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Questions and Answers
What is the name of the process during which the three germ layers are formed?
What is the name of the process during which the three germ layers are formed?
What is the structure that develops from mesoderm on the cranial side and induces neurulation in the overlying ectoderm?
What is the structure that develops from mesoderm on the cranial side and induces neurulation in the overlying ectoderm?
What is the primary function of the neural crest cells?
What is the primary function of the neural crest cells?
Which of the following structures develops from the paraxial mesoderm?
Which of the following structures develops from the paraxial mesoderm?
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What is the name of the process that occurs in week 4 of development, resulting in formation of the future gut?
What is the name of the process that occurs in week 4 of development, resulting in formation of the future gut?
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What is the approximate percentage of the body that the head makes up at the end of week 5 of development?
What is the approximate percentage of the body that the head makes up at the end of week 5 of development?
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Which of the following statements is TRUE regarding the development of the placenta?
Which of the following statements is TRUE regarding the development of the placenta?
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Which of the following events occurs during the fetal period?
Which of the following events occurs during the fetal period?
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What is the main event that occurs during the beginning of the third month of development?
What is the main event that occurs during the beginning of the third month of development?
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During what developmental stage are the fingers, eyes, and ears more clearly defined?
During what developmental stage are the fingers, eyes, and ears more clearly defined?
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Which of these structures forms the extraembryonic membranes?
Which of these structures forms the extraembryonic membranes?
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What is the correct order of events in the first week of embryonic development?
What is the correct order of events in the first week of embryonic development?
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What is the process called that gives rise to blastomeres?
What is the process called that gives rise to blastomeres?
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Where does conception typically occur?
Where does conception typically occur?
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During which week does implantation occur?
During which week does implantation occur?
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Which of these structures forms the amniotic sac cavity?
Which of these structures forms the amniotic sac cavity?
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What is the function of the yolk sac in humans?
What is the function of the yolk sac in humans?
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What is the name given to the condition where a fertilized egg implants outside the uterus?
What is the name given to the condition where a fertilized egg implants outside the uterus?
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What is the primary reason why a fertilized egg that implants in the fallopian tube is likely to result in an ectopic pregnancy?
What is the primary reason why a fertilized egg that implants in the fallopian tube is likely to result in an ectopic pregnancy?
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What is the name given to the developmental stage where the inner cell mass differentiates into two layers?
What is the name given to the developmental stage where the inner cell mass differentiates into two layers?
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The embryonic stage of development occurs after the fertilization of an egg.
The embryonic stage of development occurs after the fertilization of an egg.
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Flashcards
Embryology
Embryology
The study of the origin and development of individual organisms.
Prenatal period
Prenatal period
The time period before birth, including embryonic and fetal phases.
Embryonic period
Embryonic period
The first 8 weeks of development after fertilization.
Zygote
Zygote
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Blastomeres
Blastomeres
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Morula
Morula
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Blastocyst
Blastocyst
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Trophoblast
Trophoblast
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Amniotic sac
Amniotic sac
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Bilaminar embryonic disk
Bilaminar embryonic disk
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Gastrulation
Gastrulation
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Endoderm
Endoderm
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Mesoderm
Mesoderm
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Ectoderm
Ectoderm
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Neurulation
Neurulation
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Neural tube
Neural tube
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Somites
Somites
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Intermediate mesoderm
Intermediate mesoderm
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Lateral folding
Lateral folding
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Fetal period
Fetal period
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Study Notes
Embryology and Prenatal Development
- Embryology is the study of how single individuals originate and develop.
- The prenatal period includes both embryonic and fetal stages.
- The embryonic period lasts for the first 8 weeks after fertilization.
- The fetal period follows the embryonic period, lasting approximately 30 weeks within the uterus.
- Embryonic development begins with fertilization in the lateral third of the uterine tube.
- Fertilization involves the joining of the sperm and ovum to form a zygote.
- The zygote undergoes cleavage, which are cell divisions without growth, forming blastomeres.
- The 12-16 blastomere stage is called a morula.
- The morula develops into a blastocyst, a fluid-filled structure with an outer layer (trophoblast) and inner cell mass (ICM).
- Implantation occurs on day 6, where the blastocyst attaches to the uterine wall.
- The trophoblast develops into extraembryonic membranes.
- The ICM forms the embryo itself.
Embryonic Period (First 8 Weeks)
- Key events during the first 8 weeks involve the formation of organs from 3 primary germ layers.
- Week 1: Fertilization occurs, the zygote forms, and moves towards the uterus, developing into blastomeres, morula, and eventually a blastocyst that implants in the uterine wall.
- After implantation, the blastocyst develops into trophoblast and ICM.
- Week 2: The ICM differentiates into two layers, the epiblast (top layer) and hypoblast (bottom layer). This forms the bilaminar embryonic disk.
- Week 3: The epiblast forms the amniotic sac (fluid-filled sac enclosing the embryo) and the primitive streak, initiating gastrulation. Gastrulation is the process where cells migrate inward to form the three germ layers: endoderm, mesoderm, and ectoderm. This is a fundamental event in early development.
- During week 3, the notochord and neural tube develop. The notochord is a temporary structure that establishes the body's axis. The neural tube will become the central nervous system (brain and spinal cord).
- Week 4-8: Somites (body segments) form from the paraxial mesoderm. Organs and other body structures beginning to differentiate, culminating in the formation of a recognizable embryo and a beating heart.
Fetal Period (~Weeks 9-40)
- During the fetal period, organ systems continue to develop and grow.
- Growth slows comparatively, but the fetus increases in length, size, and complexity.
- Key fetal events include sex differentiation (by 3rd month), formation of fingers, eyes, and ears, and lung development.
- By the end of the second month, all organs have begun to form.
- By the end of the third month, most organ systems continue to develop and growth occurs, with the head slightly slowing down in growth compared to the body, allowing the differentiation of specific details
- By weeks 8-40, organs continue to mature, and the fetus grows and develops into a viable infant by the end of the period.
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Description
Test your knowledge on the fundamentals of embryology and prenatal development. This quiz covers the stages of development from fertilization to implantation, including key concepts like the zygote, morula, and blastocyst. Perfect for students studying human development or related fields.
