AUTHOR=Funakoshi Haruka M. , Shito Takumi T. , Oka Kotaro , Hotta Kohji 

TITLE=Developmental Table and Three-Dimensional Embryological Image Resource of the Ascidian Ascidiella aspersa

JOURNAL=Frontiers in Cell and Developmental Biology

VOLUME=9

YEAR=2021

URL=https://www.frontiersin.org/journals/cell-and-developmental-biology/articles/10.3389/fcell.2021.789046

DOI=10.3389/fcell.2021.789046

ISSN=2296-634X

ABSTRACT=<p><italic>Ascidiella aspersa</italic> is an ascidian in the class of chordates—the closest relatives of vertebrates. <italic>A</italic>. <italic>aspersa</italic> is a potential model organism for bio-imaging studies due to its extremely transparent embryos as well as is a globally distributed cosmopolitan species. However, there is no standard developmental table for this organism. Here, as a first step to establish <italic>A</italic>. <italic>aspersa</italic> as a model organism, we report a standard developmental table as a web-based digital image resource. This resource used confocal laser scanning microscopy to scan more than 3,000 cross-sectional images and 3D-reconstructed images of <italic>A</italic>. <italic>aspersa</italic> embryos during embryogenesis. With reference to the standardized developmental table of <italic>Ciona intestinalis</italic> type A, 26 different developmental stages (Stages 1–26) from fertilized eggs to hatched larvae were redefined for <italic>A</italic>. <italic>aspersa</italic>. Cell lineages up to the cleavage period were annotated: The cleavage patterns, the embryonic morphology, and the developmental time were then compared with <italic>Ciona</italic>. We found that the cleavage patterns and developmental time up to the neurula period in <italic>A</italic>. <italic>aspersa</italic> were extremely conserved versus. <italic>Ciona</italic>. The ratio of the trunk and tail length in the tailbud period were smaller than <italic>Ciona</italic> indicating a relatively short tail. In addition, the timing of the bending of the tail is earlier than <italic>Ciona</italic>. This <italic>A</italic>. <italic>aspersa</italic> standard 3D digital resource is essential for connecting different omics data to different spatiotemporal hierarchies and is useful for a system-level understanding of chordate development and evolution.</p>