Embryology Flashcards
If something goes wrong with the development of an embryo, what may happen?
The child may be born anatomically different to other children.
If abnormalities occur at a very early stage, this is usually ………… and will not result in a ……….. ……..
fatal
live birth
Between which stages does embryology not occur?
Fertilisation and implantation
After fertilisation, the ovum divides many times to produce smaller cells. What is this bundle of cells called?
Morula
What is the Morula attached to?
Nothing, it is floating freely in the uterus, therefore is getting no nutrition.
The morula cannot grow but it can develop. What does it develop into?
It develops into a blastocyst.
Around what day can a blastocyst be seen?
day 5-7
What is a blastocyst, and what is inside?
It is a sphere of cells, containing an inner cell mass (a collection of cells at one side of the ring) and a space in the middle.
Another space (amniotic cavity) forms within the inner cell mass. What does the inner cell mass become?
It becomes the embryo.
What is a trophoblast?
It is the outer layer of cells on the blastocyst that later form the placenta.
To form the placenta, the trophoblast grows into the ……….
Uterus
What is the ectoderm?
The most exterior of the three primary germ layers formed in the early embryo.
Another layer of cells forms around the space in the blastocyst. What is it called?
The endoderm.
As we develop, an …………. ………. is formed between the cell mass (embryo) and the placenta.
extracellular matrix
The cells of the extracellular matrix secrete chemicals, causing them to break down into ……….. between the endoderm and ………….
holes
placenta
What is the developing placenta called?
Cytotrophoblast
What 8 things will the ectoderm develop into?
Epidermis of skin, hair and nails Mammary, sweat and sebaceous glands Central nervous system Peripheral nervous system Enamel of teeth Lens of eye and parts of inner ear Sensory epithelium of nose, ears and eyes
At what stage is the earliest that we start to call the cells an embryo?
When the bilaminar disk is formed.
What is the conceptus?
The fertilised tissue.
Which is the only bit of the conceptus which will develop into the live birth?
The bilaminar disk (embryo).
What is the primitive streak?
A groove on top of the ectoderm that appears as the embryo develops.
What happens to cells from the base of the primitive streak?
They break off and migrate to lie in the space between the ectoderm and endoderm, creating the mesoderm.
What does the mesoderm develop into?
Whole musculoskeletal system Deep layers of skin Abdominal and chest walls and lining Walls of bowel (not lining) Urogenital system
By day …….. there is a trilaminar disk.
17
In which two places does the mesoderm not separate the ecto and endoderm?
The head end of the embryo and an area at the back of the other end of the embryo.