The process that occurs after cleavage in which the cells differentiate and the embryoblast gravitate towards one extreme of the now formed blastocyst.
After blastocyst formation & zona pellucida disintegration, what occurs?
The embryoblast begin form a cavity known as the amniotic cavity; below this cavity the embryoblast have further divided into two distinct layers: the epiblast (closest to amniotic cavity), and the hypoblast (below the epiblast).
The dual layer formed by the epiblast and hypoblast
Inner Cell Mass
The mass that forms whenever the embryoblasts clump together and cluster towards one side of the developing structure.
From what end does the primitive streak form?
It forms from the caudal end of the bilaminar embryonic disk.
What the path of migration for the epiblast cells?
They begin by migrating towards the primitive streak and then burrowing their way down into the bilaminar disk.
Once the morula forms, what occurs to the cells within the zona pellucida?
Once the morula forms, the cell begin to get closer and closer together in a process known as compaction; in addition, the cells start to differentiate into two layers known as the trophoblast (outer layer cells) and embryoblast (inner layer cells).
Once the three layers are formed (trilaminar disk), what is the next step after gastrulation?
What is the next step after the formation of the blastocyst?
The complete disintegration of the zona pellucida
Forms whenever the zygote successfully cleaves into 32 cells.
What occurs during the initial stages of embryogenesis?
The sperm and egg merge to form a zygote, then the zygote divides without growth (clevage) until a morula is formed (32 cells).
What does the notochord induce?
It induces a change through the release of morphogenetic factors in the ectoderm above it: a thickening which leads to the formation of the neural plate.
Thick outer glycoprotein coat found in egg cells
Site on the bilaminar disk where the epiblast begin to migrate
What marks the beginning of gastrulation?
The formation of the primitive streak on the epiblast layer.
Within what structure is the morula still contained?
The cell are still stuck under the zona pellucida
The cavity formed whenever the embryoblast cluster towards one end of the developing structure.
What does the migration of the epiblast cells accomplish?
As the epiblast migrate into the body of the bilaminar disk, they differentiate into a middle layer; this create a trilaminar disk with the epiblast forming the ectoderm, the new middle layer forming the mesoderm, and the hypoblast forming the endoderm.
What occurs at the cranial end of the embryonic streak?
The primitive streak expands to form the primitive node with a depression called the primitive pit.
What happens after the neural plate is formed?
The neural plate begin to dive into the mesoderm and zip close forming a tube structure (neural tube).
Process of splitting without growth in embryogenesis
When does the zona pellucida begin to desintegrate?
Around the stage of the formation of the blastocyst the zona pellucida begins to degrade.
The cellular structure formed whenever a sperm merges with an egg – genetic material also merges.
Area of the mesoderm below the primitive streak that begins to differentiate into a chord like structure. It does form part of the invertebral disc and very rarely does cause a tumor called a chordoma, but its main function in humans is in neurolation.
What happens to the cluster of embyoblast after they differentiate from trophoblast?
The cells within the embryoblast begin to clump together more and more, clustering towards one end of the structure – leaving a cavity on the other end.