Embryology: Conception to Zygote Formation Flashcards
Phase of reproduction where two haploid sex cells fuse What do they form?
Fertilization
Zygote
The vaginal canal is BASIC/ACIDIC
Prostate gland produces alkanine or acidic sustenances for the semen to protect it?
Acidic
Alkaline
In addition to mature, fully motile sperm and unobstructed female reproductive tract, 2 other things are required for successful fertilization
Capacitation
Acrosome Reaction
This is the process in fertilization tha ttallows sperm to become mobile enough to attach to cells on the oocyte
It happens in where?
Capacitation
Uterine Tube
This is a group of cells surrounding the oocyte, plays a role in the binding of sperm (it’s the epithelium it binds to)
Corona Radiata
Before sperm can bind to the corona radiata, the top layers of the _____ of sperm are taken away via the sperm attaching to the…
Epididymis of sperm
Attaches to the epithelium of the fallopian tube
During fertilization, after the sperm binds to the epithelium of the fallopian tube and sheds the epididymis, what effect does it have on the sperm?
The cell becomes highly motile, allowing it to bind to cells on the oocyte
What adhesion molecules play a role in capacitation?
E-Cadherins and integrins
This covers the sperm, and when it breaks down, it releases enzymes for breakdown of ____ allowing the sperm to fuse with enzymes of the egg
This whole process is called the
Acrosome Cap
Zonapellucida, ECM
Acrosome reaction
This part of the oocyte hydrolyzes sperm receptors, inactivating so no other sperm can penetrate once one already has
Cortical Granules
This is the word used to describe a cell that can differentiate into any cell or extraembryonic structure in our body
Totipotent
This is the term used to describe a cell that is capable of differentiating into several cell types, or any embryonic structure
Pluripotent
This is the period that begins with 24 hours after fertilization, the newly created diploid cell begins dividing
Cleavage
This forms 3-4 days after fertilization, it is a solid ball of cells
Morula
This forms 5-6 days after fertilization, it has an inner cell mass, tropho blast, and a cavity
Blastocyst
In the blastocyst, this is the outer ring of cells
It forms the _____ contribution to the placenta
Trophoblast
Embryonic
This is the innter cluster of cells that forms the embryo in the blastocyst
Embryoblast
Are cells totipotent or pluripotent in the embryoblast?
Pluripotent
This is the fluid filled space in the blastocyst that lies between trophoblast and embryoblast
Blastocyst Cavity
During week 1 of reproduction, the blastocyst implants into the functional layer of the ________
Endometrium
What adhesion molecules are important for binding of blastocyst to the uterine wall?
Integrins
Once the blastocyst is bound to the uterine wall, what divides to further penetrate into the endometrial tissue?
Trophoblast
During weeks 1-2, the trophoblast differentiates into 2 different layers..
Cytotrophoblast and syncytiotrophoblast
During weeks 1-2, this is the inner layer of the trophoblast in a developing embryo
Cytotrophoblast
During weeks 1-2 of reproduction, this is the epithelial covering of the highly vascular embryonic placental villi
Syncytiotriphoblast
During weeks 1-2, lakes of blood surround the ___________, allow it to continue to grow and fuse even furtehr into maternal embryonic tissues
Syncytiotrophoblast
This is the hormone secreted by the syncytiotrophoblast until the maternal tissues produce enough progesterone
HCG
During week 2, the embryoblast (bilaminar germ dis) starts epithelizing into…
Epiblast and Hypoblast
During week 2, epiblast cells differentiate to create the…
Note: Epiblast later becomes human tissues
Amniotic Cavity
During week two, the hypoblast also moves out like the epiblast, and line the cytotrophoblast to form the….
Yolk Sac
During week 2 (10-13 days), the hypoblast tissue continues to move out and create this connective tissue, between the hypoblast and cytotrophoblast
Mesoderm
During week 2 (10-13 days) this is generated from tiny spaces in the mesoderm
Chorionic Cavity
During 12-13 days, the yolk sac pinches off, becomes ______
The epiblast cells create the ________
The ______ surrounds everything, but there is a huge cavity
The amniotic cavity starts to become _______
Secondary Yolk sac
Amniotic Membrane
Extraembryonic mesoderm, (connective tissue)
Human tissues
So in sum of second week…..
During week three, the most important event in your life occurs
Gastrulation
What appears during the third week?
On what end of the embryo do cells cluster within the amniotic cavity to form it?
Primitive streak
Caudal
Why is the primitive streak important for gastrulation?
It establishes axes (caudal/cranial) (left and right) (anterior and posterior
To form the primitive streak, what type of cells migrate at the midline?
Epiblast
After establishment of the primitive streak within the amniotic cavity, which is ventral, the amniotic cavity or the yolk sac?
Yolk sac is ventral, amniotic cavity is dorsal
When epiblast cells migrate to the primitive streak, the cell detach, invaginate and replace the _______ to form the ________
Further migrating cells differentiate and form the
Hypoblast to form the endoderm
Mesoderm
When epiblast cells migrate to the primitive streak, what occurs
Why?
Epithelio-mesenchyme transition
Mesenchyme can move, lots of fluid allowing it to
During the epithelio-mesenchymal transition, the remaining epiblast cells that didn’t migrate to form the
Ectoderm
Once the 3 germ layers are formed during gastrulation, the cells are no longer….
But they are..
Pluripotent
Multipotent
At this point in the picture, what happens to the cells on top of the epiblast?
At this point in the picture, what happens to the cells that remain of the epiblast?
Cells on top detach, migrate, and form the mesenchyme
The remaining cells form the ectoderm
The yellow that is directly under the mesoderm in the picture is from what? Is it from the hypoblast
So then where is the hypoblast?
No, it’s from the cells that migrated through the primitive streak
It’s the part that doesn’t directly underlie the mesoderm
What does the migrating mesoderm (the red in the picture) become?
Connective Tissue
The black boundary in the middle is also formed from migrating mesoderm, what structure does it form?
The notochord
In the picture, the mesoderm that migrates along either side of the notochord is called the…
Paraxial Mesoderm
In the picture below, what are I and S? Also note the location of the lateral plate mesoderm
Also, what is the space above the blue line?
- I is the lateral plate mesoderm
- S is the paraxial mesoderm
- The space is the amniotic cavity
What is the blue and the yellow in the picture below?
- Blue is ectoderm
- Yellow is endoderm
What does the intermediate mesoderm form most of?
The urinary and reproductive system
What is the name for the space that exists because of the split in the lateral plate mesoderm?
Intraembryonic Coelom
What is the function/purpose of the space between the blue (ectoderm) and the outer intermediate mesoderm?
Supports the body wall with muscle and connective tissue
What does the space between the mesoderms, formed by the lateral plate (the intraembryonic coelom) become?
Abdominal Cavity
What does the space between the endoderm (yellow) become?
Gut Tube
This is the term describing the part of the mesoderm that becomes the body wall
Somatopleure
This is the term for the mesoderm that lines the outer part of the gut tube
Splanchopleure
As seen in the picture below, the mesoderm folds back over the ectoderm and endoderm. What is the mesoderm on top of the structure in the picture?
What is the mesoderm on bottom of the picture?
Somatopleure
Splachnopleure
Identify the colored areas in this picture
Which contributes most to the development of the notchord, ectoderm, mesoderm, or endoderm?
Mesoderm
The notochord defines the ___ axis of the embryo
It induces the development of these two things
- Defines the primordial axis of embryo
- Induces the development of the neural plate
- Induces development of axial skeleton
What forms around the notochord?
What eventually happens to the notochord?
The vertebral column
It regresses and mostly disappears (except for intervertebral discs)
The notochord loses its epithelial connection and becomes attached to the..
It then loses it’s epithelial connections once more and what happens ?
Endoderm
Cells at the end compact and it becomes a rod (see picture)
The paraxial mesoderm forms the….
Somites
- These are the striated muscles of the body wall
- They divide into two parts
Myotomes
Epimere and hypomere
- During segmentation, what folds in and creates neural tube?
- What is within the neural tube (ventral to neural tube here)
- Ectoderm
- Notochord (ventral to NT here)
The somites divide into three parts, what are they?
- Scleratomes
- Myotome
- Dermatome
Which aspect of the somite becomes cartitlage, supportive tissues, vertebrae and ribs
Scleratomes
Which part of the somite forms muscles of body wall and limbs (trapezius, splenius, lats)
Myotomes
- The myotome divides into two parts, called…
- This is the dorsal part of the myotome
- This is the ventral part of the myotome
- Epimere and Hypomere
- Epimere
- Hypomere
This part of the myotome gives rise to the deep back muscles
Epimere
This part of the myotome forms the ventral muscles and superficial back
Hypomere
This part of the somite becomes the dermis
Dermatomes
Identify the lines in this picture
To form the dermis, the dermatomes join with what?
Somatopleure
Identify the lines in this picture
Scleretomes on either side grow towards one another, fuse, surround neural tube, form the…
Spinal Vertebrae
These divide in half, top and bottoms of different ones fuse with one another, creating ones
Why is this beneficial?
Somites
It allows muscles to span vertebrae, creating movement
Also creates space for spinal nerves to travel
During neuration, as shown in the picture, what structure is folding out?
What does it form?
Ectoderm
Neural plate
During neurulation, what forms due to the rising of the lateral plate? The cells get thicker on at basal end but thinner at apical end
Neural groove and neural fold
At this point in the picture, the ectoderm is well positioned to form the ___ but not the _____
- Skin
- Brain
- When the neural folds reach eachother, where does fusion begin?
- What does this fold and fusion eventually form?
- In the middle, the fuses away from middle in cranial and caudal direction
- Neural Tube
What does the neural tube form?
CNS and somatic efferent (motor) neurons
Within the neural fold, these detach, migrate and become other nervous system processes (afferent neurons, dorsal root ganglia, much of ANS and ganglia, glial cells, many cells in endocrine and other body systems)
Neural crest cells
