Definition of the Embryo and Other Pregnancy Phases

Embryos and Other Pregnancy Phases –  In the developmental stages of living things there is a term commonly referred to as an embryo. Embryo is a term that is quite popular in the language of biology, especially when studying cells and reproduction. However, even though the term embryo is very popular, many people still do not understand what an embryo means. In fact, in the stages of fetal development, it also always goes through the embryonic stages. Therefore, learning and understanding about the embryo and its stages is very important.


Embryo is a cell derived from the reproductive process of a child and a diploid eukaryote that is at an early stage of development. Because the cells are diploid in nature, this embryo is still capable of dividing up to hundreds of cells. This will remain protected in the structure of the parent organism such as seeds, mother’s womb, and eggs. For the human embryo, of course, it will be protected by the uterus of the mother who contains it.

Related to its formation, in living things that reproduce by sexual reproduction, there will be a union between female and male gametes which then forms a zygote. .

When it has become a zygote, then the cell will undergo divisions up to hundreds of cells. Then, these cells will be differentiated or separated. When these cells begin to separate, the embryonic phase or embryo formation begins to occur.


Many terms are used to talk about reproduction, for some people it might be considered confusing and difficult to understand. Usually, the word fetus is used to refer to a baby that is growing in the womb. Even so, the gestation period will go through various phases since fertilization.

Three general terms, namely zygote, embryo and fetus, are used in reproductive biology to refer to a potential baby. However, each refers to the names of the different stages a baby goes through during gestation. Knowing the difference between all these terms will be very useful to you .


When the male gamete (sperm) and female gamete (egg cell) unite, a phenomenon of fertilization occurs, which will produce a new cell. The new cell contains much of the genetic material in equal parts between the father and mother, so it contains 23 chromosomes from the father and 23 from the mother. Therefore, a zygote is the result of fertilization of an egg by a sperm.

The zygote is the first stage of life and since its formation, it is full of DNA which contains a lot of genetic information regarding various aspects of the future like the physique, for example. However, even though it is one of the most important parts of the reproductive stage, as it is the beginning of life, the new creature will be called a zygote for a short time, only about 24 hours and no more. After the first few hours have passed, the zygote will segment into cells and thus begin the next period, the embryonic period.


With cell segmentation, the second gestation period begins, which is commonly referred to as the embryonic period. This second stage of life only lasts about 8 weeks. In the case of humans, during this embryonic period, new creatures will acquire the characteristics of each species.

From the first day after the zygote stage, embryo development as well as cell division begins. As the cells increase, the various organs and tissues of the future baby will be created. Up to the next 8 weeks, the embryo will undergo various important changes that occur as a result of cell division. In fact, the embryo itself can get a different name during those first weeks.


When the embryonic stage is over, the new creature will have organs and when limbs begin to develop, this period will end, giving rise to the longest gestation in the fetal stage. From this point on, the cell will begin to specialize. Until the next few months when the baby is born, they will go on to form and develop all the tissues and organs.

Vital organs such as the brain, kidneys and liver begin to operate or function in the fetus. Besides that, the fetus will get the physical characteristics of the baby that it will carry when it is born. During these few weeks, the fetus will grow and develop fully, as long as the pregnancy is proceeding normally. In the prenatal check-up, you will be able to listen to the baby’s heartbeat, see how your future baby moves or even blinks.

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The developmental phase of the embryo has various stages in its development process. Each stage has different characteristics. This of course will affect the condition of human pregnancy and the side effects that will be felt by the mother. Here’s a full explanation.

1. Morula phase

In the morula phase, the zygote which still has a single cell will start dividing. This division is called mitotic division and will form many new cells called blastomeres. Blastomer cells are densely packed and number around 16 cells. Then, the 16 blastomer cells will gather together and form a ball-like shape called the morula. This is called morula because the shape is almost the same as the strawberry fruit which looks small and has no cavity.

2. Blastula phase

After going through the morula phase, the next development arrives at the blastula phase. In this phase, the formed morula will continue to undergo division until the number is around 100 cells. Because there are quite a lot of them, these balls will later form cavities inside which are called blastula.

The cavity that has been formed will then be renamed as the blastosol. Furthermore, the cell mass that has been formed from lactic acid, amino acids, pyruvate, and glucose will develop and form a human embryo. Then, the outermost cells that wrap the mass will develop into the placenta which has a function as a disposal of metabolic waste from the embryo.

3. Gastrula phase

In the gastrula phase, cells that have been formed in the blastula phase will undergo various reforms. From this reshuffling will produce 3 germ layers. This layer is also often referred to as the embryogenic layer which will later form the layers inside the embryo.

Following, the layers that will form in this phase are:

  • The ectoderm layer is the outermost layer of the embryo.
  • The mesoderm layer is the middle layer of the embryo.
  • The endoderm layer is the cell nucleus layer of the embryo that will develop into a fetus.

4. Organogenesis phase

The last phase of the developmental stages of the embryo is the organogenesis phase. In this phase, body cells will begin to form completely, but are formed gradually. This formation comes from the three layers of germ cells that have been formed in the previous stage. Each germ layer will form a variety of different organs in the fetus.

In detail, the following each layer will form organs, namely:

  • The extoderm layer will form the epidermis, eyes, nerves, and also the inner ear.
  • The mesoderm layer will form various muscles, blood cells, excretory system, and reproductive organs.
  • The endoderm layer will form the digestive system, lungs, pancreatic cells, thyroid gland, liver and also the reproductive organs.

That is a complete review of the various stages and phases of embryo development in human pregnancy.


For pregnant women, the health of the baby is a priority. This can be proven by how the expectant mother treats the baby who is still in her womb.

Therefore, it is not uncommon for us to find pregnant women who are busy maintaining their diet and activities just for the health of the baby they are carrying.

Not only that, checking with an obstetrician regularly is also a form of effort that the expectant mother makes to maintain the health of her beloved baby.

Even though you have done various ways to maintain the health of the fetus in the womb, what’s the point if you don’t know the specific health condition of your baby. The following is a list of the characteristics of healthy content that you need to understand

1. There is an increase in body weight

When you realize when you gain tens of kilograms of weight during pregnancy, don’t feel sad! Instead, you should be happy, because the increase in weight indicates that your baby is growing healthily in the womb. Ideally, you will experience a weight gain of around 13 to 15 kilograms during pregnancy.

Well, if this happens, then you can be sure that the baby you are carrying is in a healthy condition. Even so, the increase in weight can vary, depending on whether you were overweight before pregnancy or not.

In any case, if the mother is able to maintain the figure determined by the doctor, then it can be ensured that the fetus is growing quite healthy.

2. Hormone levels

Every woman who is pregnant, her body will also experience hormonal changes. It is important for mothers to understand that the levels of estrogen and progesterone in the body have a very big influence on the overall health of the baby.

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Basically, pregnant women will produce around 400 mg of progesterone cells. In contrast to the growth of the uterus, in order to support a healthy baby, you need about 1,200 grams of estrogen cells in your body.

3. Development of the mother’s stomach

It is true that every woman who is pregnant will have a different size and shape of the stomach.

Mothers can consult an obstetrician regarding the shape and size of the abdomen in order to ascertain the health condition of the fetus.

Therefore, it is important for you to have regular consultations with your doctor to find out the health condition of your baby.

4. Steady heart rate

As with humans in general, the fetal heart rate is very influential on the overall health of the prospective baby.

In general, the fetal heart rate is between 110 and 160 beats per minute. To find out and monitor the fetal heart rate, you can do it anywhere as long as you have entered the last trimester of pregnancy.

5. Movement of the fetus in the stomach

Logically, the movements that the baby makes are one way for the fetus to communicate with its mother. Generally, this movement begins to be felt when you enter the last trimester of pregnancy.

Over time, you will feel a few small kicks from the baby.

The nature, type, and intensity of movements experienced by pregnant women can actually vary.

Even so, any form of movement in the womb is an indication that the baby can receive the optimal amount of oxygen and various other important nutrients for its growth.

6. The baby’s movements will decrease before birth

After understanding the importance of fetal movement, then after that you will experience a phase of decreased fetal movement during the final semester of pregnancy.

No need to worry, because this is actually a sign that the pregnancy and fetus of the birth mother are in a healthy condition. However, you still have to be vigilant if the fetus doesn’t move at all within a few hours.

7. There is still amniotic fluid

During an ultrasound examination, it is also important for the doctor to know the amount of amniotic fluid in the mother’s womb.

The amniotic fluid itself has many roles for the fetus, from protecting the fetus to functioning so that the fetus can move easily in the womb.

If the amniotic fluid has run out or the mother is experiencing leakage of amniotic fluid, then this can be risky for the mother and the baby to cause infection in the womb.

So, those are seven signs of a healthy fetus in the womb that you can pay attention to.

Before carrying out the examination, also make sure that the mother has maintained a good body condition and diet so that the future baby can develop and grow healthily.


Maintaining pregnancy can be done by living a healthy lifestyle. However, it needs extra different treatment compared to when you are not pregnant.

Here are some ways to keep your pregnancy healthy:

1. Regularly check with the doctor

One way to keep your pregnancy healthy is to regularly check with your doctor.

When you find out that you are pregnant, immediately check with your doctor to find out your body’s condition. The doctor will schedule regular visits to see the condition of the mother and the development of the fetus. These visits can help prevent birth defects.

2. Healthy food

Eating a healthy diet can help to maintain a healthy pregnancy. Foods that have a high nutritional content can be associated with healthy brain development and baby weight. Important nutrients needed during pregnancy include foods that contain protein, calcium, vitamin C, iron, and folic acid.

3. What should not be eaten

A number of foods can also be linked to poor fetal development because they contain bacteria and parasites. Don’t eat food that is not cooked, food that has been cold for too long, and food that is burned until it turns black. Pregnant women are also prohibited from consuming unpasteurized cheese or milk.

4. Consume vitamins

Pregnant women need additional vitamin nutrition to keep their pregnancy strong and healthy. The most needed vitamins are B vitamins or folic acid. Consult a doctor to get vitamins that suit your body condition.

5. Sports

Pregnant women are also advised to continue exercising with light to moderate intensity. Choose sports that are safe for pregnant women, such as yoga. Exercise helps mothers sleep better, strengthens muscles, and reduces back pain.


6. Smoking and alcohol consumption are prohibited

Smoking and consuming alcohol can harm the health of the fetus. Not only that, inhaling cigarette smoke or being a passive smoker also has an adverse impact on fetal development.

7. Vaccines and health protocols

In the midst of the Covid-19 pandemic, pregnant women also need to get complete vaccinations immediately and always implement health protocols to maintain the health of the mother and prospective baby.

That’s how to keep pregnancy healthy.