Warning: file_get_contents(https://eutils.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&id=26664718
&cmd=llinks): Failed to open stream: HTTP request failed! HTTP/1.1 429 Too Many Requests
in C:\Inetpub\vhosts\kidney.de\httpdocs\pget.php on line 215
Deprecated: Implicit conversion from float 213.6 to int loses precision in C:\Inetpub\vhosts\kidney.de\httpdocs\pget.php on line 534
Deprecated: Implicit conversion from float 213.6 to int loses precision in C:\Inetpub\vhosts\kidney.de\httpdocs\pget.php on line 534
Deprecated: Implicit conversion from float 213.6 to int loses precision in C:\Inetpub\vhosts\kidney.de\httpdocs\pget.php on line 534
Deprecated: Implicit conversion from float 213.6 to int loses precision in C:\Inetpub\vhosts\kidney.de\httpdocs\pget.php on line 534
Deprecated: Implicit conversion from float 213.6 to int loses precision in C:\Inetpub\vhosts\kidney.de\httpdocs\pget.php on line 534
Deprecated: Implicit conversion from float 213.6 to int loses precision in C:\Inetpub\vhosts\kidney.de\httpdocs\pget.php on line 534
Deprecated: Implicit conversion from float 213.6 to int loses precision in C:\Inetpub\vhosts\kidney.de\httpdocs\pget.php on line 534
Deprecated: Implicit conversion from float 213.6 to int loses precision in C:\Inetpub\vhosts\kidney.de\httpdocs\pget.php on line 534
Deprecated: Implicit conversion from float 213.6 to int loses precision in C:\Inetpub\vhosts\kidney.de\httpdocs\pget.php on line 534
Deprecated: Implicit conversion from float 247.2 to int loses precision in C:\Inetpub\vhosts\kidney.de\httpdocs\pget.php on line 534
Deprecated: Implicit conversion from float 247.2 to int loses precision in C:\Inetpub\vhosts\kidney.de\httpdocs\pget.php on line 534
Deprecated: Implicit conversion from float 247.2 to int loses precision in C:\Inetpub\vhosts\kidney.de\httpdocs\pget.php on line 534
Deprecated: Implicit conversion from float 247.2 to int loses precision in C:\Inetpub\vhosts\kidney.de\httpdocs\pget.php on line 534
Deprecated: Implicit conversion from float 247.2 to int loses precision in C:\Inetpub\vhosts\kidney.de\httpdocs\pget.php on line 534
Warning: imagejpeg(C:\Inetpub\vhosts\kidney.de\httpdocs\phplern\26664718
.jpg): Failed to open stream: No such file or directory in C:\Inetpub\vhosts\kidney.de\httpdocs\pget.php on line 117 Evodevo
2015 ; 6
(ä): 24
Nephropedia Template TP
gab.com Text
Twit Text FOAVip
Twit Text #
English Wikipedia
Spiralian gastrulation: germ layer formation, morphogenesis, and fate of the
blastopore in the slipper snail Crepidula fornicata
#MMPMID26664718
Lyons DC
; Perry KJ
; Henry JQ
Evodevo
2015[]; 6
(ä): 24
PMID26664718
show ga
BACKGROUND: Gastrulation is a critical step in bilaterian development, directly
linked to the segregation of germ layers, establishment of axes, and emergence of
the through-gut. Theories about the evolution of gastrulation often concern the
fate of the blastopore (site of endomesoderm internalization), which varies
widely in a major branch of bilaterians, the Spiralia. In this group, the
blastopore has been said to become the mouth, the anus, both, or neither.
Different developmental explanations for this variation exist, yet no modern
lineage tracing study has ever correlated the position of cells surrounding the
blastopore with their contribution to tissues of the mouth, foregut, and anus in
a spiralian. This is the first study to do so, using the gastropod Crepidula
fornicata. RESULTS: Crepidula gastrulation occurs by epiboly: the first through
third quartet micromeres form an epithelial animal cap that expands to cover
vegetal endomesodermal precursors. Initially, descendants of the second and third
quartet micromeres (2a-2d, 3a-3d) occupy a portion of the blastopore lip. As the
blastopore narrows, the micromeres' progeny exhibit lineage-specific behaviors
that result in certain sublineages leaving the lip's edge. Anteriorly, cells
derived from 3a(2) and 3b(2) undergo a unique epithelial-to-mesenchymal
transition involving proliferation and a collective movement of cells into the
archenteron. These cells make a novel spiralian germ layer, the ectomesoderm.
Posteriorly, cells derived from 3c(2) and 3d(2) undergo a form of convergence and
extension that involves zippering of cells and their intercalation across the
ventral midline. During this process, several of these cells, as well as the 2d
clone, become displaced posteriorly, away from the blastopore. Progeny of 2a-2c
and 3a-3d make the mouth and foregut, and the blastopore becomes the opening to
the mouth. The anus forms days later, as a secondary opening within the 2d(2)
clone, and not from the classically described "anal cells", which we identify as
the 3c(221) and 3d(221) cells. CONCLUSIONS: Our analysis of Crepidula
gastrulation constitutes the first description of blastopore lip morphogenesis
and fates using lineage tracing and live imaging. These data have profound
implications for hypotheses about the evolution of the bilaterian gut and help
explain observed variation in blastopore morphogenesis among spiralians.