It’s pretty hard to imagine how the embryo, which starts out as a single cell, becomes a baby at all. It’s a wonder how through splitting up and dividing, it transforms into something way different from when it started out. It’s a bit of a microscopic miracle, frankly.
But that’s just the tip of the iceberg when exploring the wonders of embryos. It turns out that there's a bunch of stuff happening inside of you that is simply mind blowing.
If you want to get to know your microscopic little loved one, here are a few crazy things about them that will make you love them even more.
15 Why Twins Run in Some Families
We all know that twins run in some families. That is, if you have close relatives who are twins or are a twin yourself, your chances of having children or grandchildren who are twins are higher.
Scientists have wondered about this for a while, and recent studies have determined that it has something to do with the follicle-stimulating hormone or FSH. This hormone regulates egg production in your ovaries. It turns out that women who are predisposed to have higher levels of FSH or receptors in the ovaries that are more responsive to FSH, are more likely to release two or more eggs for fertilization at a time.
14 All Planned Out at Four Cells
Scientists have found that as early as two days, when the embryo is made up of a whopping four cells, each cell already knows what it’s going to be. In a study published in the Cell journal, researchers discovered that each of these four cells already begin to express their genetic code differently.
Essentially, each cell already has a plan as to which parts of the body it’s going to split up to. Not bad for a handful of microscopic stuff.
13 Squishy Embryos are the Best
Strangely enough, studies on in vitro fertilization have found that embryos that are, we kid you not, squishy, are the best ones for implantation. Basically, researchers use a pipette to give the single-celled embryo a little squeeze right after fertilization. Squishy embryos were 50% more likely to result in term birth than those determined viable through old methods.
12 Embryos can be Frozen for Later Use
When you cook too much food, you can put it right in the freezer to use later. It turns out you can do just the same with embryos. Scientists from Australia and New Zealand have been doing just this and have now achieved success rates similar to the implant of fresh embryos.
Nice to know if you’d like to make a baby, but want to hold off pregnancy for a while!
11 They Have to Pass a Test
In order to implant into the lining of the uterus, an embryo has to pass a simple test. They have to prove that they can produce enough trypsin, an enzyme that tells the womb to get ready for the incoming baby.
Typically, embryos with genetic abnormalities fail to pass this test. However, if the womb is less responsive to trypsin than usual, it may be harder for the embryo to implant.
10 Mother’s Mood and Baby Brain
Many mothers say that the baby in their womb is somehow able to feel their emotions. Studies show that this could be true. Anxiety and stress during pregnancy has been found to increase the likelihood of giving birth to babies with mood and behavioral problems.
Scientists think that this may be because the stress hormone cortisol crosses the placental blood barrier and can affect embryonic brain development. Just another reason to keep pregnant women free from stress!
9 Most Embryos Don’t Make It
Most pregnancies do end up in miscarriage. However, in most of these cases, the mother won’t even know that she’s pregnant. Embryos with genetic abnormalities are likely to fail to implant in the uterus, resulting in an invisible miscarriage. Usually, these occur before the woman has her period and so the next period comes at about the right time.
Other times, she will have scanty bleeding if the embryo manages to implant. If miscarriage happens, however, she will have her regular period as usual. Other factors that contribute to miscarriages are health problems, smoking, drug use and just a general failure to implant.
8 Embryonic Food Preferences
The types of food that a child will enjoy seems to be directly related to what their mother ate early in pregnancy. This is because the nutrients resulting from mother’s digestion reach the developing embryo through the placenta. As the embryo is constantly exposed to these nutrients, it unconsciously develops a preference for these that can be carried on even when they’re out of the womb.
One study, for instance, found that mothers who had eaten plenty of salty food to calm hyperemesis gravida gave birth to babies who preferred super salty foods themselves. This is another reason why you need to eat veggies when you’re expecting!
7 Embryos Can Tell Left From Right
Early in its development, an embryo pretty much already knows which side will be right and which will be left. This has puzzled scientists for years, but recently they’ve discovered that cilia, or little hairs on the embryo, help determine which is which.
It turns out that cilia make clockwise sweeping motions, which plays a role in how embryonic cells distinguish the which parts of the body are in the left side or the right side. If the cilia make a counterclockwise motion, this results in a person with a rare condition called situs inversus. This affects 1 in 10,000 persons and means that all the organs in the body are inverted left-to-right.
Generally, there are little risks for a person with situs inversus. However, it can pose a problem when they’re coming in for treatment and the doctor looks for things in the wrong places! It can be alarming at first, but once the condition is discovered, health practitioners adjust to the expected differences in organ placement.
6 Female Embryos Split Faster than Males
In a 2014 study, researchers studied the differences in embryonic development between males and females. The study found that female embryos tended to show earlier cavitation than their male counterparts. The difference was quite tiny, though, so researchers still aren’t sure if this has a significant role in the development of embryonic sex organs.
5 Embryonic Cells Dance
Scientists have found that embryonic cells do a rhythmic dance around each other early in development. This is pretty much regulated by the same mechanism that allows our muscle cells to contract. When viewed microscopically, scientists say that it looks like a wave that travels around the cells at regular intervals. You can imagine this as a bunch of dancers in a circle doing one big, arm wave.
This dance occurs when the embryo has about eight cells and is getting ready for a process known as compaction. Compaction bonds the cells together into one organism when it previously was a separate group of loosely attached cells.
4 Some Embryonic Cells Stop Growing
Senescence is a property of body cells to stop proliferating in response to stress. Previously, this process was often linked to aging and cancer. Interestingly, it was seen in embryonic cells by a research team in Spain.
It turns out that programmed “stopping” of certain cells helps control the development of some organ systems, such as the nervous system. The research team also found that macrophages regularly remove some of these senescent cells in the development process. Scientists are interested in this research because senescent cells seem to be found primarily in systems where congenital defects are common.
3 The Embryo Graduates at 8 Weeks
At around 8 weeks, the embryo “graduates” into a fetus. Basically, an embryo is when your baby is still differentiating the cells that will turn into all the different body parts. By the end of it, your baby looks like a tiny, rough baby shaped in clay. Once it’s a fetus, your baby’s main job is to grow all those parts until they’re ready to function for the outside world.
2 Heart First
The first functioning organ in an embryo is the heart, which develops at about 4 weeks. Around this time, the embryo is too big to live off nutrients diffused from the placenta. It now needs its own pumping mechanism to deliver nutrients to all its cells, which are growing farther from the implant point on the placenta.
It starts off as two little endocardial tubes that eventually fuse to form a single heart tube with a left and a right portion. As the tubes begin to fuse, the heart tube begins pumping. This then folds into itself, eventually forming the atria and the ventricles.
1 First Heartbeats
When the heart tube begins to beat, it often starts off at a rate that syncs with your own heartbeat. The heart then begins to develop its own pacemaker, or the cells that produce the electrical signal that triggers the synchronized lub-dub of the atria and ventricles. Once this pacemaker is in control of heartbeat, it begins to pulse at twice the rate of your heartbeat.
You won’t be able to see the heart beating through ultrasound until about 8 weeks, though. By the time you get to get to hear the heartbeat through Doppler, it will still be beating pretty fast. Don’t be alarmed by this. A fetal heartbeat, and even a baby’s heartbeat naturally beats at a fast rate, but slows down to the adult rate over the course of childhood.