EMBRYOLOGY 1ST WEEK Flashcards
The study of the origin and development of an organism. Begins with the fertilization of an oocyte by a sperm creating a zygote. This begins the human developmental pathway
Embryology
Before Birth
Prenatal period
Prenatal period is how many weeks?
38 weeks from conception, 40 weeks gestational age
When all major organs formed?
Embryonic period, or called the embryogenesis or organogenesis
The Fetal Period
Remaining 30 weeks, organs grow larger and more complex
How are early development described?
In stages from Fertilization
Stage 1 is..
Fertilization
Embryonic stage ends at
stage 23 (day 56)
Differentiated
When the cell becomes more specialized and have differentiated into a mature cell type
Morphogenesis
Formation of shape during development. Cells can change how they adhere to one another, can change their shape, migrate to new locations.
Dysmorphogenesis
Abnormal development…may occur due to malformation or deformation.
Signaling is when
one group of cells influences the development of another group of cells near or far
Signaling in the Embryo
Signalling of a vast array of different proteins by different cells allows those cells to gain information about current or future tasks
Paracrine Signaling
Act by signaling transduction pathways directly or by blocking the activity of an inhibitor
What are the four groups of Paracrine signaling proteins?
Wnt
Hedgehog
Fibroblast Growth Factor (FGF)
Transforming Growth Factor (TGT-B)
The Paracrine signaling protein Wnt
They are proteins which are a version of the wingless gene because mutating the gene caused flies to develop without wings.
Failure of the Wnt signaling protein causes?
Result in limb, eye, genitourinary and bone development disorders. Can be inhibited by sFrps which stop the signaling.
The Hedgehogs proteins are similar to?
Works like a skeleton key and can open a lot of different doors. the cell effect depends on type dosage and deferential of the cell
The Hedgehog proteins was first identified and resulted in?
Identified in Drosophila in the early mutation of the embryo. Gives the embryo the hedgehog like appearance and results in embryo being shorter.
The three Hedgehogs in humans?
1) Sonic hedgehog homologue (SHH)-
2) Indian Hedgehog (IHH)-
3) Desert Hedgehog (DHH)-
Sonic Hedgehogs protein is involved in?
Involved in neural, bone, limb, and kidney development plus muscle and lung. Also involved in the special sense organs. Binds to a cell transmembrane called Patched.
How many FGF’s are there?
22 varieties. In embryological development they are involved in limb and neural dev, angiogenesis, very early patterning and induction of mesoderm development
FGF receptors are part of?
the signaling transduction process. Interference with these effects causes a number of developmental abnormalities.
TGF-B is described as?
Part of the super family of signaling and includes the bone morphogenetic proteins (BMPs). Was thought to be tumor related but later identified in other events during embryological dev
How many forms of TGF-B and types of BMP’s discovered?
3 TGF-B and 15 types of BMP’s
TGF-B ligands bind and change what?
Bind to a type II TGF-B receptor and recruits a type I receptor and ultimately change DNA transcription
Juxtacrine Signaling
Occurs btw adjacent cells or btw a cell and the extracellular matrix…the direct contact affects the neural system and the heart along with other developmental areas.
Notch Gene
Discovered in Drosophila, it is populations known to help maintain stem cell also development in specific cell clusters such as neurone, endothelial, cardiocyte and T cell development to name a few
Interruptions to signaling in any way, be it proliferation, migration…can cause
Congenital abnormalities
If thalidomide is taken during embryo stage (3-8 wks)
Can cause phocomelia which is the shortening of the limbs
