An embryo is, quite literally, the earliest form of human life. It is what is created when a sperm fertilizes an egg. A lot of people use the term embryo and egg interchangeably. They differ in that an egg is not fertilized, and therefore, is not life. The man and the woman, or in this case, their "contributions" to the baby making process, have not come together yet. The embryo is created when the sperm successfully penetrates the egg and fertilizes it and human life begins. It gets a little confusing though because "eggish" terms are used to explain embryos, namely "shell" and "hatching."
An embryo begins as one single cell. The one-celled embryo is called a zygote. The next day, it multiplies to 2 cells and then 4 cells. Then it is called a morula. The third day, it multiplies to 8 cells. By day 5, the cells have multiplied so many times that they all blend together under the microscope and you can't distinguish one cell from another because there are so many. When the embryo reaches this stage, it is called a Blastocyst.
Embryo Transfers are usually done on Day 3 or Day 5. They used to do them on Day 1 and 2 but that is less practiced now. These are also the same days on which embryos can be frozen. For some reason, they don't do transfers or freeze them on Day 4. It has something to do with what's happening in the embryo at that stage of development and you can't interrupt it. Our embryos have always been day 5 embryos. They have been frozen on the 5th day. When they are thawed, the 5th day "resumes" (even if it is now, years later) and then the transfer is later that same day. From all they can tell, there is no difference between 1 day frozen and 10 years frozen. For all intents and purposes, it appears that time quite literally stops.
When an embryo reaches Blastocyst Stage, it needs to break through the "shell" or "ring" you see in the photos above. When it has broken out, the embryo can then grab on to the wall of the uterus and implant and grow in pregnancy. If it doesn't break out, it can't "stick" to the uterus and grow. The breaking out process is called "hatching." As the embryo grows, it becomes a fetus. Ethically, they all mean "baby," or "human," but they describe different ages, much like "toddler" and "teenager" and "elderly."
This is also why the procedure to put the embryo in the woman's body is called a "Transfer" and not an Implantation. They are quite literally "transferring" (moving) the embryo from the vial it was frozen in to the woman's uterus. Whether it actually implants (grabs on, nestles in, burrows down) is up to the embryo and God. It's the same in spontaneously occurring pregnancy. The baby can be made, but it still may or may not implant--it orbits around in the uterus looking for a place to grab on, but it may or may not actually do so. In a Frozen Embryo Transfer, the doctor will "aim" the embryo for the part of the uterus that looks the most favorable, but that's as far as he can take it.
This is a super awesome chart. Enlarge it to read all the way cool information.
Embryos are graded on a scale. There are a few types of systems, but the two clinics we've used and the 3 clinics from our genetic families have all used the same system. My understanding is that this one is the most common. There is a different system for day 3 embryos but I am not familiar with it.
The 5 Day Embryo grading format is Number-Letter-Letter.
The number is a number from a scale of 1-5, with 5 being the most desirable. It indicates the degree to which the embryo has expanded inside its "shell," called the Trophectoderm. A 1 means it hasn't expanded or isn't growing. A 5 means it has hatched out. Our embryo was a 3, meaning it filled 70% of its shell.
Then an embryo receives a letter grading of A-C for the quality of the "Inner Cell Mass" which are the cells that are the baby.
- A means that there are many cells, tightly packed (this is what they should be doing).
- B means that there are several cells, loosely packed.
- C means that there are very few large cells.
Then it receives a second letter grading of A-C. This grades the quality of the Trophectoderm, the part that in the pictures looks like a shell. The Trophectoderm is what becomes the placenta in the event of implantation.
- A means that there are many cells forming a cohesive layer.
- B means that there are few cells, forming a loose layer.
- C means that there are very few large cells.
Our embryo was graded 3AA. Seventy percent expanded, great inner cell mass, great Trophectoderm.
Ethically, these grades don't really mean anything. As long as any cells are alive, I believe an embryo should be transferred. I don't think grades should ever be used to make life or death decisions. But the numbers do tell us where the embryo is at in its stage of development, which I find interesting.
So here is our photo, explained. Though it received a 3AA Grading, the grading was made as soon as it was thawed and the photo was taken a little later. In Reproductive technology, an embryologist will often perform what is called "Assisted Hatching," wherein they make a tiny hole in the Trophectoderm to let the embryo out. That, to my understanding, is what is happening in this photo. The inner cell mass has broken through the Trophectoderm and hatched, and will hopefully be looking for someplace in my uterus to grab on to. The "ring" around the Trophectoderm, is, if I recall correctly, the solution in the dish, and not part of the embryo.
None of my embryo photos have ever looked like this one before. I don't know if mine have never hatched this much, or if this photo was just taken later than the other ones have been taken. The camera is different, so perhaps the process is different. This doesn't really match up to 3AA because 3 means not hatched, so I think the difference is just time.
For reference sake, these were my other embryo photos. This is a great example of how grades don't necessarily correspond to likelihood of further growth or pregnancy. I don't even remember the grades they all got, but they look so different. Lucy and Mary don't look super expanded at time of thaw, but eventually hatched and successfully implanted. Transfer 2's babies totally filled their cavities, but couldn't implant. Matthew looks "average" in expansion and he's happy and healthy here today. Transfer 4 looked great with nice big masses, but didn't result in a pregnancy. So we'll see what happens with this baby. Nevertheless, I'm super intrigued by all the nuances and highly precise information. These babies multiply and divide and grow so aggressively, I just can't understand how anyone thinks they aren't human life. If that's not life with a desire to keep on living, I don't know what is.
So anyway, there's the skinny on all the stuff you never wanted to know about Embryology.
I was pretty drugged up when I posted my last post, so I didn't include details about the transfer itself. Here we go, if you're interested.
The transfer went well. My doctor is a man of few words. I wish I had asked more questions, but the Valium they give you to relax your uterus really puts me out of it. When he told us that one had died in thawing, it was a little like a kick in the gut. In 5 transfers, we've never lost one that way. But he told me as he was lying me down for the transfer so I didn't get to ask any questions or really digest the information. One baby living and one baby dying happened with Matthew--it's a bittersweet thing to digest. I don't want to get myself too upset because my body just needs to chill right now, so I think God is being gracious in keeping that process "shelved" for now. We are sad, but I am comforted to know that baby is with Jesus. He said the transfer went well. It was the quickest and physically easiest one I've ever had. The only thing he really said was that my C-Section scar wasn't in the way. Honestly, the weirdest things are compliments when dealing with infertility ;)
Here is a video if you want to watch. We've never taken video before but we decided that if this worked, when we tell Matthew, we wanted to have something to show him if he wanted.
Watch the area where the red circle is on this still image. You'll see the catheter come in, the embryo released from the catheter, and then the catheter will be removed and the embryo will remain behind, shown as a white oblong shape on the screen. The white is not the embryo itself, but the air the embryo was in. They put them in a little air bubble, in part so that they can see them when doing this procedure because they're so tiny. The black sort of cantaloupe looking shape around the red circle is the uterus. You probably need to full screen the video to be able to see anything.
I came home and slept most of the day. My doctor doesn't believe in bed rest, so I wasn't restricted, but it took a long time for the Valium to wear off. I was still pretty out of it the next day. We stayed with my folks and spent a nice day with them just relaxing. We came home last night. By the evening, I was feeling "twinges" in my abdomen. Today, it had progressed to cramping and pressure, in addition to twinges. Those could be really good signs (this is about when the baby would implant if he or she is going to and those could be signs of that), or they could mean nothing. It's hard not to over analyze everything. Honestly, had I not just had a transfer, I probably wouldn't have even noticed these symptoms. But they were mildly uncomfortable so I just took it easy today, napping, and keeping my feet up (perfect, since my Packers football game was on anyway), and doing chores as I felt ok and then resting again when I got sore again.
My beta is not for a while yet, so all we can do right now is wait. I still feel very much at peace, and with some hope. We'll see how soon before I break down and start testing on a home test. Right now I don't even own any because I never made it to the dollar store in my errands last week, and that's probably a good thing.
That's all the news that's fit to print (and then some). Have a GREAT week!