gastrula
n . 胚囊,肠胚
胚囊,肠胚
gastrula n 1 :
double -
walled stage of the embryo resulting from invagination of the blastula ;
the outer layer of cells is the ectoderm and the inner layer differentiates into the mesoderm and endoderm Gastrula \
Gas "
tru *
la \,
n .;
pl . {
Gastrul [
ae ]}[
NL .,
dim .
fr .
Gr . ?
the stomach .] (
Biol .)
An embryonic form having its origin in the invagination or pushing in of the wall of the planula or blastula (
the blastosphere )
on one side ,
thus giving rise to a double -
walled sac ,
with one opening or mouth (
the blastopore )
which leads into the cavity (
the archenteron )
lined by the inner wall (
the hypoblast ).
See Illust .
under {
Invagination }.
In a more general sense ,
an ideal stage in embryonic development .
See {
Gastr [
ae ]
a }. --
a .
Of or pertaining to a gastrula .
[
1913 Webster ]
Planula \
Plan "
u *
la \,
n .;
pl . {
Planul [
ae ]}. [
L .,
a little plane .]
1 . (
Biol .)
In embryonic development ,
a vesicle filled with fluid ,
formed from the morula by the divergence of its cells in such a manner as to give rise to a central space ,
around which the cells arrange themselves as an envelope ;
an embryonic form intermediate between the morula and gastrula .
Sometimes used as synonymous with {
gastrula }.
[
1913 Webster ]
2 . (
Zool .)
The very young ,
free -
swimming larva of the c [
oe ]
lenterates .
It usually has a flattened oval or oblong form ,
and is entirely covered with cilia .
[
1913 Webster ]
Stomapoda \
Sto *
map "
o *
da \,
n .
pl . [
NL .
See {
Stoma },
and {-
poda }.]
(
Zool .)
An order of Crustacea including the squillas .
The maxillipeds are leglike in form ,
and the large claws are comblike .
They have a large and elongated abdomen ,
which contains a part of the stomach and heart ;
the abdominal appendages are large ,
and bear the gills .
Called also {
Gastrula }, {
Stomatopoda },
and {
Squilloidea }.
[
1913 Webster ]
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