Early Embryonic Development and Cell Types Flashcards
Describe the structure and embryonic origin of the umbilical cord
Umbilical Cord formed in area of dotted line on left-hand diagram
The Vitello-intestinal duct is the area connecting the gut tube to the remnants of the yolk sac
Describe the 3D shape of the horseshoe intraembryonic coelom as the embryo develops
The 3D shape changes so the horseshoe is bent
Divisions occur to allow the pericardial cavity to form; then eventually on either side to allow the formation of the pleural cavities and peritoneal cavities
Connection between intra- and extra- embryonic coeloms shrinks and gets smaller to eventually separate
*** Note that picture is ‘upside down’
What is housed in the peritoneal cavity
Gut Tube, Liver, other organs (except heart and lungs)
What happens to the ectoderm that surrounds the embryo and the mesoderm directly below it in an adult
Becomes the skin;
Mesoderm becomes the dermis
How do the peri-cardio and peritonial canals look from a cross section of an embryo (just see the picture)
What does a transverse cross section of the almost pinched off yolk sac look like
Hands could theoretically meet across peritoneal cavity
What are derivatives of the Ectoderm
**Neuroectoderm and External Epithelia
What are derivatives of the Mesoderm
**Paraxial are the somites
What are derivatives of the Endoderm
**Internal Epithelia
How do embryos develop
**Be vaguely aware of this, don’t fuss over details
Two main characteristics of stem cells
Unspecialised and can divide repeatedly over long periods
Can be induced to differentiate into cells with special function
How to isolate embryonic stem cells
Isolating the inner cell mass of a cultured blastocyst and putting them into special culture conditions where they divide by mitosis and undergo treatment with specific factors to specialise
What are the pathways where mitosis and differentiation occur relative to each other by stem cells
- They continuously divide into more stem cells
(e. g. blastocyst formation) - They divide into stem cells then differentiate into the same cell type
(e. g. haematopoeisis) - They divide then one daughter specialises and the other remains a stem cell
(e. g. skin/basal cells)
Why can even the least differentiated adult stem cells not be used to make all cell types
They differentiate as desired in-vitro but are not stable to behave in such ways when implanted into the body
Totipotent
Stem cells that can give rise to all cell types found in the adult organism, as well as extraembryonic cells
e.g. Zygote