Trilaminar blastocyst

A trilaminar embryo (or trilaminary blastoderm, or trilaminar germ disk) is an early stage in the development of triploblastic organisms, which include humans and many other animals.

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 like a stack of paper, giving rise to the name trilaminar, or "three-layered".

These three layers arise early in the third week (after gastrulation) from the epiblast (a portion of the mammalian inner cell mass).

External links

Swiss embryology (from UL, UB, and UF) hdisqueembry/triderm01
Embryology at UNSW Notes/week3_4
Overview at edu.mt

Human embryogenesis in the first three weeks

Week 1

Week 2
(Bilaminar)

Week 3
(Trilaminar)

Germ layers	Archenteron/Primitive streak Primitive pit Primitive knot/Blastopore Primitive groove Gastrula Gastrulation Regional specification Embryonic disc

Ectoderm	Surface ectoderm Neuroectoderm Somatopleuric mesenchyme Neurulation Neural crest

Endoderm	Splanchnopleuric mesenchyme

Mesoderm	Axial mesoderm Paraxial Somite Somitomere Intermediate Lateral plate Intraembryonic coelom Splanchnopleuric mesenchyme Somatopleuric mesenchyme

Index of developmental medicine

Description	Embryology Cell lines

Disease

Categories

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Trilaminar blastocyst