Fertilisation to Trilaminar Embryology
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Questions and Answers

Which cell type produces hCG?

  • Cytotrophoblast
  • Syncytioblast (correct)
  • Epiblast
  • Hypoblast

On which day is implantation complete?

  • Day 9 (correct)
  • Day 12
  • Day 13
  • Day 14

Which cavity forms from the epiblast?

  • Chorionic cavity
  • Amniotic cavity (correct)
  • Primitive yolk sac
  • Definitive yolk sac

Which germ layer gives rise to the nervous system?

<p>Ectoderm (B)</p> Signup and view all the answers

Which mesoderm layer is responsible for the urogenital systems?

<p>Intermediate mesoderm (C)</p> Signup and view all the answers

Which layer of the lateral plate mesoderm forms the dermis and lining of body wall?

<p>Somatic layer (C)</p> Signup and view all the answers

Which germ layer gives rise to the lining of the gut tube?

<p>Endoderm (C)</p> Signup and view all the answers

Which germ layer gives rise to the epidermis of the skin?

<p>Ectoderm (B)</p> Signup and view all the answers

Which cavity develops from the extraembryonic mesoderm and later forms the umbilical cord?

<p>Chorionic cavity (D)</p> Signup and view all the answers

Which structure facilitates implantation and the formation of the placenta?

<p>Trophoblast (C)</p> Signup and view all the answers

During fertilization, what triggers the completion of meiosis 2 in the egg?

<p>Sperm entry into the egg (B)</p> Signup and view all the answers

What is the function of cortical granules released by the oocyte during fertilization?

<p>To make the zona pellucida impenetrable to other sperm (D)</p> Signup and view all the answers

What is the name of the process where the one-cell embryo undergoes a series of cleavage divisions?

<p>Cleavage (C)</p> Signup and view all the answers

What is the main difference between the trophoblast and the embryoblast in the blastocyst?

<p>Trophoblast contacts with the endometrium, while the embryoblast is responsible for the formation of the embryo (D)</p> Signup and view all the answers

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?

<p>Compaction (D)</p> Signup and view all the answers

What is the term for the process where the blastocyst implants into the endometrial lining of the uterus?

<p>Implantation (D)</p> Signup and view all the answers

What is the term for the condition where implantation occurs outside the uterus?

<p>Ectopic pregnancy (D)</p> Signup and view all the answers

What is the term for the condition where the placenta lies low in the uterus and partially or completely covers the cervix?

<p>Placenta previa (D)</p> Signup and view all the answers

During fertilization, what is the function of the acrosomal enzymes released from the sperm head?

<p>To digest its way into the egg (C)</p> Signup and view all the answers

Which layer of the lateral plate mesoderm forms the dermis and lining of the body wall?

<p>Somatic mesoderm (D)</p> Signup and view all the answers

During gastrulation, the epiblast cells invaginate through the primitive streak to form which of the following?

<p>Three primary germ layers (C)</p> Signup and view all the answers

What is the purpose of the acrosomal enzymes released from the sperm head during fertilization?

<p>The acrosomal enzymes released from the sperm head help the sperm digest its way into the egg.</p> Signup and view all the answers

What triggers the completion of meiosis 2 in the egg during fertilization?

<p>The entry of the sperm triggers the completion of meiosis 2 in the egg.</p> Signup and view all the answers

What is the composition of the blastocyst?

<p>The blastocyst is comprised of two different cell types: the outer cell mass (trophoblast) and the inner cell mass (embryoblast).</p> Signup and view all the answers

What is the role of the trophoblast in the blastocyst?

<p>The trophoblast contacts with the endometrium of the uterus to facilitate implantation and the formation of the placenta.</p> Signup and view all the answers

What is the role of the embryoblast in the blastocyst?

<p>The embryoblast is responsible for the formation of the embryo itself.</p> Signup and view all the answers

Where does the blastocyst implant in the uterus?

<p>The blastocyst implants into the endometrial lining on the posterior or anterior uterine wall.</p> Signup and view all the answers

What are the two cavities formed on Day 9 of embryonic development?

<p>amniotic cavity (epiblast) and primitive yolk sac (hypoblast)</p> Signup and view all the answers

What is the name of the cavity that forms on Day 12 and later develops into the umbilical cord?

<p>chorionic cavity</p> Signup and view all the answers

What are the three primary germ layers formed during gastrulation?

<p>ectoderm, mesoderm, endoderm</p> Signup and view all the answers

What structures are derived from the ectoderm?

<p>epidermis of skin, hair, nails and nervous system</p> Signup and view all the answers

What structures are derived from the mesoderm?

<p>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)</p> Signup and view all the answers

What structures are derived from the endoderm?

<p>lining of gut tube, lining of respiratory tract, lining of bladder and urethra</p> Signup and view all the answers

What is the process called when the blastocyst implants into the endometrial lining of the uterus?

<p>implantation</p> Signup and view all the answers

What is the function of the zona pellucida glycoprotein layer?

<p>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.</p> Signup and view all the answers

What enzymes does the acrosome produce and what is their purpose?

<p>Hyaluronidase and acrosin are two acrosomal enzymes that are degradative as they break down the outer membrane of the ovum- zona pellucida.</p> Signup and view all the answers

What happens on day 7.5 after fertilisation?

<ul> <li>Trophoblast divides into cytotrophoblast (individual cells) and syncytioblast (single multinucleated cell which produces hCG)</li> <li>Embryobast divides into epiblast (dorsal surface) and hypoblast (ventral surface)</li> <li>Amniotic cavity begins to form</li> </ul> Signup and view all the answers

What happens on day 9 after fertilisation?

<ul> <li>Formation of 2 cavities = amniotic cavity (epiblast) and primitive yolk sac (hypoblast)</li> <li>Implantation complete</li> </ul> Signup and view all the answers

What happens on day 12 after fertilisation?

<ul> <li>Uteroplacental circulation established -Maternal blood flows into the lacunae (gaps in the the trophoblast) to diffuse to the embryoblast</li> <li>Extraembryonic mesoderm develops then degenerates, forming chorionic cavity</li> </ul> Signup and view all the answers

What happens on day 13 after fertilisation?

<ul> <li>Further development of chorionic cavity</li> <li>Presence of connecting stalk (later umbilical cord)</li> <li>Second wave of hypoblast cells migrate to form definitive (secondary) yolk sac</li> </ul> Signup and view all the answers

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