Early Embryonic Development And Cell Types

Question 1

Pericardial cavity houses the?

Answer 1

Heart

Question 2

Pleural cavity houses the?

Answer 2

Lungs

Question 3

Peritoneal cavity houses the?

Answer 3

Gut tube

Question 4

Embryonic differentiation

Answer 4

Embryonic cells specialise and diverse tissue structures arise, each with specific functions in the body;
In very early embryonic development - embryo does not possess these varied cells;
Differentiation is key to cell, tissue,organ and organism identity;

Question 5

Embryonic differentiation process

Answer 5

Zygotene divides into muscle isle cells (cleave);
Produces blastomeres;
Which form the blastocyst;
Cells migrate within blastocyst to locations that will later define the embryo and consequent organism;
Gastrulation - 3 germ layers are formed - endoderm, ectoderm, mesoderm;

Question 6

Ectoderm forms the..

Answer 6

Surface of the body - skin, hair, nails, mammary glands;

Neuroectoderm - CNS, adrenal medulla;

Question 7

Endoderm forms the…

Answer 7

Epithelia of internal surfaces -
Alimentary system;
Urinary system;
Respiratory system;

Question 8

Mesoderm forms the…

Answer 8

Lateral mesoderm - connective tissue, muscle;
Intermediate mesoderm - urinogenital system;
Head mesoderm - skull, connective tissue;
Paraxial mesoderm - skeleton, dermis, connective tissue;

Question 9

Initially the embryonic stem cells are…

Answer 9

Pleuripotent

Question 10

Transcription factors

Answer 10

Cells have an inherent ability to control what genes are expressed and translated into proteins;

Different signals can cause embryonic stem cells to select specific parts of DNA which can then be used to synthesize proteins, eventually building different cell types (division of labour)

Question 11

Differentiation is brought about by…

Answer 11

Both internal cellular factors and extracellular factors

Question 12

Regulation development

Answer 12

Involves interaction of adjacent cells with ‘embryonic fields’ - gives flexibility to differentiation;

Question 13

Varied relations between mitosis and differentiation

Answer 13

M without diff;
M with diff into identical Daughter types;
M with divergent diff into different Daughter types;
M with divergent diff into a differentiated Daughter cell and a retained stem cell;

Question 14

M without differentiation

Answer 14

Early zygote cleavages

Question 15

M with differentiation into identical Daughter types

Answer 15

Hepatocyte division;

Question 16

M with divergent differentiation into different Daughter types

Answer 16

Multipotent stem cells of blood forming tissues;

Question 17

M with divergent differentiation into a differentiated Daughter cell and a retained stem cell

Answer 17

Epidermis

Question 18

Stem cell generate…

Answer 18

All the differentiated cells needed for development and proper functioning;

Question 19

2 important characteristics of stem cells

Answer 19

Unspecialised and can divide repeatedly over Long periods;

Under certain conditions, they can be induced to differentiate into cells with special functions;

Question 20

Types of stem cells

Answer 20

Totipotent - all cell types and extraembryonic cells (zygote)
Pluripotent - can give rise to all 3 germ layers but not extraembryonic (cells of inner cell mass of blastocyst - where embryonic stem cells are derived);
Multipotent - can give rise to restricted number of different cell types (stem cells of blood forms tissues and adult stem cells)

Question 21

Embryonic ste cells and adult stem cells are used in…

Answer 21

Biomedical research (cell therapy)

Question 22

Adult stem cells

Answer 22

Valuable in treating diseases;
Multipotent - restricted ability to form different cell types;
Diasadvantages - slow rates of division, scarcity;

Question 23

Mature (adult) stem cells may replace tissue damaged by disease or injury

Answer 23

Replace neurons damaged by spinal cord injury, stroke, Alzheimer’s, Parkinson’s etc
Produce insulin - treat diabetes, heart muscle cells (after heart Attack);
Replace virtually any tissue or organ diseased or injured;

Question 24

Embryonic stem cells (EC)

Answer 24

Derived from inner cell mass;
Pleuripotent - can form any true type;
Potential for curing variety of diseases - diabetes, Alzheimer’s, Parkinson’s, anaemia, spinal cord injured;
Obtained from embryo after IVF (reproductive cloning);
May cause immune rejection;
Ethical considerations;

Question 25

Therapeutic cloning/ somatic nuclear transfer

Answer 25

Nuclei from adult cell introduced into ennucleated oocytes; Oocytes stimulated to differentiate into blastocyst and cells harvested; Genetically compatible; less controversial as no fertilisation involved

Question 26

ES therapy can do such more than adult

Answer 26

Studying how stem cells develop into heart muscle cells could provide clues about how we could induce the heart to repair itself after heart Attack; Used to study disease, identify new drugs, screen drugs for toxic side effects;

Question 27

Abnormal zygotes

Answer 27

Exact number formed is unknown; Lost within 2-3 weeks of fert; 50% pregnancies end in spontaneous abortion - half due to chromosome abnormalities; Abortion - actual means of screening embryos for defects - reduce incidence of congenital malformations; With the combination of IVF and PCR - molecular screening of embryos for genetic defects is being conducted