Click here to close
Hello! We notice that you are using Internet Explorer, which is not supported by Xenbase and may cause the site to display incorrectly.
We suggest using a current version of Chrome,
FireFox, or Safari.
Germline cysts: a conserved phase of germ cell development?
Pepling ME
,
de Cuevas M
,
Spradling AC
.
???displayArticle.abstract???
Germ cells in many vertebrate and invertebrate species initiate gametogenesis by forming groups of interconnected cells known as germline cysts. Recent studies using Xenopus, mouse and Drosophila are beginning to uncover the cellular and molecular mechanisms that control germline cyst formation and, in conjunction with morphological evidence, suggest that the process is highly conserved during evolution. This article discusses these recent findings and argues that cysts play an important and general role in germ line development.
Fig. 1a.
Germline cysts in Drosophila, Xenopus and mouse. (a) Timeline of germ cell development. Germ cells in many species follow a similar path of development. Primordial germ cells increase in number by mitotic division and migrate to the gonad during development. Cyst founder cells (called cystoblasts in the Drosophila females) divide several times followed by incomplete cytokinesis to form a germline cyst of 2n connected cells. In some organisms such as the mouse female, this process occurs only in the embryonic gonad, whereas, in other organisms such as the Drosophila female, this process occurs in the adult gonad. The germ cells then enter meiosis and will eventually develop into mature gametes. (b) Portions of 2–3 germline cysts from a Drosophila ovary stained with VASA antibody (a germ cell marker). (c) A germ cell cluster from a developing Xenopus ovary stained with XGAM antibody, which is specific for gamma-tubulin (image reproduced, with permission, from Ref. 13). (d) Portions of 2–3 germline cysts from a 13.5 days post coitum (dpc) mouse ovary stained with mouse VASA antibody (the antibody was a gift from T. Noce). (e) Portions of 2–3 germline cysts from a Drosophila testis stained with VASA antibody. (f) Part of a germline cyst from a mouse testis stained with mouse VASA antibody. Top insets (b–d) and insets (e) and (f) are electron micrographs from each species showing an intercellular bridge (arrows) connecting two germ cells (images reproduced, with permission, from 3; 10 ; 51; bar, 1 μm). Bottom insets (b–d) show the mitotic synchrony of cyst-forming divisions from each species (images reproduced, with permission, from 11; 13 ; 19). All the electron micrographs are presented at the same magnification. Note the similarity in size of the ring canals in different species. Bars in (b) [for (b) and (e)] and (d) [for (d) and (f)], 10 μm.
Fig. 2a,b.
Organelle aggregates in cyst-forming cells. (a) Drawing of a dividing cystoblast from the ovary of the water beetle Dytiscus (originally from Ref. 52; this image was redrawn in Ref. 53). The fusome (F) and an oocyte-specific ring of rDNA (R) segregate to the same cell at cytokinesis. (b) A round fusome shown in red (arrow) in a dividing Drosophila germ cell (image reproduced, with permission, from Ref. 24). (c) Two mouse germ cells from a 10.5 days post coitum (dpc) mouse genital ridge stained with EMA, a germ cell marker labelling a sphere in the cytoplasm. (d) One oocyte from a 16-cell Xenopus nest that shows the location of the mitochondrial cloud precursor (arrow) and the nucleus (N; image reproduced, with permission, from Ref. 23). Bars, 8 μm.
