Early female germline development in Xenopus laevis: Stem cells, nurse cells, and germline cysts

• 成果类型: Article
• 署名作者: Davidian, Asya; Spradling, Allan C.
• 署名单位: Howard Hughes Medical Institute; Carnegie Institution for Science
• 刊物名称: PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
• ISSN/ISSBN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.2522343122
• 发表日期: 2025-11-18
• 页码: e2522343122
• 关键词: Xenopus; ovary; germ cell; germline stem cell; germline cyst; BALBIANI BODY; PREVITELLOGENIC OOCYTES; EARLY OOGENESIS; mouse; dna; expression; mitochondria; polarity; meiosis; OOGONIA

摘要

In Drosophila, germline cysts arise through synchronous mitotic divisions and acquire a polarized architecture organized by the fusome, which guides oocyte specification and supports meiotic progression. Similar cyst structures exist in nonmammalian vertebrate ovaries, but their polarity and function have remained uncertain. Using single-cell RNA sequencing and high-resolution imaging, we reconstructed the germ cell differentiation trajectory in Xenopus laevis and uncovered striking parallels with invertebrate and mouse cyst development. We identified a distinct germline stem cell (GSC) population marked by piwil4, low translational activity, and expression of neuronal-specific and transposon-silencing genes. Downstream from GSCs, during cyst development, an asymmetric fusome-like structure composed of stable microtubules forms a rosette-like connection between cystocytes and contains Golgi vesicles and endoplasmic reticulum, suggesting polarized trafficking. In contrast to previous claims, similar to 80% of cyst cells turned over rather than forming oocytes, consistent with a nurse cell fate. The striking parallels described here between cyst and fusome formation, polarization, cyst breakdown, and nurse-like cell turnover to produce relatively few oocytes argue that amphibian cysts have important functions in female gametogenesis.