TBL 5B General Embryology Flashcards
Fertilisation usually occurs at the _____ of the uterine tube.
ampulla (Widest part of the fallopian tube)
The lateral end of the Fallopian tube has finger-like projections known as _____. These projections help to bring the oocyte into the fallopian tube.
fimbria
If the oocyte is not fertilised in the ampulla, it will pass along the fallopian tube into the _______, where it degenerates.
uterine cavity
The plasma membrane of the oocyte is surrounded by a glycoprotein coat known as ___________.
zona pellucida
The glycoprotein coat surrounding the plasma membrane of the oocyte, known as zona pellucia, is in turn surrounded by layers of follicular cells known as ________.
corona radiata
Fertilisation occurs in 3 phases. Rearrange the following.
A) Penetrate zona pellucida
B) Penetrate corona radiata
C) Fusion of plasma membranes of oocyte and sperm.
- Penetrate corona radiata
- Penetrate zona pellucida
- Fusion of plasma membranes
The head of the sperm is covered with ______, which releases hydrolytic enzymes to dissolve the zona pellucida around the egg.
acrosome
During fusion of plasma membranes of the egg and sperm, the ______ and ______ of the sperm remains behind.
plasma membrane and mitochondria
When the first sperm touches the oocyte, the plasma membrane of the oocyte depolarises. ___________ will release enzymes to cause the zona pellucida to become impenetrable to other sperms. These prevent _______.
Cortical granules will release enzymes; preventing polyspermy
Compaction occurs after the __-cell stage, where the blastomeres change their shape to tightly align themselves against each other by tight junctions to form a compact ball of cells.
8-cell
The 16-cell stage embryo is known as ______.
morula (mulberry)
Shortly after the morula (___-cell stage) enters the uterine cavity, the fluid from the uterine cavity passes through the zona pellucida to form the __________ in the morula.
blastocyst cavity
At the 16-cell stage, the blastomeres are separated into 2 parts - inner cell mass (known as _________) and outer cell mass known as __________.
ICM - embryoblasts
outer cell mass - trophoblast
5 days after fertilisation, the blastocyst hatches out of the ________, and is ready for implantation.
zona pellucida
Implantation refers to the blastocyst attaching itself to the ___________.
endometrium epithelium
Once implantation to the endometrium occurs, the trophoblast differentiates into 2 layers - ______ and _______.
synctiotrophoblast (outermost layer) and cytotrophoblast (inner layer)
The ________ of the blastocyst has finger-like projections which penetrate the endometrium of the uterus to implant the blastocyst.
synctiotrophoblast
________ pregnancy refers to blastocyst implant in abnormal locations outside the uterus.
Ectopic pregnancy
In the 2nd week of development, the embryoblast differentiates into 2 layers - _____ and _____. This is known as the formation of bilaminar germ disc from the embryoblast.
Epiblast (3rd) and hypoblast (4th)
A cavity known as the ______ then forms between the epiblast and the trophoblast.
amniotic cavity (lined by amnioblast cells)
Around 9 days after fertilisation, the formation of vacuoles in the _______ takes place. These vacuoles fuse to form larger _______.
formation of vacuoles takes place in the syncytiotrophoblat; they fuse to form larger lacunae
During the lacunar stage, the formation of ______ membrane also occurs. This membrane is formed by the hypoblasts cells, migrating along the internal aspect of the cytotrophoblast. The blastocyst cavity is now known as the ________/primitive yolk sac.
exocoelomic membrane
blastocyst cavity is now known as exocoelomic cavity/yolk sac.
At day 12 stage, there is further growth of the __________ erodes the maternal endometrial capillaries. That would result in early uteroplacental circulation. The blood flows into the _____ of the embryo.
growth of syncytiotrophoblast; blood flows into the lacuna
After early uteroplacental circulation, there is a formation of _______ outside the embryo, which is developed between the cytotrophoblast and the exocoelomic membrane.
The cavity develops within the mesoderm is known as ___________.
extraembryonic mesoderm
cavity - extraembryonic coelom
The extraembryonic mesoderm is divided into two parts - __________mesoderm and __________ mesoderm.
splanchnopleuric mesoderm (covering the yolk sac); somatopleuric mesoderm (Covering the cytotrophoblast)
The extraembryonic mesoderm forms a ________, which is connecting the embryo to the trophoblast. This is going to develop into the umbilical cord.
connecting stalk
At the end of week 2, the lower half of the primitive yolk sac is pinched off the form the ________ yolk sac.
secondary yolk sac
The first sign of gastrulation is the formation of the _________.
primitive streak
The primitive streak is formed by the cells of the ______ moving towards the midline, where they accumulate and form the primitive streak.
epiblast
__________ is the process of forming the three germ layers.
Gastrulation
(Gastrulation) Some of the epiblast cells displace the hypoblast cells, forming the _______.
endoderm
(Gastrulation) Other epiblast cells lie between the epiblast and the newly created endoderm, to form _______.
mesoderm
(Gastrulation) The cells that are remaining in the epiblast form the ______.
ectoderm
The ________ is formed by the mesodermal cells from the primitive pit, which migrates cranially, and form a median cellular cord. This structure defines the primitive mid line axis of the embryo.
notochord
The bilaminar prochordal plate is the future (anal/oral) office. It represents the cranial end of the embryo.
oral
The bilaminar cloacal membrane is the future (anal/oral) office. It represents the caudal end of the embryo.
anal
The notochord induces the formation of the __________, which gives rise to the brain and spinal cord.
neural plate
Which embryonic tissue gives rise to the neural plate?
A. Ectoderm
B. Mesoderm
C. Endoderm
D. Notochord
Answer: A) Ectoderm (neuroectoderm)
__________ cells are derived from the neuroectoderm.
These cells give rise to Schwann cells, sensory and autonomic ganglion, adrenal medulla and melanocytes.
Neural crest
The notochord is formed from (mesoderm/endoderm/ectoderm) tissue.
mesoderm
________ ectoderm gives rise to epidermis, hair, nails, cutaneous and mammary glands, anterior pituitary gland, enamel of teeth, inner ear and lens.
Surface ectoderm
Mesoderm will further differentiate to form three layers.
What are these three layers?
- Paraxial mesoderm
- Intermediate mesoderm
- Lateral plate mesoderm (which is divided into intraembryonic somatic mesoderm and intraembryonic viscera mesoderm)
The ________ mesoderm gives rise to the kidneys and gonads.
intermediate mesoderm
The paraxial mesoderm are organised into segments known as _________.
somites
The _______ mesoderm gives rise to the skeleton (except skull), connective tissue, skeletal muscles and dermis of the skin.
paraxial
The ___________ mesoderm gives rise to connective tissue of viscera and limbs, serous membranes of pleura, pericardium and peritoneum, blood and lymph cells, _________ and lymphatic systems.
Lateral plate mesoderm; cardiovascular system
The endoderm gives rise to the _________ of gastrointestinal tract, liver, pancreas, urinary bladder and respiratory tract.
epithelial lining
_________ period refers to the 3rd to 8th week of development post fertilisation.
This refers to the period of organogenesis.
Embryonic
The __ to __ week of embryo development is the most sensitive to outside factors, such as environmental hazards, pharmaceutical agents and drugs of abuse. (teratogens)
3rd to 8th week (embryonic period of organogenesis.)
