Recently, research scientists from Israel had a notable achievement. They successfully created a lab-grown human embryo model using stem cells and chemicals, without the need for an egg or sperm. This development has provided a new light on the early stages of embryo development.
Methodology: The Birth of the Embryo Model
The Israeli researchers utilised stem cells and chemicals to construct a model representing a 14-day-old human embryo. Key to this creation process was the combination of stem cells and chemicals which served as the starting point in producing an embryo-like structure. This structure managed to spontaneously assemble into various types of cells which lead to the formation of the fetus, facilitate nutrients provision to the fetus and establish structures like placenta and umbilical cord to support the fetus. Despite the success, one challenge faced was that only 1% of the mix autonomously assembled indicating a need for improved efficiency.
New Insights: Discoveries from the Embryo Models
These models have been beneficial in uncovering errors related to DNA duplication and chromosome distribution. Researchers discovered that abnormalities in DNA duplication arise early during the developmental stages, which adversely affect cell division. Furthermore, these models offer an opportunity to study gene functions and their influence in fetal development.
Significance: Importance of Embryo Models and Research
The study of early embryo development becomes ethically challenging post-implantation in the uterus. However, conducting research at these initial stages is crucial as most miscarriages and birth defects occur during this period. Understanding the normal progression of embryo development and the role of genetic factors can significantly enhance in vitro fertilization outcomes, enabling researchers to better understand the impact of genetic, epigenetic, and environmental influences on embryonic development.
Limitations: Usage of Lab-Grown Embryos
Contrary to what some may perceive, these embryo models are not designed for pregnancy. Their sole purpose is to study early fetal development. As a rule, they are destroyed after 14 days, and their implantation is strictly forbidden.
Ethical Considerations: Respecting the 14-day Limit
The ethical considerations surrounding embryo usage shift as the embryos transition from being mere cell clusters to becoming individuals. Based on regulations proposed in the UK in 1979, the embryos are generally destroyed after the 14-day mark, which coincides with the end of natural embryo implantation. This is also the stage when cells start forming an individual, and splitting into a twin becomes impossible.
Beyond Cells: The Primitive Streak and Individual Formation
The transition from an embryo being a cluster of cells to becoming an individual is usually marked by the appearance of the Primitive Streak – a linear structure in the embryo. This structure is a clear indication of the shift from radial symmetry (similar to an egg) to bilateral symmetry (characteristic of human bodies with left and right hands and legs).
Understanding Human Embryo and Stem Cells
A human embryo is a developing human right from fertilization until the end of the eighth week of gestation. It undergoes three main developmental stages – the pre-implantation stage, the implantation stage, and the organogenesis stage. The embryo, normally created by the fertilization of a human egg by a human sperm either in the female reproductive tract or in the lab, is composed of various types of cells that differentiate into numerous tissues and organs.
On the other hand, stem cells are unique cells with the ability to develop into specialized cell types in the body. They may be used in the future to replace cells and tissues that have been damaged or lost due to disease. Stem cells have two defining properties: their ability to endlessly divide to produce new cells, and their potential to transform into other types of cells that make up the human body.
Types of Stem Cells and Their Potential
The types of stem cells and their potential varies based on their source and their stage of development. Embryonic totipotent stem cells found in very early stages of a fertilized embryo can develop into any cell in the body and even form the placenta. Embryonic pluripotent stem cells derived from slightly more developed embryos can become many different cell types but cannot form the placenta. Adult multipotent stem cells found in various tissues in the human body are more specialized and can differentiate into a limited range of cell types specific to the tissue they are found in.