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Questions and Answers
What is fertilization also known as?
What is fertilization also known as?
How many chromosomes are present in the fertilized egg or zygote?
How many chromosomes are present in the fertilized egg or zygote?
Which pair of chromosomes determines the sex of the baby?
Which pair of chromosomes determines the sex of the baby?
What is the average length of time for prenatal development to complete from the date of conception?
What is the average length of time for prenatal development to complete from the date of conception?
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When does the late term period occur during pregnancy?
When does the late term period occur during pregnancy?
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During which stage of the prenatal period does implantation of the blastocyst into the uterine wall occur?
During which stage of the prenatal period does implantation of the blastocyst into the uterine wall occur?
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What is the function of the trophoblast?
What is the function of the trophoblast?
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At what point does a zygote become a morula, according to the information provided?
At what point does a zygote become a morula, according to the information provided?
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Which cells develop into a large part of the placenta?
Which cells develop into a large part of the placenta?
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When does the zygote implant itself in the uterus wall?
When does the zygote implant itself in the uterus wall?
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Study Notes
Fertilization and Conception
- Fertilization, also known as conception, is the union of sperm and egg cells, marking the beginning of pregnancy.
- The process starts with the combination of sperm and ovum (sex cells) to create a single cell called a zygote.
- A zygote consists of 23 pairs of chromosomes, with one of each pair contributed by parents.
- Each egg and sperm cell has 23 chromosomes, which are threadlike structures in the nucleus that contain genetic material.
Chromosomes and Sex Determination
- Autosomes are the first 22 pairs of chromosomes.
- Sex chromosomes are the 23rd pair of chromosomes, which determines the sex of the baby.
- Female sex chromosomes are XX, while male sex chromosomes are XY.
Prenatal Period and Development
- The average length of time for prenatal development to complete is 38 weeks from the date of conception.
- Less than 37 weeks is considered preterm, while 37-41 weeks is considered normal.
- The normal length of pregnancy is divided into:
- Early term: 37 weeks to 38 weeks and 6 days.
- Full term: 39 weeks to 40 weeks and 6 days.
- Late term: 41 weeks to 41 weeks and 6 days.
Stages of Prenatal Period
- Germinal Stage: day 0 to 14 days, from fertilization to about 2 weeks of gestational age.
- During this stage, the zygote begins to divide into several cells, implants itself in the uterus wall, and develops into an embryo.
- The zygote travels down the fallopian tube, becoming a morula, then a blastocyst, and eventually burrows into the uterine wall through implantation.
- By the fifth or sixth day, the fertilized egg is known as a blastocyst, a rapidly dividing ball of cells.
- The inner group of cells will become the embryo, while the outer group will become the cells that nourish and protect it.
- Blastocyst is a fluid-filled sphere that floats freely in the uterus until the 6th day after fertilization, then implants itself in the uterine wall.
- Trophoblast cells form the outer layer of a blastocyst, providing nutrients to the embryo and developing into a large part of the placenta.
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Description
Test your knowledge on the process of fertilization, from the union of sperm and egg cells to the formation of a zygote. Understand how 23 pairs of chromosomes are contributed by parents during conception.
