Exam 1 Flashcards
What two periods make up the first trimester?
Preimplantation period and embryonic period
____ and _____ molecules act through signaling complexes which activates _____ factors, affecting ____ changes
Growth factors
Cell adhesion
Transcription
Cellular
The cellular changes induced by growth factors and cell adhesion molecules can cause what kinds of cellular changes?
Proliferation
Differentiation
Apoptosis
Name some things that the growth factor BMP is responsible for
Craniofacial development
At gastrulation, it switches between epidermal vs. neural fate
Patterning and formation of facial primordia
Control of neural crest cells**
Regulator of early tooth morphogenesis and differentiation
What types of genes code for transcription factors that make cells pattern into one tissue/organ type or another? These genes are also involved in bodily segmentation during embryonic development.
Homeobox genes
True or false… cell adhesion molecules are responsible for specific cell aggregation and sorting and involves cell-cell contact.
True
in regards to cell adhesion molecules… Cadherins are calcium ____ whereas CAMs are calcium _____
Dependent
Independent
Neuroectoderm progenitors express ____ while skin ectoderm progenitors express ____
N CAM
L CAM
What period takes place during the first week after conception? Describe what occurs in this period.
Preimplantation period
An oocyte (arrested in metaphase 2) is penetrated by sperm to form a diploid zygote. The zygote undergoes cleavage to form a solid morula (day4), then a vesicle called a blastocyst.
True or false… if nondisjunction occurs in meiosis 1, it is possible to produce normal haploid gametes.
False. None of the gametes will be normal as half will be N + 1 while the other half will be N - 1.
If, however, nondisjunction occurs in meiosis 2, you will get half normal gametes, one N + 1, and one N - 1.
Describe the difference between the trophoblast and embryblast.
In a blastocyst, the outer portion of cells are called the trophoblast. The internal fluid pushes the inner cell mass to one side, this is called the embryoblast.
True or false… no differentiation occurs during cleavage
True
True or false… the morula is what implants into the endometrium
False.. it is the blastocyst that implants into the endometrium
The trophoblast will give rise to the ___
Placenta
Describe where you would find the primary yolk sac in a blastocyst
It is the ‘internal fluid’ of the blastocyst. It is between the embryoblast and the trophoblast
Which is important for implantation, the trophoblast or the embryoblast?
The trophoblast. This is what invades the endometrium
Name some basic patterning events that occur during the embryonic phase?
Axial specification (which end is up)
Segmentation
Tissue and organ specialization and formation
Define induction
When one group of cells tells another group of cells, which are said to be competent, to do something
Define proliferation
Cell division. Increase in number and accumulation
Define differentiation
Development of specific structures and or functions by individual cells or groups of cells
Define morphogenesis
Cell migration, interactions and proliferations, causing the development of groups of cells
Define maturation
Attainment of adult size and function from proliferation, differentiation, and morphogenesis
After the blastocyst implants, the embryoblast differentiates into what two layers? What will these layers give rise to? What types of cells make up each of these layers?
Epiblast (dorsal cells), (high columnar): these will give rise to amniotic cavity and the three germ layers
Hypoblast (ventral cells), (small cuboidal): form the roof of the secondary yolk sac and some of the endoderm
True or false… the openings (mouth and anus) have direct contact between ectoderm and endoderm
True
After formation of the bilaminar disk, a structure called the ____ is formed which defines the future bilateral symmetry along the rostral-caudal axis.
Primitive streak
The ____ forms at the rostral end where the ectoderm curve around to integrate with the endoderm. This will give rise to the mouth
Prochordal plate
Describe how mesoderm is formed
Induced epiblast cells will essentially fall into the primitive streak and migrate outwards in between the epiblast and hypoblast layers
During gastrulation, ectodermal cells invaginate at the ___, forming the ____
Primitive node
Primitive pit
Other than the formation of the three germ layers, what other important structure is formed during gastrulation?
The notochord
True or false… the induced epiblast cells that fall into the primitive pit are called mesoblast cells. These cells will give rise to both mesoderm and endoderm
True
The cecal plate will give rise to the ____
Anus
The stomodeum (also known as the ____), is covered with the ______
Primitive mouth
Oropharyngeal membrane
True or false… the epithelium lining the oral cavity is derived from endodermal cells
False… it is derived from ectodermal cells
True or false… both enamel and dentin are derived from ectodermal cells
False… the enamel is derived from ectodermal cells whereas the dentin is derived from neural crest cells
In the oral cavity, the neural crest cells will give rise to the ___, ___, ____, and ____
Dentin
Pulp
Cementum
PDL
After week three (post gastrulation), what three key events take place?
Differentiation of the nervous system
Formation/migration of the neural crest
Embryo folding
What are the three main folds in embryo folding?
Lateral folds, head fold, tail fold
The onset of folding occurs at day ___
24
The neuroectoderm, a specialized group of cells that differentiates from the regular ectoderm, extends from the cephalic end to caudal end. The plate undergoes further growth and thickening which causes it to deepen and invaginate inward to form the ____. When this invagination closes in on itself, it is called the ____
Neural groove
Neural tube
If you replace BMP and Wnt with FGF. ____ will be induced to become ____
Ectoderm
Neuroectoderm
Describe neural tube closure
The neural fold fusion begins at upper cervical levels, then closes in both directions rostrally and causally
A defect in the neural tube closure can result in ____
Spina bifida
The differentiated ____ gives rise to somites on either sides of the developing nervous system. The somites are further differentiated into three sections. Name these sections and what each one gives rise to
Mesoderm
Paraxial - cartilage, segmented muscle
Intermediate - kidneys, gonads
Lateral plate - heart, gut
The neural tube expands to form the forebrain, midbrain, and hindbrain. The hindbrain segments into ____ which express ___ genes
Rhombomeres
Hox
The branchial arches develop in the head region too
The neural ectoderm develops from the ___ during the ___ week
Neuroectoderm
Third
True or false… the head fold is critical to the formation of the oral cavity
True
Bone is _____ formed on a ____ matrix with various _____ proteins
Hydroxyapatite
Collagenous
Non-collagenous
Describe the difference between endochondral and intramembranous ossification. What kind of bones do each process form?
Endochondral - bone that is formed on a cartilage template (long bones).
Intramembranous - bone that is formed from condensation of mesenchyme (most of the mandible, skull plates)
What is mesenchyme?
Cells floating around in ECM that can form CT
True or false… other than serving as a template for endochondral ossification, cartilage can also drive the formation of bone by intramembranous ossification through signaling
True
Define initiation
Start of ossification, whether conversion of cartilage to bone or condensation of mesenchyme/neural crest to bone
Define growth in regards to bone
Addition of more bony matrix to a pre-existing bone; thickening/elongation.
Depends on the rate of resorption and bone deposition
Describe the difference between primary displacement and secondary displacement
Primary - movement of a bone due to its own growth (finger goes further out because of lengthening of finger bone)
Secondary - movement of a bone due to the growth of surrounding bones (finger goes further out because of growth of arm)
Define remodeling in regards to bone
Growth involving simultaneous deposition and resorption on all peri-endosteal surfaces; changes size, shape, proportion, relationship with adjacent structures
Involved in healing. For example, when you fracture a bone, it is immediately filled with weak collagen 3. Then it is displaced by collagen 1 by the action of osteoblasts and osteoclasts
Define drift in regards to bone
Remodeling that results in movement of a bone towards the deposition surface