Human Embryo And Stem Cells Flashcards
Stages of embryo development (recall the image of female tract and what stages they are when they go)
Ovulation then leads to fertilisation in fallopian tube and reaches many stages through fallopian till embedded into uterus lining names of stages:
zygote, 2 cell stage, 4 cell stage, 8 cell stage, morula, compacted morula, early blastocyst, late blastocyst.
What is embryo grading?
Embryo and blastocysts graded to UK system NEQAS, they govern all quality of biomed through the UK in all labs
Describe a blastocysts structure
ICM inner cell mass forms the fetus
Trophectoderm forms extra embryonic tissues
Fluid filled cavity called blastocoel cavity
Outer ZP layer broken via proteases before implantation (hatched)
Three stages of implantation and where does it occur plus time period
Implantation occurs in endometrium between day 20-23
Three phases:
1.Apposition
2.Adhesion via Osteopontin secreted by endometrial glands
3.Invasion
What are stem cells?
Cells that can crate more stem cells or specialised cells
Embryonic stem cells
Adult tissue stem cells
What is ICM (inner cell mass)
Pluripotent stem Cells which form humans (day 5-9 after fertilisation)
Can be collected and cultured
Three types of cell potency and what they do
Totiponent: generate all types of body,germ and cells of placenta, few divisions only
Pluripotent: generate all type of body cells (cells of the inner cell mass
Multipotent: generate limited cell types, tissue progenitors
What are Adult stem cells aka tissue stem cells
Partially differentiated
Limited potential for differentiation- multipotent
Types of adult stem cells
Bone marrow
Peripheral blood
Skin
skeletal muscle
Liver brain heart
Adipose tissue
What is Tissue renewal
Tissue renewal determines rate of cell division
In many tissues renewal derives from limited number of stem cells
Eg spermatogenesis
What are the three germ layers?
Ectoderm mesoderm and endoderm for each type of tissues
These three are derived from photophores embryonic stem cells from the ICM in blastocyst
What are the three developmental periods called?
Germinal (germ layers), embryonic (3-8 weeks), and fetal (9 weeks to birth)
Carnegie stages show development of embryo
Germinal period notes
Shortest developmental stage from zygote to implanted embryo
Week 1: from zygote to implanted blastocyst
Embryonic period
From implanted blastocyst to fetus growth occurs via cell division
Morphogenesis: development of shape size of particular organ or body
Differentiation: maturation of physiological process like placenta
Week 3: gastrulation occurs where germ 3 layered cells form embryo/gastrula
Fetal period
8-38 week of development and has human limbs due to morphogenesis
Maturation phase
Abortions occur before 24th week unless medical reasons
9-12th week pregnancy earliest movements recorded
Impact of age on pharmacology
Germinal phase: high rate of lethality
Embryonic phase: period of greatest sensitivity each organ has peak sensitivity period of its own (most impact to lead to defects)
Fetal phase: decreasing sensitivity due to period of maturation
What is situs in versus?
Inverted organs so left side organs are all at right side of body vice versa
