人类早期发育为胚胎和成年生活奠定了基础，但仍难以研究。通过干细胞能够组织成类似于囊胚的结构，我们称之为“囊胚体”，解决方案应运而生。这种胚胎模型可以无限制地提供，因此可以支持科学和医学进步。然而，它的预测能力取决于它是否忠实地重现了囊胚。在这里，我们描述了如何形成人类囊胚体，(1)高效地实现囊胚的形态，(2)根据囊胚发育的节奏和顺序形成分化线索，(3)最终形成反映囊胚（植入前期阶段）的转录细胞群。我们使用了三种不同的商用96孔和24孔微孔板，并展示了类似于我们自制的结果，表明在临床体外受精培养基中形成囊胚并可冷冻运输。最后，我们解释了如何重现植入进入内膜器官样体的定向过程，特别是在这些组织受到激素刺激的情况下。人类囊胚体需要4天形成，需要10天准备内膜植入测试，我们已将囊胚培养至6天（相当于13天），根据我们的经验，我们预计有1年人类多能干细胞和器官样体培养经验的人应该可以执行该协议。总之，囊胚体为早期妊娠的科学和生物医学发现计划提供了机会，并提供了使用胚胎的伦理替代方案。© 2023.Springer Nature Limited。

Human early development sets the stage for embryonic and adult life but remains difficult to investigate. A solution came from the ability of stem cells to organize into structures resembling preimplantation embryos-blastocysts-that we termed blastoids. This embryo model is available in unlimited numbers and could thus support scientific and medical advances. However, its predictive power depends on how faithfully it recapitulates the blastocyst. Here, we describe how we formed human blastoids that (1) efficiently achieve the morphology of the blastocyst and (2) form lineages according to the pace and sequence of blastocyst development, (3) ultimately forming cells that transcriptionally reflect the blastocyst (preimplantation stage). We employ three different commercially available 96- and 24-well microwell plates with results similar to our custom-made ones, and show that blastoids form in clinical in vitro fertilization medium and can be cryopreserved for shipping. Finally, we explain how blastoids replicate the directional process of implantation into endometrial organoids, specifically when these are hormonally stimulated. It takes 4 d for human blastoids to form and 10 d to prepare the endometrial implantation assay, and we have cultured blastoids up to 6 d (time-equivalent of day 13). On the basis of our experience, we anticipate that a person with ~1 year of human pluripotent stem cell culture experience and of organoid culture should be able to perform the protocol. Altogether, blastoids offer an opportunity to establish scientific and biomedical discovery programs for early pregnancy, and an ethical alternative to the use of embryos.© 2023. Springer Nature Limited.