# Summary: Lab-Grown Model of Human Embryo
## Introduction
Due to ethical constraints and technical limitations, the study of human post-implantation development has been restricted. Until recently, the most comprehensive models were derived from mouse embryonic stem cells. However, a groundbreaking study published in the journal Nature has successfully used genetically unmodified human embryonic stem cells to create a "complete" model of a human embryo, revealing key insights into early human development.
## Key Findings
### Use of Human Embryonic Stem Cells
Previously, research was confined to mouse naïve embryonic stem cells to understand intrauterine development after implantation. For the first time, scientists have extended these findings to humans by utilizing genetically unmodified human naïve embryonic stem cells.
#### Example:
The researchers were able to replicate the three primary founding tissue types of the body—epiblast, hypoblast, and extraembryonic mesoderm—providing an avenue for deeper exploration of human biology.
### Complete Model from Implantation to 14 Days
Scientists from the Weizmann Institute of Science in Israel developed a "complete" model of a human embryo, starting from the implantation stage to 14 days after fertilization. This model represents the 3D structure and all known features of post-implantation human embryos at around two weeks old.
#### Example:
This model is so accurate that it even secreted a hormone that resulted in a positive commercial pregnancy test.
### Stem Cell-Based Embryo-Like Structures (SEMs)
The lab-grown human embryos, also known as SEMs, were developed without the use of sperm, eggs, or a womb. This indicates a significant leap in our understanding of human reproduction and early development.
#### Example:
This advancement could provide crucial information for treating fertility issues, as well as a better understanding of embryonic development without the ethical concerns of using actual human embryos.
### Spatial Allocation and Self-Organization
The study notes that the cell lineages properly allocated into defined embryonic and extra-embryonic compartments even without fertilization or interaction with maternal tissues. This suggests a natural tendency towards self-organization in the development of human embryos.
#### Example:
This phenomenon could be pivotal for understanding developmental anomalies and why they occur, providing insights into conditions like ectopic pregnancies or miscarriages.
## Implications and Future Research
According to the researchers, this SEM platform opens the door for studying previously inaccessible aspects of early human development, including post-implantation and peri-gastrulation stages.
## Conclusion
The creation of a lab-grown model of a human embryo using genetically unmodified human naïve embryonic stem cells marks a landmark in biomedical research. This will not only facilitate the study of early human development but also potentially revolutionize our approach to reproductive health and developmental disorders.
