The early stages of embryonic development begin with fertilization. The process of fertilization is tightly controlled to ensure that only one sperm fuses with one egg. After fertilization, the zygote undergoes cleavage to form the blastula.
By the end of the embryonic stage, most organs have started to form, although they will continue to develop and grow in the next stage (that of the fetus). As the embryo undergoes all of these changes, its cells continuously undergo mitosis, allowing the embryo to grow in size, as well as complexity.
The process of prenatal development occurs in three main stages. The first two weeks after conception are known as the germinal stage, the third through the eighth week is known as the embryonic period, and the time from the ninth week until birth is known as the fetal period.
Embryonic DevelopmentAfter the 1st month of pregnancy, the heart develops. Limbs and digits develop in the 2nd month. By the end of 1st-trimester or 3rd month all the major organ systems develop. Genital organs are visible.
After one month of pregnancy, the embryo's heart is formed. By the end of the second month of pregnancy, the foetus develops limbs and digits. By the end of 12 weeks (first trimester), most of the major organ system are formed. The limbs and the external genital organs are well developed.
Your developing baby is most vulnerable to injury during the embryo stage when organs are developing. Indeed, infections and drugs can cause the greatest damage when exposure occurs two to 10 weeks after conception. Diabetes and obesity can possibly increase your child's risk of birth defects.
The Embryonic PeriodIt lasts from the third through the eighth week after conception. During this period, cells continue to differentiate and at 22 days after conception the neural tube forms which will become the brain and spinal column.
1 : of or relating to an embryo. 2 : being in an early stage of development : incipient, rudimentary an embryonic plan.
The embryonic period is the most critical period of development because of the formation of internal and external structures.
An embryo is the early stage of development of a multicellular organism. In general, in organisms that reproduce sexually, embryonic development is the part of the life cycle that begins just after fertilization and continues through the formation of body structures, such as tissues and organs.
(A) Correct sequence in development is Fertilization → Zygote → Cleavage → Morula → Blastula → Gastrula.
The heart of an embryo starts beating at about week 5 of pregnancy. It may be possible to detect, at this point, using vaginal ultrasound. Throughout the pregnancy and delivery, healthcare providers monitor the heartbeat of the fetus. Anyone who has concerns about the fetal heartbeat should contact a doctor.
If the egg is fertilized by a sperm cell, it is known as a zygote. The zygote divides and becomes a collection of cells known as a blastocyst. The blastocyst is considered an embryo at the point when the amniotic sac develops (by about day 10 to 12 after fertilization, or at the start of week #5 of pregnancy).
