Podcast
Questions and Answers
Which layer of the trophoblast differentiates into two layers during day 8 of development?
Which layer of the trophoblast differentiates into two layers during day 8 of development?
- Trophoblast (correct)
- Blastocyst
- Syncytiotrophoblast
- Embryoblast
The cytotrophoblast is a multinucleated zone without clear cell boundaries.
The cytotrophoblast is a multinucleated zone without clear cell boundaries.
False (B)
What are the two layers that the embryoblast differentiates into during day 8?
What are the two layers that the embryoblast differentiates into during day 8?
Hypoblast and epiblast
The ______ is partially embedded in the endometrial stroma on day 8 of development.
The ______ is partially embedded in the endometrial stroma on day 8 of development.
Match the following structures with their correct description on day 8 of development:
Match the following structures with their correct description on day 8 of development:
What is the flat disc formed by the two layers of the embryoblast during day 8 called?
What is the flat disc formed by the two layers of the embryoblast during day 8 called?
The cells in the cytotrophoblast divide and migrate into the syncytiotrophoblast on day 8.
The cells in the cytotrophoblast divide and migrate into the syncytiotrophoblast on day 8.
What is the small cavity that appears within the epiblast during day 8?
What is the small cavity that appears within the epiblast during day 8?
On day 8, the blastocyst is _____.
On day 8, the blastocyst is _____.
The exocoelomic membrane is formed by the cytotrophoblast.
The exocoelomic membrane is formed by the cytotrophoblast.
What is the name of the cavity that forms within the blastocyst on day 8?
What is the name of the cavity that forms within the blastocyst on day 8?
The vacuoles that appear in the syncytiotrophoblast on day 8 eventually merge to form large ______.
The vacuoles that appear in the syncytiotrophoblast on day 8 eventually merge to form large ______.
Match the germinal layer with its derived structure:
Match the germinal layer with its derived structure:
What are the two layers that the trophoblast differentiates into?
What are the two layers that the trophoblast differentiates into?
The amniotic cavity is formed within the epiblast.
The amniotic cavity is formed within the epiblast.
What is the name of the thin membrane formed by the hypoblast?
What is the name of the thin membrane formed by the hypoblast?
The _____ cells near the cytotrophoblast are called amnioblasts.
The _____ cells near the cytotrophoblast are called amnioblasts.
Match the following terms with their descriptions:
Match the following terms with their descriptions:
What happens to the vacuoles within the syncytiotrophoblast?
What happens to the vacuoles within the syncytiotrophoblast?
The blastocyst becomes deeply embedded in the endometrium by day 9.
The blastocyst becomes deeply embedded in the endometrium by day 9.
What is the name of the defect in the surface epithelium that is closed by a fibrin coagulum during implantation?
What is the name of the defect in the surface epithelium that is closed by a fibrin coagulum during implantation?
Flashcards
Exocoelomic Membrane
Exocoelomic Membrane
A membrane formed by the fusion of vacuoles in the syncytiotrophoblast, contributing to the formation of the primitive yolk sac.
Exocoelomic Cavity
Exocoelomic Cavity
The space within the exocoelomic membrane, also known as the primitive yolk sac, important for early embryonic development.
Hypoblast
Hypoblast
A layer of flattened cells that forms the inner lining of the exocoelomic cavity and contributes to the formation of the yolk sac.
Syncytiotrophoblast
Syncytiotrophoblast
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Heuser's Membrane
Heuser's Membrane
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Blastocyst
Blastocyst
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Day 8 development
Day 8 development
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Trophoblast layers
Trophoblast layers
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Cytotrophoblast
Cytotrophoblast
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Embryoblast
Embryoblast
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Epiblast
Epiblast
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Amniotic cavity
Amniotic cavity
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Amnioblasts
Amnioblasts
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Lacunar stage
Lacunar stage
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Study Notes
Presenter Information
- Presenter: Dr. Eman El Sawaf
- Affiliation: Anatomy & Embryology Department, Faculty of Medicine, Helwan University
Topic Overview
- Module: Basic Medical Science II
- Subtopic: Anatomy and General Embryology
Embryological Development
- The presentation focuses on development events during the second week (days 8 and 9) of gestation
- Specifically, the topic covers the bilaminar germ disc stage of embryonic development
Day 8 Blastocyst
- Implantation: The blastocyst is partially embedded into the endometrial stroma.
- Trophoblast differentiation: The trophoblast differentiates into two layers:
- Cytotrophoblast (mononucleated cells)
- Syncytiotrophoblast (multinucleated zone without clear cell boundaries)
- Embryoblast differentiation: The inner cell mass (embryoblast) differentiates into two layers:
- Hypoblast (small cuboidal cells near the blastocyst cavity)
- Epiblast (high columnar cells near the amniotic cavity)
- Formation of the Bilaminar embryonic disc: The two layers (hypoblast and epiblast) form a flat disc
- Amniotic Cavity Formation: A small cavity appears within the epiblast, growing to become the amniotic cavity. Cells near the cytotrophoblast are called amnioblasts
Day 9 Blastocyst
- Implantation: The blastocyst is deeply embedded within the endometrium.
- Defect closure: The penetration defect in the surface epithelium is closed by a fibrin coagulum.
- Syncytiotrophoblast vacuoles: Vacuoles appear in the syncytiotrophoblast.
- Formation of large lacunae: When the vacuoles fuse, they form large lacunae.
- Lacunar stage: This marks a stage in the formation of the embryonic circulation.
- Exocoelomic membrane: The hypoblast forms a thin membrane called the exocoelomic (Heuser) membrane, (flattened cells).
- Exocoelomic cavity (primitive yolk sac): The exocoelomic membrane delineates the exocoelomic cavity, which is the primitive yolk sac.
Other Important Points
- Objectives: Students should be able to describe the events in the second week of development.
- Reference: Langman's Medical Embryology 13th Edition by T.W. Sadler is cited as a reference source.
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