Let’s get started.<\/p>\n\n\n\n
![\"Embryo](\"https:\/\/alexroblesmd.com\/wp-content\/uploads\/2021\/07\/embryo-development.png\")
<\/figure><\/div>\n\n\n\n\n\nWhat are the stages of embryo development in IVF?<\/h2>\n\n\n\n
There are 3 main stages of human embryo development: the cleavage stage, the morula, and the blastocyst.<\/p>\n\n\n\n
Ideally, this process should take 5 to 6 days, but it can take up to 7 days.<\/p>\n\n\n\n
Let’s go over these stages day by day.<\/p>\n\n\n\n
![\"stages](\"https:\/\/alexroblesmd.com\/wp-content\/uploads\/2021\/07\/stages-of-embryo-development.png\")
<\/figure><\/div>\n\n\n\nDay 0:<\/strong><\/h3>\n\n\n\nDay 0 is the day of the egg retrieval.<\/a><\/p>\n\n\n\nAfter your eggs are retrieved, the embryologist will examine the eggs and determine how many of them are mature.<\/p>\n\n\n\n
The mature eggs will then be combined with sperm (either through conventional insemination or intracytoplasmic sperm injection (ICSI)<\/a>) and incubated overnight in the IVF lab.<\/p>\n\n\n\nDay 1:<\/strong><\/h3>\n\n\n\nOn the morning after your egg retrieval, we will check to see if your eggs have undergone successful fertilization.<\/p>\n\n\n\n
This simply means that the egg and the sperm have come together.<\/p>\n\n\n\n
The fertilized egg<\/a> is now called a zygote<\/strong> and it will be left in the incubator to give it the best chances of growing and dividing.<\/p>\n\n\n\nDay 2:<\/strong><\/h3>\n\n\n\nAt this point, the embryo will undergo cell division. This simply means that the one-cell zygote will divide into 2 cells. <\/p>\n\n\n\n
These two cells will then divide again making 4.<\/p>\n\n\n\n
4 will eventually make 8.<\/p>\n\n\n\n
Each individual cell is called a blastomere, and the embryo is now in the cleavage stage.<\/strong><\/p>\n\n\n\n![\"image](\"https:\/\/alexroblesmd.com\/wp-content\/uploads\/2021\/07\/2-cell-embryo.jpg\")
<\/figure><\/div>\n\n\n\nDay 3:<\/strong><\/h3>\n\n\n\nOnce the developing embryo has reached the third day, the embryologist will check on its development by physically counting the number of cells it contains.<\/p>\n\n\n\n
Depending on the time at which we look at the embryo, it can have anywhere between 8-16 blastomeres on Day 3. (The earlier in the day you look, the fewer cells it will contain).<\/p>\n\n\n\n
Cleavage stage embryos can be transferred on day 3, however, a blastocyst embryo transfer has become the gold standard in IVF<\/a>.<\/p>\n\n\n\nSystematic reviews have found significant differences in terms of implantation rates and clinical pregnancy rates between a blastocyst transfer and a cleavage stage transfer.<\/a><\/p>\n\n\n\nThere are several reasons:<\/p>\n\n\n\n
- Blastocysts have “proven” themselves and demonstrated that the have the ability to grow and divide past a certain point in the IVF lab, whereas a Day 3 embryo can still arrest.<\/li>
- Embryos that have reached the blastocyst stage of development have more likely to be genetically normal. <\/li>
- Embryos aren’t supposed to be in the uterus on the third day after normal fertilization. Cleavage-stage embryos are still in the fallopian tube and don’t arrive at the uterine lining until Day 5 or 6.<\/li><\/ul>\n\n\n\n
![\"image](\"https:\/\/alexroblesmd.com\/wp-content\/uploads\/2021\/07\/cleavage-stage-embryo.jpg\")
<\/figure><\/div>\n\n\n\nDay 4:<\/strong><\/h3>\n\n\n\nOnce the embryo contains 16 or more blastomeres, the embryo has now reached the morula stage.<\/strong><\/p>\n\n\n\nIn some cases, the embryo could even reach a stage known as an early blastocyst.<\/p>\n\n\n\n
This is when the cells begin to differentiate. I.e, you can see two completely different types of cells forming. These are known as:<\/p>\n\n\n\n
- trophectoderm cells (cells that will eventually become the placenta) and<\/li>
- inner cell mass cells (cells that will eventually become the fetus).<\/li><\/ul>\n\n\n\n
Day 5, 6, or 7:<\/strong><\/h3>\n\n\n\nAt this point, the embryo may have achieved blastulation.<\/strong> This is when you can clearly see the inner cell mass distinct from the trophectoderm.<\/p>\n\n\n\nThe embryo is now called a blastocyst<\/strong>, and it is ready for implantation.<\/p>\n\n\n\nA blastocyst can be transferred fresh (in the same menstrual cycle in which it was created), or it can be frozen for future use.<\/a> <\/p>\n\n\n\n
After your eggs are retrieved, the embryologist will examine the eggs and determine how many of them are mature.<\/p>\n\n\n\n
The mature eggs will then be combined with sperm (either through conventional insemination or intracytoplasmic sperm injection (ICSI)<\/a>) and incubated overnight in the IVF lab.<\/p>\n\n\n\n On the morning after your egg retrieval, we will check to see if your eggs have undergone successful fertilization.<\/p>\n\n\n\n This simply means that the egg and the sperm have come together.<\/p>\n\n\n\n The fertilized egg<\/a> is now called a zygote<\/strong> and it will be left in the incubator to give it the best chances of growing and dividing.<\/p>\n\n\n\n At this point, the embryo will undergo cell division. This simply means that the one-cell zygote will divide into 2 cells. <\/p>\n\n\n\n These two cells will then divide again making 4.<\/p>\n\n\n\n 4 will eventually make 8.<\/p>\n\n\n\n Each individual cell is called a blastomere, and the embryo is now in the cleavage stage.<\/strong><\/p>\n\n\n\n Once the developing embryo has reached the third day, the embryologist will check on its development by physically counting the number of cells it contains.<\/p>\n\n\n\n Depending on the time at which we look at the embryo, it can have anywhere between 8-16 blastomeres on Day 3. (The earlier in the day you look, the fewer cells it will contain).<\/p>\n\n\n\n Cleavage stage embryos can be transferred on day 3, however, a blastocyst embryo transfer has become the gold standard in IVF<\/a>.<\/p>\n\n\n\n Systematic reviews have found significant differences in terms of implantation rates and clinical pregnancy rates between a blastocyst transfer and a cleavage stage transfer.<\/a><\/p>\n\n\n\n There are several reasons:<\/p>\n\n\n\n Once the embryo contains 16 or more blastomeres, the embryo has now reached the morula stage.<\/strong><\/p>\n\n\n\n In some cases, the embryo could even reach a stage known as an early blastocyst.<\/p>\n\n\n\n This is when the cells begin to differentiate. I.e, you can see two completely different types of cells forming. These are known as:<\/p>\n\n\n\n At this point, the embryo may have achieved blastulation.<\/strong> This is when you can clearly see the inner cell mass distinct from the trophectoderm.<\/p>\n\n\n\n The embryo is now called a blastocyst<\/strong>, and it is ready for implantation.<\/p>\n\n\n\n A blastocyst can be transferred fresh (in the same menstrual cycle in which it was created), or it can be frozen for future use.<\/a> <\/p>\n\n\n\nDay 1:<\/strong><\/h3>\n\n\n\n
Day 2:<\/strong><\/h3>\n\n\n\n
<\/figure><\/div>\n\n\n\nDay 3:<\/strong><\/h3>\n\n\n\n
<\/figure><\/div>\n\n\n\nDay 4:<\/strong><\/h3>\n\n\n\n
Day 5, 6, or 7:<\/strong><\/h3>\n\n\n\n
![\"image](\"https:\/\/alexroblesmd.com\/wp-content\/uploads\/2021\/07\/blastocyst.jpg\")
<\/figure><\/div>\n\n\n\n![\"alex](\"https:\/\/alexroblesmd.com\/wp-content\/uploads\/2023\/03\/alex-robles-md.jpeg\")
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