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Questions and Answers
Match the following with their descriptions:
Match the following with their descriptions:
Morula = A ball-like structure composed of numerous cells Gastrula = Marks the transition to a multilayered embryo Zygote = First division of the fertilized egg cell Early Blastocyst = Stage that occurs after gastrulation and implantation
Match the following with their characteristics:
Match the following with their characteristics:
Morula = Approximately 1mm in diameter Gastrula = Formation of three layers: ectoderm, mesoderm, and endoderm Late Blastocyst = Stage where inner cell mass and trophoblast are clearly defined Zygote = Daughter cells continue dividing through mitosis
Match the following with their roles:
Match the following with their roles:
Morula = Composed of undifferentiated stem cells Gastrula = Cells begin to change direction and form three layers Early Blastocyst = Allows for implantation into the uterine wall Late Blastocyst = Inner cell mass gives rise to the embryo
Match the following with their stages:
Match the following with their stages:
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Match the following with their functions:
Match the following with their functions:
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Match the following with their significance:
Match the following with their significance:
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Match the following terms with their corresponding description:
Match the following terms with their corresponding description:
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Match the following stages of embryonic development with their key features:
Match the following stages of embryonic development with their key features:
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Match the layers or structures involved in embryonic development with their roles:
Match the layers or structures involved in embryonic development with their roles:
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Match the following terms related to embryonic development with their stages:
Match the following terms related to embryonic development with their stages:
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Study Notes
Embryonic development is a complex process that starts with fertilization of the egg by the sperm cell and continues until the formation of a new organism. There are several key stages in this process that involve significant changes in the structure and function of cells. These stages include the morula, gastrula, zygote, early blastocyst, and late blastocyst. Each stage represents a crucial step in the development of the embryo.
Zygote
The zygote stage is the first division of the fertilized egg cell, forming two identical cells called daughter cells. These daughter cells will continue dividing through mitosis, eventually leading to the formation of a multicellular embryo. Each daughter cell receives all the genetic material needed for the development of the entire organism, including the determination of sex and other traits.
Morula Stage
The morula stage occurs when the zygote undergoes multiple divisions, resulting in a ball-like structure composed of numerous cells. This mass of cells, known as a morula, is approximately 1mm in diameter and contains nothing more than tiny clumps of undifferentiated stem cells. At this stage, the conceptus has no regular shape as the blastomeres have not yet begun to rearrange themselves.
Gastrulation
Gastrulation marks the transition from a solid, compact structure to a multilayered embryo. During gastrulation, the cells of the morula begin to change direction and move to form three layers: the ectoderm, mesoderm, and endoderm. These layers are essential for proper development of the embryo and will give rise to various tissues, organs, and body structures.
Zona pellucida Pulling
As the inner cell mass migrates towards the inner pole of the egg during gastrulation, the zona pellucida pulls the outer layer along. This movement creates a space between the inner cell mass and the outer shell of the developing embryo, allowing the blastocoel to form. The formation of a fluid-filled cavity within the embryo allows for further growth and differentiation of cells.
Early Blastocyst Stage
After gastrulation, the embryo enters the early blastocyst stage, which involves the expansion of the embryonic cavity. This process is crucial for the formation of the trophoblast and the amniotic cavity. The outer layer of the blastocyst, the trophectoderm, becomes specialized to form the placenta, whereas the inner cell mass thickens to develop into the embryo proper.
Late Blastocyst Stage
During the late blastocyst stage, the embryo begins to flatten into a disc-shaped structure, with the inner cell mass situated in the center and the outer cell mass surrounding it. The uterine epithelium invades the outer cell mass, forming villi, which become the placental tissue. The blastocoele occupies most of the interior of the blastocyst, leaving a small central opaque region where the inner cell mass resides.
In summary, embryonic development proceeds through several stages, starting with fertilization and culminating in a complex multicellular organism. Understanding these processes provides valuable insights into life's origin and evolution.
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Description
Test your knowledge on the key stages of embryonic development from zygote to blastocyst. Learn about the processes of morula formation, gastrulation, and the formation of distinct cell layers. Understand how essential structures like the placenta and inner cell mass develop during embryogenesis.
