English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

Cell lineage studies in mollusk embryos have documented numerous variations on the lophotrochozoan theme of spiral cleavage. In the experimentally tractable embryo of the mud snail  Ilyanassa,  cell lineage has previously been described only up to the 29-cell stage. Here I provide a chronology of cell divisions in  Ilyanassa  to the stage of 84 cells (about 16 hours after first cleavage at 23°C), and show spatial arrangements of identified nuclei at stages ranging from 27 to 84 cells. During this period the spiral cleavage pattern gives way to a bilaterally symmetric, dorsoventrally polarized pattern of mitotic timing and geometry. At the same time, the mesentoblast cell 4d rapidly proliferates to form twelve cells lying deep to the dorsal ectoderm. The onset of epiboly coincides with a period of mitotic quiescence throughout the ectoderm. As in other gastropod embryos, cell cycle lengths vary widely and predictably according to cell identity, and many of the longest cell cycles occur in small daughters of highly asymmetric divisions. While  Ilyanassa  shares many features of embryonic cell lineage with two other caenogastropod genera,  Crepidula  and  Bithynia,  it is distinguished by a general tendency toward earlier and more pronounced diversification of cell division pattern along axes of later differential growth.

Cell Lineage of the Ilyanassa Embryo: Evolutionary Acceleration of Regional Differentiation during Early Development