Embryology Flashcards
What will ectoderm differentiate into ?
Nervous system
Epidermis
What will mesoderm differentiate into?
Supporting tissues:
Muscles, cartilage, bone, vascular system (heart & vessels)
What will endoderm differentiate into?
Internal structures:
Epithelial lining of GI tract, respiratory tract, parenchyma of glands
What are the 2 types of folding ?
Cephalocaudal folding (Head-to-head)
Lateral folding (side-to-side)
What does folding achieve ?
-Draws together margins of disc and created ventral body wall putting amniotic membrane around the disc, so embryo becomes suspended in amniotic sac
-Pulls connecting stalk ventrally (becomes umbilical cord)
-Creates primordium of gut
What are the 5 stages of embryology ?
- Fertilisation
- Implantation
- Gastrulation
- Neurulation
- Folding
Difference between to totipotent and pluripotent cells
(BEFORE compaction)
Totipotent: Able to differentiate into any cell type
(AFTER compaction)
Pluripotent: Able to differentiate into one of many cell types
Explain what happens in the pre-embryonic stage
- Cleavage
Initial mitosis split of the zygote resulting in the formation of 2 blastomeres. - Compaction
Formation of the cavity resulting in the formation of a blastocyst where there is the inner cell mass (embryoblast) and outer cell mass (trophoblast)
Summarise Gastrulation
When: 3’rd week (embryonic period)
What: Formation of trilaminar embryonic disc from bilaminar disc
How: Primitive streak on the surface of epiblast layer forms in the caudal epiblast, leading to migration & invagination of epiblast cells
Why: To ensure the correct placement/precursor tissues to allow subsequent morphogenetic to take place
Describe what happens during placenta praevia
Implantation in the lower uterine segment
Can cause haemorrhage in pregnancy
Required C-section delivery
Describe what happens during an ectopic pregnancy and why is this a medical emergency ?
Implantation at the site other than uterine body (mostly Fallopian tube)
Can be peritoneal/ovarian
The Fallopian use doesn’t have the ability to expand which can result in rupture of Fallopian tube and haemorrhage
What will trophoblast become ?
- Syncytiotrophoblast (multi uncleared sheet used fro transport)
- Cytotrophoblast (single called layer forming stem cells layer)
What will embryoblast become
Bilaminar disk
1. Epiblast (produces each of the germ layers of the trilaminar disc)
2.Hypoblast (becomes yolk sac)
Summarise neurulation
Notochord send signals to overlying ectoderm
Overlying ectoderm thickens and curves upwards
Forms neural tube
What are the 3 somite derivatives ?
Dermatology
Myotome
Sclerotome
