Laboratory of Physiology, A.V. Zhirmunsky National Scientific Center of Marine Biology, Far Eastern Branch, Russian Academy of Sciences, Vladivostok, Primorsky Krai, Russia.
Department of Fisheries, Wildlife and Conservation, Oregon State University, Newport, Oregon, United States of America.
PeerJ. 2022 Mar 10;10:e12950. doi: 10.7717/peerj.12950. eCollection 2022.
Females of the gammaridean amphipod with signs of regenerating, previously atrophied ovaries were recovered from the northeastern shelf of Sakhalin Island (Okhotsk Sea, Russia). Ovarian regeneration was previously unknown for any amphipod species. have a predominantly 2-year life cycle (from embryo to adult death) and reproduce once between late winter or early spring at the age of 2 years. Occasionally, females survive to a third year. An adaptive value of extended survival among these females is likely to require that they are also reproductive.
Histological sections from a second-year female with ovarian atrophy, a female with normal ovaries, a third-year female with ovarian regeneration, as well as testes of an immature and a sexually mature male were compared to determine the sources of cells of the germinal and somatic lines necessary for ovarian regeneration.
Ovarian regeneration in the third-year female began with the formation of a new germinal zone from germ cells preserved in the atrophied ovaries and eosinophilic cells of the previously starving second-year female. Eosinophilic cells form the mesodermal component of the germinal zone. A mass of these cells appeared in the second-year female that had atrophied ovaries and in large numbers on the intestine wall of the third-year female with regenerating ovaries. These eosinophilic cells appear to migrate into the regenerating ovaries.
All germ cells of the second-year female are not lost during ovarian atrophy and can be involved in subsequent ovarian regeneration. Eosinophilic cells involved in ovarian regeneration are of mesodermal origin. The eosinophilic cell morphologies are similar to those of quiescence cells (cells in a reversible state that do not divide but retain the ability to re-enter cell division and participate in regeneration). These histological data thus indicate that eosinophilic and germ cells of third-year females can participate in the regeneration of the ovaries to reproduce a second brood. The precursors of these third-year females (a small number the second-year females with an asynchronous [summer] breeding period and ovaries that have atrophied due to seasonal starvation) appear to possess sources of somatic and germ cells that are sufficient for ovarian regeneration and that may be adaptations to starvation stress.
在萨哈林岛东北部大陆架（鄂霍次克海，俄罗斯）发现了有再生迹象、先前萎缩的卵巢的端足目桡足类雌性个体。以前，任何一种桡足类物种都没有卵巢再生现象。它们的生命周期主要为 2 年（从胚胎到成年死亡），并在 2 岁时的冬末或早春进行一次性繁殖。偶尔，雌性个体也能存活到第 3 年。这些雌性个体延长生存的适应价值可能需要它们也具有生殖能力。
比较了一只第二年卵巢萎缩的雌性个体、一只卵巢正常的雌性个体、一只第三年卵巢再生的雌性个体以及一只未成熟和一只性成熟雄性个体的组织切片，以确定卵巢再生所需的生殖系和体系细胞的来源。
第三年雌性个体的卵巢再生始于从保存在萎缩卵巢中的生殖细胞和前一年饥饿的第二年雌性个体的嗜酸性细胞中形成新的生殖区。嗜酸性细胞形成生殖区的中胚层成分。大量的这些细胞出现在第二年卵巢萎缩的雌性个体中，并在第三年卵巢再生的雌性个体的肠壁上大量出现。这些嗜酸性细胞似乎迁移到再生的卵巢中。
第二年雌性个体的所有生殖细胞在卵巢萎缩过程中并未丢失，并且可以参与随后的卵巢再生。参与卵巢再生的嗜酸性细胞来源于中胚层。嗜酸性细胞的形态与静止细胞（处于可逆状态的细胞，它们不分裂，但保留重新进入细胞分裂并参与再生的能力）的形态相似。这些组织学数据表明，第三年雌性个体的嗜酸性细胞和生殖细胞可以参与卵巢的再生，以繁殖第二窝后代。这些第三年雌性个体的前体（少数第二年雌性个体，它们具有异步[夏季]繁殖期，并且由于季节性饥饿而使卵巢萎缩）似乎拥有足够的体系和生殖细胞来源，用于卵巢再生，这可能是对饥饿压力的适应。
