Good looks are still useful! Embryo beauty contest: Embryo appearance and selection

Author: Fu Jing, Chief Physician of Shanghai Jiai Genetics and Infertility Diagnosis and Treatment Center

Reviewer: Sun Xiaoxi, Chief Physician, Obstetrics and Gynecology Hospital, Fudan University

"China's Idol Producer" vs. "Korea's Idol Producer"! In this era of "70% depends on appearance and 30% depends on luck", no matter what age, good-looking is an advantage! And good-looking child stars can often grow up to be superstars! For example, "Da Mi Mi"... Speaking of appearance, does the "involution" also start from the embryo? Today, let's take a deep look at the appearance and selection of embryos!

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Ever since the egg emerged from the mother's ovary, she has embarked on the gorgeous transformation journey of "Idol Trainee" (from fertilization to embryonic development).

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In the 3-5 days of temporarily leaving their mothers, they have no time to rest in order to eventually grow into the "idols" that the world pays attention to. First, the eggs have to meet the true love prince (sperm) and become a brand new individual - the fertilized egg. The fertilized egg is an upgraded version of the egg. It will have two sets of genetic systems from the father and mother. In the process of growing into an early embryo, it will also have its own unique genetic code. From the one cell of the fertilized egg to the first division into two cells, and then to the second and third divisions, finally on the third day after the egg retrieval, it will turn gorgeously and become an early embryo, meeting its parents for the first time.

Although there is a slight error in judging by appearance alone, the fastest and most effective non-invasive method for selecting embryos is still clinically recognized as "embryo morphological analysis", that is, face recognition! Embryologists usually score embryos according to the internationally recognized universal morphological scoring system.

So, what are the scoring criteria?

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Grade I: Each dividing cell is uniform in size, with no fragments or fragments ranging from 0 to 5%.

Level II: Each dividing cell is of uniform size, and the proportion of fragments is between 5% and 20%.

Grade III: The size of each dividing cell is obviously uneven, or the proportion of fragments is between 21% and 50%, and there are vacuoles.

Grade IV: The size of each dividing cell is seriously uneven, the proportion of fragments is more than 50%, and there are many vacuoles.

So, how to choose "idol" embryos?

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The embryos on the third day after egg retrieval are usually 6 to 8 cells, and grades I to III are usable, while 5 cells and below or grade IV are unusable embryos. If the doctor says "8/Ⅱ" on the third day, it means 8 cells grade II, and embryos above 7 cells grade II are all "idol" embryos with high "value"!

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Where is the future of Idol Producer? — Where did the embryos go?

① If the indicators of endometrium and various hormones are suitable for transplantation, the doctor will choose "high-value" idol embryos for transplantation to increase the success rate of IVF.

② If the doctor assesses that the current uterine condition is not suitable for implantation, the qualified embryos (grades I and II, 6 to 8 cells) will be frozen and revived for transplantation at the next appropriate time.

③If there are too many available embryos or the overall quality is poor, we may extend the in vitro culture time to the 5th or 6th day after egg retrieval to conduct further natural selection of embryos and obtain "high-value" idol blastocysts. The implantation rate of blastocysts will also be significantly higher than on the third day!

Of course, blastocyst culture also has certain risks. Some embryos may not have the ability to continue to develop and cannot form blastocysts. Therefore, the doctor will make a comprehensive consideration based on the patient's condition in order to make a choice.

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After 5-6 days of idol training, the embryo baby is getting stronger and stronger! When it comes to listening to the blastocyst report, many parents are confused and say they don’t understand the classification codes of various blastocysts.

So, what exactly is a blastocyst?

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Let's first talk about the basic process of IVF: ovulation induction - egg retrieval - sperm retrieval - in vitro fertilization - embryo culture. The embryo formed on the first day after in vitro fertilization is called a "fertilized egg", the second to fourth days are "cleavage stage embryos", and the embryo formed on the fifth to sixth days is called a "blastocyst" .

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Blastocyst, as the name implies, is an embryo with a cystic cavity, and its appearance is like a large water sac. Blastocyst is an embryo with many cells. Blastocyst cells are divided into trophectoderm cells (which later differentiate into the placenta part) and inner cell mass (which later differentiate into the fetus part) according to the different parts of the subsequent differentiation. Both parts of cells are very important, and they can only be implanted in the uterine cavity if they grow and develop normally. In addition to these two types of cells, the middle part is filled with liquid, which is the "cystic cavity", and these liquids are "cystic cavity fluid".

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Is “blastocyst” really a “male embryo”?

Blastocysts can be divided into "male embryos" and "female embryos" according to their gender. However, only gender-related genetic diseases, such as hemophilia, can be screened for the gender of blastocysts. Any non-medical fetal gender identification and selection is prohibited .

In other cases, blastocysts can only be divided into good quality blastocysts and poor quality blastocysts, which are mainly evaluated based on the growth of the blastocyst, the size of the cyst cavity, whether it is expanded, and the morphology and number of trophoblast cells and inner cell mass.

Of course, there are also patients who undergo third-generation test tubes. This is mainly because at least one of the couple has chromosomal abnormalities or single-gene genetic diseases, repeated unexplained miscarriages or repeated implantation failures, and the endometrium is relatively normal to consider embryo factors, or they are at high risk of chromosomal abnormalities at an advanced age. A biopsy of the blastocyst trophoblast cells can be performed to screen out normal blastocysts in order to increase the implantation rate and achieve the goal of eugenics.

How to choose the “idol” blastocyst?

What does the series of letter + number combinations that the doctor reports like a verification code during a conversation mean?

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Take B4BB as an example: the first B stands for blastocyst; the second number 4 represents that the developmental stage of this blastocyst is the 4th stage (that is, the expanded blastocyst); the third letter B represents the level of the inner cell mass (A or B is relatively excellent, C is slightly worse); the fourth letter B represents the level of the trophoblast cells (also A or B is relatively excellent, C is slightly worse).

As long as one of the 3rd and 4th letters is B or above, it is a usable blastocyst. If the 3rd and 4th letters are both C, then the quality of the blastocyst is very poor and it is an unusable blastocyst.

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Why is my blastocyst code so short? ——What do B1 and B2 mean?

Here, 1 and 2 represent early blastocysts with relatively small cyst cavities. If it is the 5th day after IVF, we will continue to culture them. If they still develop to stage 4 and at least one of the inner cell mass or trophoblast cells is at level B or above, they are all usable blastocysts. If the blastocysts are still at stage B1 or B2 on the 6th day, they have lost their growth vitality and become unusable blastocysts.

If you encounter a B3 blastocyst, it means that its development stage is stage 3, which means that the cyst cavity is large enough, but the entire blastocyst has not expanded. As long as you see that at least one of the two letters behind it is B or above, it is a usable blastocyst! If it is B5 or B6, it means that the blastocyst has been partially or fully hatched (PS: The hatching of the blastocyst means that the outer coat of the water sac is broken by the growing cyst cavity, indicating that the blastocyst is growing). Usually, such blastocysts are encountered when doing third-generation test tubes, because these embryos will be artificially hatched in advance (that is, a small hole is made in the outer coat of the embryo with a laser to help the trophoblast cells hatch) to facilitate biopsy.

If the doctor assesses that the current uterine condition is not suitable for implantation, the qualified embryos (grades I and II, 6 to 8 cells) will be frozen and revived for transplantation at the next appropriate time.