Fertilization Process Quiz

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.