click below
click below
Normal Size Small Size show me how
Embryology
Question | Answer |
---|---|
From which embryonic tissues are skeletal tissues derived? | paraxial mesoderm: sclerotome cells form the vertebrae lateral mesoderm: appendicular skeleton neural crest ectoderm: neurocranium |
From which embryonic tissues are all skeletal muscles derived? | paraxial mesoderm |
What is the role of CBFA-1 gene in bone development? | specific transcription factor |
What is the role of Sox-9 gene in bone development? | specific transcription factor |
What does the notochord remain as? | nucleus pulposus of the intervertebral disk |
What is mesenchyme? | non-polarized, often mobile, loosely organized embryonic tissue type derived from epithelium |
What is the chorion and how is it related to the amnion? | Chorion is the trophoblast and extraemryonic mesoderm |
What is the difference between splanchnic and somatic mesoderm? | Splanchnic: layer of LPM (lateral plate mesoderm) that associates w/ the endoderm after the LPM is split into two layers by the formation of the intraembryonic coelom. Somatic mesoderm: LPM that associates w/ the ecotoderm |
When and where does cleavage occur? | Day 2 in the mid-inner oviduct |
What do angioblasts form? | Vascular system (i.e. blood vessels). Derived from mesoderm. |
What is the first epithelium established in the embryo? | Trophoblast |
What is a transgenic animal and how is it made? | x |
When, where, and how does implantation occur? | Days 5-12, intrauterine (in central portion of the uterus), occurs by a process of 1. attachment and decidual reaction 2. Penetration & Embedment of endometrium by syncytiotrophoblast 3. Lacunae formation (uteroplacental circulaiton) |
What are the major derivatives of the epiblast? | All of the cells that will form the embryo are w/in the epiblast. |
What are somites and how do they form? | aggregations of mesenchyme in the paraxial mesoderm that eventually segregate into scleretome (vertebrae precursor) and dermomyotome (dermatome/myotome) |
what is the primitive streak? | a transient mid-line thickening of the caudal epiblast due to a converging of cells |
What happens if the primitive streak does not disappear during development? | a teratoma forms usually in the sacrococcygeal region |
What are homeotic genes and what role do they play in development? | Such as the HOX and PAX genes control differential gene expression and patterning events such as the formation of body segments and positioning of structures |
What are differences between syncytiotrophoblast and cytotrophoblast? | syncytiotrophoblasts are multinucleated cell mass with no cell boundaries that secrete proteases to invade the edometrium. Cytotrophoblast has distinct cell boundaries and are polarized, it is the original trophoblast layer that retains epithelial nature. |
What is regulation? | The ability of an embryo to produce a normal embryo when parts have been removed or added. Regulation ability decreases with increasing age of the embryo. |
Where are embryonic stem cells (ES cells) derived from? | ES cells are derived from the inner cell mass (ICM) because they are pluripotent (i.e. have the potential to develop into any cell type in the adult) |
What is the decidual reaction? | The maternal recognition of pregnancy, provides mass of cells into which embryo can implant, thickening of endometrium, transformation of 1/3 of embryo into the compact layer. |
How does mesenchyme form? | epthelial/mesnchymal transformation: epethelial cells lose polarity, change shape, down regulate CAMs, and up regulate substrate adhesion moecules |
Splitting of the extraembryonic mesoderm results in the formation of what space? | chorionic cavity |
What are the chroionic villi called that become vascularized? | tertiary |
How long does the corpus luteum normally funtion, in the event of a pregnancy? | 4 months |
What is the most characteristic feature of the maternal surface of the placenta? | cotyledons |
During lateralization of the embryo Lefty-2 is thought to induce leftsided transformations. What is the suspected repressor for left sided development on the right side of the embryo? | SHH |