Early Embryonic Development Flashcards
What is a 2 cell morula?
It is an embryo at an early stage. A spherical mass of blastomeres, the first cells of fertilization.
The morula goes through a 2 cell, and a 4 cell stage and continues to divide. At around 80 hours it is called:
An early morula. This is a multi-cell stage.
What does the morula do once it reaches the uterus? What is it called now? And how much time has passed?
1) It begins to take up fluid from it’s surroundings
2) It is now called a blastocyst
3) Around 5 days have passed since fertilization
The wall of the blastocyst consists of:
A single layer of flattened cells (the trophoblast), and an inner cell mass called the embryoblast.
What are the trophoblast cells responsible for?
The attachment of the blastocyst to the uterine epithelium and the implantation into the endometrium.
With implantation, what do the cells of the trophoblast layer do?
They differentiate into a cyto and syncytiotrophoblast and will eventually form the outer embryonic membrane (the chorion) and the fetal portion of the placenta.
The embryo develops from ________ which also contributes to the formation of __________ .
The inner cell mass, called the embryoblast.
The amnion and the yolk sac.
What happens after the two layers form the embryonic disc?
A space appears between the inner cell mass and the trophoblast layer to form the amniotic cavity.
The inner cell mass then divides into ______ ? And these layers form _______ ?
2 layers. The inner layer is called the entoderm, while the outer layer is called the ectoderm.
The embryonic disc.
The amniotic cavity is lined by:
Ectodermal cells of the embryonic disk and amniogenic cells derived from the trophoblast.
The entodermal cells are then separated from the trophoblast by:
The extra embryonic mesoderm.
The cavity of the blastocyst becomes lined on the inside by _______ migrating from __________ to form _____________ .
Entodermal cells
The inner cell mass
The primitive yolk sac.
The embryo proper is now a ________ .
Which will form _______ .
Disc made up of 2 layers of cells
All the intraembryonic tissues
Ectodermal cells migrate between the _____ and the _____ which now gives rise to __________.
Ectoderm and entoderm
The intraembryonic mesoderm, the 3rd layer.
What are the 3 germ layers?
The entoderm, the inside layer. The mesoderm, the middle layer, and the ectoderm, the outer layer.
The entoderm later will help form 1)____, 2)____, and 3)____.
1) Respiratory system 2) Digestive system 3) Bladder
The ______ and ______ are separated by the ______ except at the __________ where the entoderm has thickened. The embryo is now ___ days old.
Ectoderm and entoderm; Mesoderm; Prochordal plate;
20 days old.
The mesoderm later will help form 1) ___, 2) ___, 3) ___, 4) ___, 5) ___, 6) ___, 7) ___.
1) Connective tissue 2) Bone 3) Muscle, including heart & pericardium 4) Vascular system 5) Lymphatic system 6) Kidneys 7) Cartilage
The ectoderm later will help form 1) ___, 2) ___, 3) ___, 4) ___, 5) ___, 6) ___.
1) Skin 2) Hair 3) Nervous system 4) Brain 5) Spine 6) Nails
Mesodermal cells continue to migrate until _____ and _____ are separated from each other by _____ _____, except at the prochordal plate.
Ectoderm and entoderm cells
Intraembryonic mesoderm
The intraembryonic mesoderm has separated the entoderm and ectoderm from each other everywhere except at the _____, which remains bilaminar. This bilaminar part later becomes the _______ _____.
Prochordal plate
Buccopharyngeal membrane
The formation of the celom separates the Mesoderm into two layers: _______ and the _______ .
Splanchnopleuric Mesoderm
Somatopleuric Mesoderm
The Splanchnopleuric Mesoderm is in contact with the ________ .
Endoderm / Entoderm
The Somatopleuric Mesoderm is in contact with the ________ .
Ectoderm
