphysalis longicornis is an important vector of various pathogens in domestic animals and humans. The tick is a unique species with bisexual and parthenogenetic races. Although mating induces oocyte development, it is possible in the parthenogenetic race to complete oogenesis without copulation. Here we examined the developmental process of oocytes from unfed to the oviposition period in parthenogenetic H. longicornis. We classified the developmental stages of oocytes into five stages: stage I, germinal vesicle occupies more than half of the cytoplasm; stage II, germinal vesicle occupies less than half of the cytoplasm; stage III, germinal vesicle migrates from the center in the oocyte to the vicinity of the pedicel cells; stage IV, the cytoplasm is filled with yolk granules of various sizes; stage V, the cytoplasm is occupied by large yolk granules. Oocytes at the unfed period were undeveloped and classified as stage I. Stage I and II oocytes were observed at the rapid feeding period, indicating that oocyte development began after the initiation of blood feeding. All developmental stages of oocytes were observed at the pre-oviposition period. At 10 days after the beginning of the oviposition period, the ratios of stage I and II oocytes were higher than those of the previous period, suggesting that the ovarian development and activity may be continuing. Based on these findings, we propose classification criteria for the oocyte development in the parthenogenetic H. longicornis. The criteria will be useful for understanding the mechanisms of tick reproduction and transovarial transmission of pathogens.