A trilaminar embryonic disc
(or trilaminary blastoderm, or trilaminar germ disk) is an early stage in the development of
triploblastic
Triploblasty is a condition of the gastrula in which there are three primary germ layers: the ectoderm, mesoderm, and endoderm. Germ cells are set aside in the embryo at the blastula stage, which are incorporated into the gonads during organo ...
organisms, which include humans and many other animals. It is the next stage from the earlier
bilaminar embryonic disc.
It is an embryo which exists as three different
germ layers - the
ectoderm, the
mesoderm and the
endoderm. These
layers are arranged on top of each other, giving rise to the name ''trilaminar'', or "three-layered". The mesoderm is segmented further into the paraxial, intermediate and the lateral plate mesoderm.
These three layers arise early in the third week (during
gastrulation) from the
epiblast
In amniote embryonic development, the epiblast (also known as the primitive ectoderm) is one of two distinct cell layers arising from the inner cell mass in the mammalian blastocyst, or from the blastula in reptiles and birds, the other laye ...
(a portion of the mammalian
inner cell mass).
References
External links
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*
Overview at edu.mt
Embryology
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