The reason why gastrulation is so important is because gastrulation establishes the fundamental body plan, which creates the 3 primary germ layers, which are the ectoderm, mesoderm and endoderm, which is what forms the tissues and organs in the body, and also defines the main body axes, of head to tail and back to belly.
This is a cellular rearrangement that transforms a simple cell ball into a multi layered, directional embryo, setting the stage for development of complex organs also known as organogenesis as well as survival, with failures often leading to birth defects or miscarriages.
The key functions of gastrulation are the formation of the germ layers, as it reorganizes cells into 3 distinct layers, each destined to become specific organs and tissues and the ectoderm forms the nervous system, brain spinal cord and skin and mesoderm develops into muscles, skeleton, circulatory system and reproductive organs and the endoderm gives rise to the digestive tract lining, liver, pancreas and the lungs.
Body Axis establishment defines the anterior-posterior head to tail and dorsal-ventral (back to belly) axes, giving the embryo it's shape and direction.
Internal structure formation positions precursors for internal organs and surrounds them with protective skin cells and foundation for Organogenesis provides the organized cellular framework that is necessary for subsequent formation of all the complex organs.
Without gastrulation, the embryo lacks direction and organized layers, which makes complex development impossible.
And it's a delicate process, and errors can result in severe congenital anomalies or even failure to implant, explaining many early pregnancy losses.
And understanding of gastrulation also helps to explain birth defects and provides insights for regenerative medicine, like stem cell therapies.
The three layers of the embryonic disc are the ectoderm or outer layer, the mesoderm middle layer and the endoderm inner layer, which then all differentiate to form all tissues and organs within the body.
The three parts of the embryonic disc are the germ layers, which are the ectoderm, which is what forms the skin and the nervous system, the mesoderm, which gives rise to muscles, bones and the circulatory system and the endoderm, which develops into the lining of the digestive tract, lungs, liver and the pancreas.
These three parts or three layers of the embryonic disc establish the foundation of all the tissues and organs in the body.
The ectoderm, develops into the epidermis or outer skin, nervous system, brain, spinal cord, nerves, hair, nails and tooth enamel.
The mesoderm forms muscles, skeleton, bone, cartilage, connective tissues, circulatory system, heart, blood vessels, kidneys, gonads, and the dermis of the skin.
And the endoderm creates the epithelial lining of the digestive and respiratory tracts, liver, pancreas, thyroid, bladder and also parts of the reproductive system.
Another name for the embryonic disc is "embryonic shield" which is also known as the blastoderm.
The embryonic shield or embryonic disc or blastoderm is the foundational structure, from which the actual embryo develops from.
An embryonic disc is a flattened, plate like structure in the early embryo.
The embryonic disc in the early embryo is initially two layered also called bilaminar and later the embryonic disc becomes three layered also known as trilaminar.
The embryonic disc is formed from the inner cell mass, from which the actual fetus develops, differentiating into all the body's tissues and organs.
An embryonic disc sits between the amniotic cavity above and the yolk sac below, with the top layer called the epiblast giving rise to the embryo proper, and the lower layer called the hypoblast forming the yolk sac.
The key stages and layers of the embryonic disc are the bilaminar disc, in week 2, which is formed by the inner cell mass into 2 layers.
The epiblast or upper, which is the columnar cells that will form the embryo.
And the hypoblast or lower, which is the cuboidal cells forming the primitive yolk sac.
In week 3, gastrulation occurs, in which the epiblast folds inwards and creates a third layer also known as mesoderm and forms the trilaminar disc.
Then the trilaminar disc, which is 3 layers, is the ectoderm from the epiblast, which becomes skin, brain and nervous system.
Mesoderm, the new layer, which forms muscles, skeleton, circulatory system, etc.
And the endoderm, from the epiblast/hypoblast, develops into the lining of the gut, lungs and other organs.
The significance of the embryonic disc is the foundation, orientation and folding.
The embryonic disc is the source of all cells for the developing organism.
The formation of the primitive streak on the disc establishes the body's head to tail axis.
And the embryonic disc also undergoes folding to create the 3 dimensional body plan of the embryo, forming the anterior body all and gut tube.