Flashcards in Embryology Deck (71):
What are the 3 main phases in human development?
During oogenesis, an ova is produced alongside what?
3 polar bodies
What part of the sperm enters the ova during fertilisation?
What is the morula?
A solid ball of cells
What does the morula become?
What is the name given to the accumulation of cells within a blastocyst?
The inner cell mass
What is the name of the outer lining of cells within the blastocyst?
From the 1st cell division to the following cell divisions, what happens to the time taken for these cell division to occur?
The time decreases
What is the uterine tube lined with?
When does an eptopic pregnancy occur?
When the zygote cannot move through the uterine tube
Implantation takes place in what week of the pre-embryonic phase?
Where does the blastocyst burrow down into during implantation?
The uterine wall (endometrium)
What does the trophoblast then form during week 2 of the pre-embryonic phase?
What are the finger-like processes devloped by the chorion?
What secretes HCG?
What does HCG indicate?
That a pregnancy is occurring
Where is the fetus nurtured?
When do maternal blood levels of HCG stop increasing?
What happens to allow the epiblast and hypoblast to form?
The inner cell mass flattens
What 2 layers make up the bilaminar disc?
What is the name of the cavity above the epiblast?
The amniotic cavity
What is the name of the cavity below the hypoblast?
The yolk sac
What is the purpose of the amniotic cavity?
To protect the embryo
What separates the maternal blood vessels from the foetal blood vessels?
What are the 3 main functions of the placenta?
Transport of waste and gases
What forms the placenta?
The chorionic villi
In fraternal births, how many ova are released?
What is the name given to the dip in the epiblast?
The primitive streak
What is the name of the 3 layers formed during gastrulation?
What is the collective name given to the the ectoderm, the mesoderm and the endoderm?
The trilaminar disc
What is the name given to neural tube formation?
Where does the notochord sit?
In the mesoderm
What induces the ectodermal cells in the midline to form a neural line?
What does the newly formed neural tube induce the mesoderm to do?
What 3 parts do the mesoderm split into on either side?
Lateral plate mesoderm
Which mesoderm splits into the somatic and splanchnic mesoderms?
Lateral plate mesoderm
What does the paraxial mesoderm form?
Which mesoderm forms the urogenital system?
The intermediate plate mesoderm
How many blocks form to become somites on either side of the neural tube?
Why does the embryo start to fold laterally?
Due to the mesoderm becoming so heavy
What is the foetal position of the embryo due to?
The head and tail fold of the zygote
What 3 things does each somite divide into?
Where is the nucleus palposus of the IV discs formed from?
What is teratology?
The study of when things go wrong during development
During which weeks is there the greatest sensitivity to teratogens?
How do infectious agents affect the developing embryo?
Transfer through the placenta
In which week does folding of the embryo take place?
What is the origin of the formation of the gut tube?
What does longitudinal folding of the embryo give rise to?
Foregut and hindgut
At what week gestation do the lungs develop?
4 weeks gestation
At what week of development do the nasal pits deepen?
What does the respiratory primordium start out as?
A median outgrowth
What does the larynx develop from?
Where does the cartilage of the larynx develop from?
The 4th-6th pairs of pharyngeal arches
Where does the epiglottis develop from?
The caudal part of the hypopharyngeal eminence
What is caused as a result of recanalization failure?
What does laryngeal atresia cause the lower airways to do?
How can laryngeal atresia be detected?
What gives rise to the laryngotracheal diverticulum?
The laryngotracheal groove
Lung bud formation is a result of what?
Ventral outgrowth of the foregut endoderm
When does a trachea-oesophageal fistula occur?
When there is incomplete separation of the trachea and oesophagus
Why won't a foetus survive if born during the pseudo-glandular stage of development?
As the major gas exchange elements have not formed
During the canalicular stage, what happens to the lumina of the bronchi and terminal bronchioles?
During what week of embryonic development, do the terminal sacs become lined with type 1 and 2 pneumocytes?
Which type of pneumocytes secrete surfactant?
What is surfactant a mixture of?
Phospholipids and proteins
What does surfactant prevent the collapse of?
Alveoli sacs during exhalation
What is the major cause of respiratory distress syndrome?
What happens to the number of alveoli at 8 years old?
They reach the adult number of alveoli
What are the 4 embryonic components that form the diaphragm?
Dorsal mesentry of oesophagus
Muscular ingrowth from lateral body walls