40 Questions
Which cell type produces hCG?
Syncytioblast
On which day is implantation complete?
Day 9
Which cavity forms from the epiblast?
Amniotic cavity
Which germ layer gives rise to the nervous system?
Ectoderm
Which mesoderm layer is responsible for the urogenital systems?
Intermediate mesoderm
Which layer of the lateral plate mesoderm forms the dermis and lining of body wall?
Somatic layer
Which germ layer gives rise to the lining of the gut tube?
Endoderm
Which germ layer gives rise to the epidermis of the skin?
Ectoderm
Which cavity develops from the extraembryonic mesoderm and later forms the umbilical cord?
Chorionic cavity
Which structure facilitates implantation and the formation of the placenta?
Trophoblast
During fertilization, what triggers the completion of meiosis 2 in the egg?
Sperm entry into the egg
What is the function of cortical granules released by the oocyte during fertilization?
To make the zona pellucida impenetrable to other sperm
What is the name of the process where the one-cell embryo undergoes a series of cleavage divisions?
Cleavage
What is the main difference between the trophoblast and the embryoblast in the blastocyst?
Trophoblast contacts with the endometrium, while the embryoblast is responsible for the formation of the embryo
What is the term for the process where the one-cell embryo changes shape without increase in size within the confines of the zone pellucida?
Compaction
What is the term for the process where the blastocyst implants into the endometrial lining of the uterus?
Implantation
What is the term for the condition where implantation occurs outside the uterus?
Ectopic pregnancy
What is the term for the condition where the placenta lies low in the uterus and partially or completely covers the cervix?
Placenta previa
During fertilization, what is the function of the acrosomal enzymes released from the sperm head?
To digest its way into the egg
Which layer of the lateral plate mesoderm forms the dermis and lining of the body wall?
Somatic mesoderm
During gastrulation, the epiblast cells invaginate through the primitive streak to form which of the following?
Three primary germ layers
What is the purpose of the acrosomal enzymes released from the sperm head during fertilization?
The acrosomal enzymes released from the sperm head help the sperm digest its way into the egg.
What triggers the completion of meiosis 2 in the egg during fertilization?
The entry of the sperm triggers the completion of meiosis 2 in the egg.
What is the composition of the blastocyst?
The blastocyst is comprised of two different cell types: the outer cell mass (trophoblast) and the inner cell mass (embryoblast).
What is the role of the trophoblast in the blastocyst?
The trophoblast contacts with the endometrium of the uterus to facilitate implantation and the formation of the placenta.
What is the role of the embryoblast in the blastocyst?
The embryoblast is responsible for the formation of the embryo itself.
Where does the blastocyst implant in the uterus?
The blastocyst implants into the endometrial lining on the posterior or anterior uterine wall.
What are the two cavities formed on Day 9 of embryonic development?
amniotic cavity (epiblast) and primitive yolk sac (hypoblast)
What is the name of the cavity that forms on Day 12 and later develops into the umbilical cord?
chorionic cavity
What are the three primary germ layers formed during gastrulation?
ectoderm, mesoderm, endoderm
What structures are derived from the ectoderm?
epidermis of skin, hair, nails and nervous system
What structures are derived from the mesoderm?
paraxial mesoderm (axial skeleton, skeletal muscle), intermediate mesoderm (urogenital systems), lateral plate mesoderm (somatic layer: dermis, lining of body wall, parts of limbs and visceral layer: cardiovascular system, mesothelial covering of organs, smooth muscle)
What structures are derived from the endoderm?
lining of gut tube, lining of respiratory tract, lining of bladder and urethra
What is the process called when the blastocyst implants into the endometrial lining of the uterus?
implantation
What is the function of the zona pellucida glycoprotein layer?
The zona pellucida supports communication between oocytes and follicle cells during oogenesis; protects oocytes, eggs, and embryos during development, and regulates interactions between ovulated eggs and free-swimming sperm during and following fertilization.
What enzymes does the acrosome produce and what is their purpose?
Hyaluronidase and acrosin are two acrosomal enzymes that are degradative as they break down the outer membrane of the ovum- zona pellucida.
What happens on day 7.5 after fertilisation?
- Trophoblast divides into cytotrophoblast (individual cells) and syncytioblast (single multinucleated cell which produces hCG)
- Embryobast divides into epiblast (dorsal surface) and hypoblast (ventral surface)
- Amniotic cavity begins to form
What happens on day 9 after fertilisation?
- Formation of 2 cavities = amniotic cavity (epiblast) and primitive yolk sac (hypoblast)
- Implantation complete
What happens on day 12 after fertilisation?
- Uteroplacental circulation established -Maternal blood flows into the lacunae (gaps in the the trophoblast) to diffuse to the embryoblast
- Extraembryonic mesoderm develops then degenerates, forming chorionic cavity
What happens on day 13 after fertilisation?
- Further development of chorionic cavity
- Presence of connecting stalk (later umbilical cord)
- Second wave of hypoblast cells migrate to form definitive (secondary) yolk sac
Test your knowledge on the process of fertilisation to trilaminar development in this quiz. Explore the steps involved in fertilisation, including the binding of sperm to the zona pellucida, the release of acrosomal enzymes, and the fusion of egg and sperm plasma membranes.
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