Egg development is a defining process of reproduction in higher eukaryotes. In the fruit fly, Drosophila melanogaster, this process begins with four mitotic divisions starting from a single germ cell, producing a cyst of 16 cystocytes; one of these cells will become the oocyte and the others supporting nurse cells. These mitotic divisions are exceptional because cytokinesis is incomplete, resulting in the formation of cytoplasmic bridges known as ring canals that interconnect the cystocytes. This organization allows all cystocytes to divide synchronously during each mitotic round, resulting in a final, power-of-2 number of germ cells. Given that numerous insects obey this power-of-2 rule, we investigated if strict cell doubling is a universal, underlying cause. Using confocal microscopy, we found striking departures from this paradigm in three different power-of-2 insects belonging to the Apocrita suborder (ants, bees and wasps). In these insects, the earliest-formed cystocytes cease to divide during the latter mitotic cycles while their descendants undergo further division, thereby producing a 'radial' direction of division activity. Such cystocyte division patterns that depart from strict cell doubling may be 'fine-tuned' in order to maintain a final, power-of-2 germ cell number.

中文翻译：

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膜翅目昆虫卵生产中生殖细胞分裂的新模式。

卵的发育是高等真核生物繁殖的决定性过程。在果蝇果蝇中，此过程从单个生殖细胞开始，经历了四个有丝分裂分裂，产生了16个囊状细胞的囊肿。这些细胞之一将成为卵母细胞，其他细胞将成为护士细胞。这些有丝分裂分裂是异常的，因为胞质分裂是不完全的，导致形成胞质桥，称为环管，该环管将囊胞相互连接。这种组织允许所有的囊细胞在每个有丝分裂回合中同步分裂，从而产生最终的2幂的生殖细胞。鉴于许多昆虫都遵循2幂定律，我们研究了严格的细胞倍增是否是普遍的根本原因。使用共聚焦显微镜，我们发现属于这种模式的是与Apocrita子亚目（蚂蚁，蜜蜂和黄蜂）有关的三种不同的2次幂的昆虫显着不同。在这些昆虫中，最早形成的囊细胞在后一个有丝分裂周期中停止分裂，而其后代进一步分裂，从而产生“放射状”的分裂活动方向。可以对这种偏离严格的细胞倍增的细胞分裂模式进行“微调”，以维持最终的2次幂的生殖细胞数量。