Embryology Flashcards
What is the name given to the parent gametes ?
spermatogonium and oogonium
What does the process of meiosis produce in males and females?
Males - 4 sperm
Females - 1 egg + 3 polar bodies (which degenerate)
Where does fertilisation occur?
The ovum
What is a morula ?
The zygote undergoes mitosis to form a solid ball of cells
What is a blastocyst?
The morula divides into two forming the trophoblast and an inner mass of cells. It also have an blastocyst cavity which nutrition can move into helping the cells to get nutrition.
What do the layers in the blastocyst go on to form?
Trophoblast - Placenta
Inner ball of cells - Baby
What is implantation ?
When the blastocysts buries itself in the endometrial lining. Controlled by the trophoblast which divides into two forming the chorion.
What hormone foes the chorion produce?
HCG (Human chorionic gonadotropins)
At what week does the placenta start supplying the baby with nutrients?
12
What is the name given for the endometrial lining once’s the blastocyte has implanted?
Decidua basalis
What is a bilaminar disc?
During implantation the inner call ball forms two layers which is called the bilaminar disc. This forms an upper cavity called the amniotic cavity and a lower cavity called the yolk sac.
What are the two layer in the bilaminar disc called?
Epiblast and hypoblast
What is a primitive streak?
The groove that is created which runs down the top of the bilaminar disc. (Epiblast)
What are the three layers that are formed during gastrulation?
Ectoderm
Mesoderm
Endoderm
Describe gastrulation
Cells from the epiblast migrate to lie between the epiblast and hypoblast forming the mesoderm.
Describe neurulation
Cells of the ectoderm descend down and form a ball of cells which disconnects under the mesoderm and is called the notochord.
The primate chord thickens and forms a neural tube under the surface of the ectoderm.
What happens after neurulation?
Mesoderm thickens and forms a paraxial mesoderm intermediate plate mesoderm and lateral plate mesoderm.
What happens to the paraxial mesoderm ?
It divides into 3- the dermatome (Skin), myotome (muscles) and sclerotome (bones)
Describe the folding that then takes place in the embryo?
The three layers fold round each other to create a tube.
What layer will form the respiratory system?
The endoderm
What is teratology ?
The study of things that go wrong in development
Describe how the endoderm forms the respiratory system
Endoderm gives rise to the privative gut tube which has a hindgut, midgut and foregut. The trachea and lung buds form from the ventral wall of primitive foregut.
How does the pleura form?
As the lung bud forms it pushes the splanchnic mesoderm towards the somatic mesoderm so that the lung bus is surrounded by both layers.
Name the stages in the development of the respiratory system ?
Embryonic Pseudoglandual Canalicular Saccular Alveolar
What happens in the Pseudoglandual phase (Respiratory)?
7-17 weeks
development of all lung structures except respiratory part
What happens in the Canalicular phase (Respiratory)?
17-27 weeks
There is the formation of the respiratory part. Alveolar ducts form and epithelium starts to differentiate into Type 1 and type II pneumocytes
What happens in the saccular phase (Respiratory)?
27 weeks - 40 weeks
Formation of the alveolar sacs, primitive alveoli and surfactant. Gas exchange begins.
What happens in the alveolar phase (Respiratory)?
32 weeks - 8 years
proliferation of alveoli form alveolar sacs. 95% of adult alveoli are formed postnatally.
From what does the diagram develop?
Mesoderm
The diagram develops from 4 mesodermal structures, they are …
Septum transversum - forms the central tendon
Pleuroperitoneal folds - grown in from peripheries and fuse with septum
Skeletal muscle - Cover the pleuroperitoneal folds and forms the muscular part
Doral mesentery of the oesophagus - Forms the crura
Name a few congenital lung conditions
- TOF or oesophageal atresia. The oesophagus has not correctly disconnected from the trachea.
- IRDS - Lack of surfactant
- Lung agenesis. Failure of lung development.
- Diagram isn’t completes closed (hernias) and hypoplasia (lack of growth).
