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Questions and Answers
What happens to the endoderm during the development of the embryo?
What happens to the endoderm during the development of the embryo?
What is the role of lateral body folding in embryonic development?
What is the role of lateral body folding in embryonic development?
What does the connecting stalk develop into during embryonic growth?
What does the connecting stalk develop into during embryonic growth?
By which day do the anterior and posterior neuropores close during embryonic development?
By which day do the anterior and posterior neuropores close during embryonic development?
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What occurs to the gut tube during lateral body folding?
What occurs to the gut tube during lateral body folding?
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What is the primary role of the syncytiotrophoblast during implantation?
What is the primary role of the syncytiotrophoblast during implantation?
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Which germ layer does the epiblast ultimately develop into during gastrulation?
Which germ layer does the epiblast ultimately develop into during gastrulation?
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What is the significance of the notochord during embryonic development?
What is the significance of the notochord during embryonic development?
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At which stage do the three germ layers - ectoderm, mesoderm, and endoderm - get formed?
At which stage do the three germ layers - ectoderm, mesoderm, and endoderm - get formed?
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Which structure is formed by the migration of epiblast cells during gastrulation?
Which structure is formed by the migration of epiblast cells during gastrulation?
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What is the first tissue to form during the expansion of the bilaminar disc?
What is the first tissue to form during the expansion of the bilaminar disc?
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What is the primary outcome of neurulation in embryonic development?
What is the primary outcome of neurulation in embryonic development?
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When does the foetus become fully formed?
When does the foetus become fully formed?
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What is the function of somites during embryonic development?
What is the function of somites during embryonic development?
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Which of the following structures do somites NOT contribute to?
Which of the following structures do somites NOT contribute to?
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When does the first somite appear during embryonic development?
When does the first somite appear during embryonic development?
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What induces the formation of the neural plate during neurulation?
What induces the formation of the neural plate during neurulation?
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How many somites are typically present by day 30 of embryonic development?
How many somites are typically present by day 30 of embryonic development?
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Which part of the somite is responsible for forming muscle precursors?
Which part of the somite is responsible for forming muscle precursors?
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What is the fate of the anterior neuropore during embryonic development?
What is the fate of the anterior neuropore during embryonic development?
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Which of the following is a consequence of neural crest cell absence during development?
Which of the following is a consequence of neural crest cell absence during development?
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What is the primary developmental stage in which most organs are formed during pregnancy?
What is the primary developmental stage in which most organs are formed during pregnancy?
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What is the zona pellucida's role during fertilization?
What is the zona pellucida's role during fertilization?
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What can be inferred if a defect is found in one tissue during development?
What can be inferred if a defect is found in one tissue during development?
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During which phase does fertilization occur?
During which phase does fertilization occur?
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Which statement is true regarding the inner cell mass during embryonic development?
Which statement is true regarding the inner cell mass during embryonic development?
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What occurs if the inner cell mass fails to split during the twinning process?
What occurs if the inner cell mass fails to split during the twinning process?
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What is indicated by Holt-Oram syndrome in terms of structural development?
What is indicated by Holt-Oram syndrome in terms of structural development?
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What is the initial size of a zygote after fertilization?
What is the initial size of a zygote after fertilization?
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What structure is formed by the fusion of the neural folds during neurulation?
What structure is formed by the fusion of the neural folds during neurulation?
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Which germ layer is primarily responsible for developing into internal organs?
Which germ layer is primarily responsible for developing into internal organs?
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What leads to the development of spina bifida during neurulation?
What leads to the development of spina bifida during neurulation?
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Which process is described as the 'zipping up' of neural folds?
Which process is described as the 'zipping up' of neural folds?
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When does neurulation begin in human development?
When does neurulation begin in human development?
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What is the fate of the neuroectoderm during development?
What is the fate of the neuroectoderm during development?
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Which structure directly induces the ectoderm to become the neural plate?
Which structure directly induces the ectoderm to become the neural plate?
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Which of the following is NOT derived from neural crest cells?
Which of the following is NOT derived from neural crest cells?
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Study Notes
Developmental Biology Study Notes
-
Why study development?
- To understand how normal structures develop
- To understand how abnormalities arise
- To understand the positioning of adult structures
- To recognize that defects in one structure can indicate defects in other structures (e.g., Holt-Oram syndrome)
- To understand the relationship between structure/organ development for accurate diagnosis
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Range of hand abnormalities Different variations in hand structure exist.
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Phenotype and development
- Mutations in genes required during development impact the development of multiple tissues
- Understanding the relationships between development and organ systems can aid in diagnosis
- Key development stages include embryonic development, fetal development, organogenesis, placental function and abnormalities noted at birth
Human Development
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Gestation period:
- Humans require 9 months (40 weeks) to fully develop.
- First trimester is critical for body formation.
- Weeks 1-2: Blastocyst stage (early development)
- Weeks 3-8: Embryonic stage (organ development)
- Week 9 onward: Fetal stage (growth and maturation of physical processes)
- Second trimester = rapid growth of the foetus
- Third trimester = fat production and other physiological processes
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Fertilization:
- Occurs in the fallopian tube.
- Sperm penetrate the egg's protective layers.
- Fertilization triggers completion of meiosis and establishes the diploid chromosome number, determining the sex of the embryo.
- Takes approximately 4 days to reach the uterine cavity.
Early Human Development
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Stages of embryonic development:
- Zygote formation (fertilized egg)
- Morula (early cell division stage)
- Blastocyst (ball of cells with a fluid cavity)
- Inner cell mass gives rise to all cells of the body
- Various stages of cell divisions Twinning
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Twinning:
- Identical twins develop from a single fertilized egg dividing into separate structures
- Fraternal twins develop from two distinct fertilized eggs.
Post-fertilization
- Zygote: The fertilized egg
- Cleavage: Early cell divisions of the zygote
- Blastocyst stage (important for twinning): development continues
- Implantation: The blastocyst embedding itself in the uterus wall
- hCG: Hormone to confirm pregnancy
Blastocyst to Fetus Development
- Blastocyst: Early embryonic stage, which differentiates into a foetus
- Embryonic stage: A period of rapid development
- Foetal stage: Continued growth and refinement
- Stages: Fetal development occurs in three stages (9 days, 5-6 weeks, 3 months for example)
Formation of Embryo/Fetus
- Gastrulation: Cells rearrange to form three germ layers: ectoderm, mesoderm, and endoderm.
- Germ layers: These layers give rise to various tissues and organs (ectoderm to skin and nervous system, mesoderm to muscles and skeleton, and endoderm to digestive system).
- Neurulation & Neurulation: Formaiton of the neural tube and the nervous system.
- Somite formation & Somitogenesis: Formation of blocks of tissue on either side of the neural tube, that eventually develop into bones, muscles, and connective tissues.
19 days to 23 days
- Closure of the neural tube
- Formation of main body axes
- Formation of organs and tissues, notably the heart and ear
Lateral Body Folding
- Folding of the embryo causes changes in shape from a flat disc to a cylindrical structure
- The gut tube is separated from the yolk sac
- Amniotic cavity completely surrounds the embryo
Folding creates the embryo
- Further development of the embryo occurs through different phases of folding that create the basic shape and structures needed for further development.
- By day 28 of development, the majority of necessary structures have formed.
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Description
Explore the key concepts in developmental biology, focusing on the normal and abnormal development of structures. This quiz covers topics such as gestation periods, hand abnormalities, and the impact of genetic mutations on development. Understand the relationships between various organ systems and their development stages.
