“Fake embryos” or “natural” embryos?
Let the “real” embryo stand up.
April 9. 2026
Jaap van der Wal, MD PhD, anatomist-embryologist en fenomenologist
Approximately 2,700 words – Reading time: 11 to 14 minutes
Introduction (applied to the situation of legislation in the Netherlands – can be skipped if necessary
Coming soon [1]The House of Representatives is set to deliberate on potential amendments and changes to the Embryo Act. Among other things, the discussion will focus on the status of so-called “artificial embryos.” These are human embryos that have been able to be created in the lab for several years now and are used for scientific embryological research. On December 16, 2025, the House of Representatives passed a bill (private member’s bill—Paternotte and Bevers) lifting the previously existing ban on using embryos created through “in vitro fertilization” (IVF) for scientific research. Now a second bill is pending, namely to amend the definition of an embryo so that so-called “synthetic” embryos or “artificial embryos” are also considered embryos. “A cell or a cohesive group of cells capable of developing into a human being.” The current bill defines anything that “reasonably” resembles an embryo as such; therefore, due to this change in definition, these “entities” from the lab will henceforth also be considered embryos under the law, just like “natural” embryos. These are embryos created from stem cells (techniques have also been developed that do not involve sperm or egg cells), sometimes referred to by some as “fake embryos.” The latter term was coined by Erik Vrij, an embryologist at Maastricht University, in the NPO TV documentary *Pregnant Thanks to Science* aired on February 24, 2026.
Fake or real.
The debate centers on whether it is scientifically correct and ethically justifiable to include both types of embryos under the Embryo Act. Another point of contention is whether such an equivalence could inadvertently open the door to the possibility of cloning humans, something that remains prohibited by law to this day. The experts working with these “fake embryos” seem to be caught in a dilemma. On the one hand, some argue that these embryos are “artificial” and “synthetic” and therefore should not be considered “natural” or “real”; on the other hand, it is argued that they behave just like “real” embryos. The latter argument would (if true!) make these embryos suitable for scientific research into early human embryonic development, which has so far been impossible for technical reasons (human embryos are no longer accessible for direct scientific research after implantation in the uterus). Will the members of the House of Representatives be knowledgeable enough to weigh these arguments for and against? What is at stake? If these artificial embryos are equated with real embryos, the 14-day limit [2] will also apply to these embryos. Might scientists wish to use these synthetic embryos to look beyond that timeframe? A difficult dilemma?
In professional circles, cautious, euphemistic (?) terms are often used for so-called fake embryos. They speak of “synthetic” embryos or “embryo models” and of embryoids and blastoids, which amounts to embryo-like or blastula-like [3]. Another commonly used term is Embryo-Like Structures (ELS). What, then, makes these embryos potentially “different” from “natural” embryos? Normally, both in vivo and under the conditions of in vitro fertilization (IVF), a zygote is formed. This is the very first single-cell stage of the human embryo, resulting from the (whether or not forced) fusion of two germ cells, a sperm cell and an egg cell. Germ cells are highly specialized sex cells. During fusion (conception), not only do the nuclei of the two germ cells come together—combining the half (halved) number of chromosomes (23) from both cells into the normal total of 46 chromosomes—but other cell organelles and substances are also present. Other cell organelles and substances are also involved, which, for example, enable the first division of the zygote and also alter the zygote’s DNA through so-called epigenetic factors into a different state of activity (“gene expression”)
These “ELS embryos” have a completely different mode of formation and are of a highly unnatural origin. So-called somatic cells, such as skin cells, are taken from a person and reprogrammed using biochemical tools into so-called stem cells. These are cells that have not yet been genetically specialized for a specific functional purpose and are often referred to as “omnipotent” (“in principle, anything is still possible”), and thus bear a certain resemblance to a zygote, but have an entirely different origin. A group of about 120 of these cells is brought together by placing them in specific funnel-shaped chambers (“shakers”). There, they tend to “grow together,” forming a cluster of cells. And that cluster of cells, in turn, resembles the previously mentioned morula stage. The morula is the multicellular embryo that develops from the single-celled zygote after a day or two or three, as the zygote undergoes a series of so-called cell divisions. Such a morula consists of eight cells, and after several divisions, as many as 64 cells, which are in principle still identical (genetically, at least) and can also be considered a form of stem cells. The artificially created cluster of cells (an ELS, in other words) then, when certain molecular substances are added, begins to differentiate into various types of cells and tissues. In the literature, this is sometimes referred to as a spontaneous process, but given the chemical manipulations required to make this happen, that term “spontaneous” should be taken with a grain of salt. Elsewhere, the term engineering is used, which more accurately describes what is taking place here. After some time, a stage even arises in which the embryo assumes the fundamental organization of an animal body, the so-called gastrula stage, with precursors of organs (gastruloids). This process can be guided and manipulated by the selective addition of certain epigenetic or morphogenetic substances. Some researchers are thus reconstructing the initial stages of brain and heart development, processes that normally occur around the 22nd day of human development. In mice, embryoids have already been cultured that develop a head-tail axis, a dorsal-ventral axis, and a left-right axis, with organs in a primitive stage and in the correct location. It is also already possible to inhibit the development of a part of the embryo, such as the aforementioned trophoblast, from which the placenta normally develops!
Some embryologists will, of course, view these kinds of developments as a tremendous leap forward. This is because it gives them the opportunity to study and experiment with early embryonic development—which normally eludes the researcher’s gaze (since it takes place in the “black box” of the uterus)—in the lab. Various articles describing these experiments also emphasize that these embryos cannot develop into a normal full-term pregnancy because they do not implant in a uterus (implantation). Normally, a blastula a few days old will implant in the uterine lining, at which point the embryo also begins to develop the placenta. Development up to birth then essentially takes place within that placenta, meaning through metabolic interaction with the mother’s body. Whether an artificial uterus could ever be developed and used in this context is currently (fortunately?) still a matter of science fiction. One might get the impression that the artificial and “fake” nature of these embryoids is being emphasized so as not to give the impression that the goal is to create artificial embryos that could develop into children outside the mother’s body, even though such practices do create the possibility of doing so.
There is something else that makes these “fake embryos” perhaps a revolution in the field of embryological research, but also constitutes an urgent argument for absolutely not considering these embryos to be normal or natural. Ultimately, these embryos do not arise from the union of a sperm cell and an egg cell but are, in fact, clones of a specific person. Thus, there are no parents, neither biologically nor genetically. In the aforementioned private member’s bill, embryos are also used for scientific research, but these are created using donated sperm and eggs. In the (as yet) theoretical case that the so-called “fake embryos” referred to here were allowed to develop into a full-term fetus or child, this would amount to the birth of a cloned human. To date, it is still generally accepted (from a political standpoint) that the birth of cloned humans must remain prohibited. The embryos created using the ELS technique and used solely for research are, in fact, already human clones. Although they have so far been “utilized” for scientific research, further development is, of course, quite conceivable, and then the birth of a human clone would be made possible [4] . The question, however, is whether we actually want to take the step toward creating cloned humans in this way.
The contradiction lies in the fact that such artificially created embryos are considered scientifically representative of normal embryonic development. In the extreme case, one would therefore have to demonstrate that such an embryo could indeed lead to a full-term pregnancy and result in a normal human being. This could thus lead to the creation of “fake children” (?). In addition, we must seriously ask ourselves who is responsible for these children. To whom do such children “belong”? Are they even legal entities? Ultimately, this could lead to a situation so ethically and morally twisted that it would be better not to get involved in the first plac
Back to the dilemma. On the one hand, people apparently like to point out that these are non-natural embryos (hence the term “fake embryos”), which allow us to observe the early stages of human development—which usually take place in the “black box” of the womb—in vitro. On the other hand, these “embryo models” are considered representative of “real” embryonic development. That’s having it both ways. After all, there is no evidence whatsoever that what applies to the fake embryos also applies to real embryos. In any case, there is an earnest search for arguments to demonstrate that fake embryos develop in exactly the same way as real embryos. In biology, the argument of homology is used in such cases. Homology means “resembling one another.” In the July 7, 2023, edition of De Volkskrant, the issue at hand is (perhaps unintentionally) put into exact words: “Major upheaval in science: never before have artificial human embryos resembled the original so closely.” And if they look alike, then they must be (almost) the same..
When I used to show medical students images of the early stages of human development, the discussion of homology would quickly come up. The fact that an early human embryo looks “animal-like” does not necessarily mean that it is an animal form. At the beginning of the last century, the resemblance between the human embryo and animal forms was seen as proof that human embryonic development was a kind of recapitulation of its evolutionary development. (For many people today, this is also the common argument for viewing humans as just another animal species.) However, this thesis based on homology does not hold up when one considers how different the formation of the two compared forms actually is. In evolution, there is a constant change in the genome of species (mutation), whereas this is not the case in embryonic development. The fact that two things look the same is not an argument that they are the same. But apparently not everyone is aware of this. For instance, in the debate over whether “embryo-like” entities and embryos are the same or equivalent, biologists today can be heard invoking the so-called duck test [5] . In that context, Gert Jan Veenstra, a molecular developmental biologist at Radboud University, argues as follows: “If it looks like a human embryo, has the genes of a human embryo, and functions like a human embryo, then it is most likely a human embryo.”
That is too simplistic and, in fact, quite unbiological. This is also related to the fact that the definition of an embryo, which is generally used, reads: “A cell or coherent group of cells with the capacity to develop into a human.” This description contains a bias based on (in my view) outdated reductionist biology. Developmental biology is about becoming, about processes, and not merely about forms or structure (“anatomy”). A zygote is not a cell, but a single-celled human organism—a “body,” in other words. In a more organicist conception of biology, an embryo is not something that will develop into a human—moreover, it is never clearly specified when it would be “ready” and thus no longer an embryo—but, like every living being, an appearance in time. An autopoietic being that shapes itself, organizes itself, and sustains itself throughout its life. And certainly not a machine-like thing, built from parts that can only function once it is complete. An organism is functional from the very beginning; the same cannot be said of a device or machine
So the duck test doesn’t apply so simply. Take the case of synthetic embryos presented as artificially formed “cell clusters” and thus supposedly resembling the 2- to 3-day-old morula stage of the human embryo. The human morula is all too often referred to as “a clump of cells,” often with the dismissive, reductionist undertone of “Oh, a human embryo is nothing more than a clump of cells.” Again, the frequently invoked “not-yet” principle of an embryo. How does that cluster of cells come about in the “real” and in the “fake embryo”? Do you have to bring them together with some sort of net? That is actually roughly how the creation of fake embryos works. You bring them together in a funnel filled with a specific liquid (called a shaker) and more or less force them to make contact with one another. How completely different it is in vivo with the morula. The zygote is a single-celled human, and this single-celled organism will subsequently divide as the number of cells increases. The morula is thus a multicellular human organism, a whole that has organized itself into multiple cells. It may resemble a clump of cells, but in fact it is not. In evolution, as biologists now assume with considerable certainty, there was once, in the distant past, a grouping of primitive single-celled organisms that subsequently, likely because it offered a survival advantage, began to form colonies. And so multicellular organisms arose from the clumping together of unicellular organisms: the whole is the result of the combination of the parts (the building-block principle). The multicellularity of a morula, however, arises in a completely different way, namely because a unicellular organism becomes a multicellular organism through cell division (the parts arise from the whole, so to speak). What do you mean by homology? Embryologists bring clumps of “stem cells” together in test tubes, literally assembling an embryo, which then, guided by “epigenetic” factors, begins to look and behave like a human embryo. And that would then be the same as a “normal” morula? Incidentally, no one knows yet whether this “development” can continue spontaneously in a test tube without intensive metabolic contact with a maternal organism. How would you prove that? By trying to let them grow? In an artificial womb or something? And would they then become “fake children” and “fake people”?
When creating artificial embryos from stem cells, the cells are brought together by combining them in a culture medium containing a specific cocktail of proteins and growth factors, which stimulate the stem cells to divide and self-organize into a spherical structure resembling an early embryo. Scientists add a “carefully formulated cocktail of proteins” that stimulates the stem cells to divide and develop. This is described as: “the aggregated stem cells are prompted to communicate and self-organize.”
In all of this, it must also be emphasized that the entire process involves cloning—genetic copies of existing human individuals. Reproductive cloning of animals is already widely practiced, but it involves a great deal of “collateral damage” in the sense that many of the cloned animals exhibit genetic and other abnormalities or are sometimes not even viable at all. Only a small percentage of cloned embryos develop normally. In my opinion, we should be rational and sensible and leave the discussion about homology where it is. In any case, there is sufficient justification not to regard these so-called “fake embryos” as normal embryos and not to tolerate any research that would attempt to prove otherwise. And above all, not to categorize them as equal—and thus potentially equivalent—by virtue of a law.
The bill currently before us is based on the hoped-for similarity between synthetic ‘embryos’ and real embryos. But the difference between synthetic ‘embryos’ and real embryos is more important than the similarity. This difference is erased by the bill under consideration, whereas it should actually be strictly maintained. This can only be properly regulated in a new law, separate from the Embryo Act. An amendment to the Embryo Act in the direction currently proposed effectively obscures human cloning and crosses boundaries by equating what is not equal.
[1] Scheduled for April 15, 2026, at the time of writing
[2] In the Netherlands, as in many countries, the limit up to which embryos may be experimentally cultured and studied is set at 14 days after conception. This timeframe has not been altered in the aforementioned legislative amendment either.
[3] Blastula is the term for a human embryo a few days old that looks like a sac containing an eccentrically located cluster of cells, called the embryoblast or inner cell mass, which is often referred to as the “actual embryo.” The wall of the sac, the trophoblast or outer cell mass, develops into the placenta.
[4] A misconception (raised by a state secretary) is that human cloning only occurs when a child is born from a cloned embryo. Biologically speaking, any organism that is genetically identical to another organism is a clone. The stage of development and whether or not it has been born are irrelevant. According to the state secretary, the “fake embryos” should therefore be considered “not-yet-clones.” This makes the definition of “real or not” very vague.
[5] Wikipedia: The duck test: If it looks like a duck, swims like a duck, and quacks like a duck, then it probably is a duck. The poet James Whitcomb Riley (1849–1916) is said to have coined this “rule.”