2: Fertilisation to trilaminar embryology Flashcards
What is the zona pellucida?
A thick membrane surrounding the oocyte before implantation of sperm
Where is the ampulla?
Uterine tube
What is the site of fertilisation?
Ampulla
In the first part of fertilisation, a sperm cell binds to the ___ ___ of an egg cell.
zona pellucida
The sperm cell breaks down the zona pellucida using ___.
enzymes
Which granules prevent polyspermy following fertilisation of an egg cell?
Cortical granules
Cortical granules cause a change in the structure of the ___ ___ which prevents entry by more than one sperm cell.
zona pellucida
What daughter cells are formed by a dividing zygote during cleavage?
Blastomeres
Up to the 8 cell stage, blastomeres are thought to be totipotent.
What does this mean?
They can go on to differentiate into any other type of cell
What confines cells during the beginning of embryological development?
Zona pellucida
Blastomeres
Morula
Zygote
Blastocyst
Arrange in chronological order.
Zygote
Blastomeres
Morula
Blastocyst
After the first week, the blastocyst ___ from the zona pellucida.
hatches
Once the embryo has hatched from the zona pellucida, what can it interact with?
Endometrial lining of the uterus
What is the trophoblast?
Placental part of the embryo
By which process does the embryo attach to the uterine wall?
Implantation
What part of the embryo drives implantation?
Trophoblast
What is cytotrophoblast?
Trophoblast made up of individual cells
What is syncytiotrophoblast?
Trophoblast made up of one single, multinucleated cell
During implantation, the embryo organises into two layers - what are they called?
Epiblast
Hypoblast
At the point of implantation, the embryo is a (bilaminar / trilaminar) disc.
bilaminar
When the embryo is a bilaminar disc, what cavity is found within the epiblast?
Amniotic cavity
When the embryo is a bilaminar disc, what is found within the hypoblast layer?
Yolk sac
At Day 14-15, the ___ has made contact with the maternal blood supply.
syncytiotrophoblast
What happens to the number of germ layers during gastrulation?
Two germ layers become three
What appears at the caudal aspect of the embryo at the end of Week 2?
Primitive streak
The primitive streak appears at the (cranial / caudal) end of the embryo.
caudal
What happens at the primitive streak during gastrulation?
Cell migration
The primitive streak appears in the (epiblast / hypoblast) of the embryo.
epiblast
During gastrulation, the number and names of the germ layers change.
Describe the change.
Before gastulation:
Epiblast
Hypoblast
After gastrulation:
Ectoderm
Mesoderm
Endoderm
In gastrulation, what replaces the epiblast?
Ectoderm
In gastrulation, what replaces the hypoblast?
Endoderm
In gastrulation, what germ layer appears between the new ectoderm and endoderm?
Mesoderm
What structures does the ectoderm go on to become?
Epidermis (skin, hair, nails, glands)
Nervous system
What structures does the paraxial mesoderm go on to become?
Axial skeleton
Skeletal muscle
What structures does the intermediate mesoderm go on to become?
Urogenital system
What structures does the lateral visceral mesoderm go on to become?
Cardiovascular system
Organ coverings
Smooth muscle
What structures does the lateral somatic mesoderm go on to become?
Lining of body wall
Dermis
Limbs
