This is the first report that describes histological and ultrastructural details of ovary organization in haemadipsid leeches. In Haemadipsa japonica, the female reproductive system is organized similar to that of other haemadipsids. Each of the paired and oval ovaries of H. japonica is comprised of the ovary wall (ovisac), which encloses two elongated, thread-like ovarian units termed ovary cords. Ovary cords are comprised of germ-line cells and associated somatic cells. Each cord is polarized and contains germ-line cells in the consecutive developmental stages that are sequentially located along the long cord axis. There were three zones in each cord: the club-shaped apical part, the thread-like middle part, and the basal-most end, which contains degenerating germ cells. Outside of the reproductive period, the middle part of the cord in leeches is smooth, and no growing oocytes are visible; alternatively, in mature specimens, several growing oocytes protrude from the cord, and several huge vitellogenic oocytes that are completely detached from the cord occur within the ovisac. Ovary cord organization and functioning in H. japonica are very similar to the ‘Hirudo’ type cords that were found in several hirudiniform leeches. This conclusion supports the view that all hirudiniform leeches have conservative ovary cord organization and a similar pattern of oogenesis. Germ-line cyst composition, architecture, and functioning were also found to be evolutionarily conservative characteristics when compared with all previously examined Clitellata. In the germ-line cysts found in H. japonica each cell is connected to the central and anuclear cytoplasmic mass (cytophore) via one intercellular bridge, and, as oogenesis progresses, the fate of interconnected cell diversifies: some of them (oocytes) grow and complete oogenesis, but the majority become nurse cells and finally degenerate. Thus, oogenesis in H. japonica, similar to other clitellates, can be considered meroistic.

这是描述血吸虫水蛭卵巢组织的组织学和超微结构细节的第一份报告。在Haemadipsa japonica 中，雌性生殖系统的组织与其他 haemadipsid 相似。H. japonica 的每个成对和椭圆形卵巢由卵巢壁 (ovisac) 组成，它包围着两个细长的线状卵巢单位，称为卵巢索。卵巢索由生殖系细胞和相关的体细胞组成。每根脐带都是极化的，并且包含处于连续发育阶段的生殖系细胞，这些细胞沿着脐带长轴顺序排列。每条脐带中有三个区域：棒状的顶端部分、线状的中间部分和最基端，其中包含退化的生殖细胞。生殖期外，水蛭脐带中部光滑，未见生长卵母细胞；或者，在成熟的标本中，几个正在生长的卵母细胞从脐带中突出，并且在卵囊内出现了几个与脐带完全分离的巨大卵母细胞。卵巢索的组织和功能H. japonica与在几种水蛭形水蛭中发现的“水蛭”型线非常相似。这一结论支持所有水蛭都具有保守的卵巢索组织和类似的卵子发生模式的观点。与所有先前检查的 Clitellata 相比，还发现种系囊肿的组成、结构和功能在进化上是保守的特征。在H. japonica 中发现的种系囊肿中，每个细胞通过一个细胞间桥连接到中央和无核细胞质团块（细胞团），并且随着卵子发生的进展，相互连接的细胞的命运多样化：其中一些（卵母细胞）生长并完成卵子发生，但大多数成为护理细胞并最终退化。因此，卵子发生在H. japonica，类似于其他的clitellates，可以被认为是meroistic。