III. Models of human development Pluripotent stem cells (PSCs: ESCs and iPSCs) create opportunities to address the ethical and technical constraints associated with the use of human embryos. In order to discuss and evaluate these opportunities it is important first to provide a context for this work and look at its roots and assess its limitations. These days one has the impression that Embryonic Stem Cells (ESCs) are collections of genes, of epigenetic modifications all revealed by barcodes and sophisticated genomic technologies but, actually they are cells and their surname is embryonic, and cells are the units of the embryo, […]Continue reading
II. The 14-day rule and its implications The 14-day rule is an important landmark in the study of the development of human embryos. Established as part of the conclusions of the Warnock committee of Inquiry into Human Fertilisation and Embryology (1), later enshrined into British law by an act of Parliament in 1990, it demarcates a line that cannot be crossed when growing human embryos ex vivo and has served as the reference for work with human embryos since. At the time, 1984, the ability to culture fertilized human eggs ex vivo did not go beyond three or four days, […]Continue reading
I. What we know and what it can tell us about ourselves Embryos are, or should be, familiar entities to people reading this blog, most likely biologists or scientists with an interest in Biology; but don’t take this knowledge for granted. Ask around what is an embryo and you will find difficulty in expressing an answer: a baby, a foetus, something small inside the womb of a pregnant woman, something to do with In Vitro Fertilization (IVF) are some answers I encountered when doing the exercise. “Embryo” is a word behind an entity which remains a big unknown. In the […]Continue reading
What is a gastruloid?
A gastruloid is a three-dimensional structure made up of Embryonic Stem Cells (ESCs), that models certain features of early embryo development. In particular, gastruloids transition from an initial rounded to an elongated shape (a transformation similar to the early shape changes of the developing embryo), and generate cells associated with the three primary cell layers of early embryos (the germ layers) that are necessary for development of the different tissues and organs. Over time, these cells become organized with reference to a coordinate system, much as they do in the embryo. Gastruloids do not contain any brain cells or the cells necessary for the embryo to interact with the maternal environment.
Over the last year a trend has emerged, highlighted by several articles, to defend model systems, specifically in Developmental Biology. The reason for this is a perceived (and real) threat in the funding of research in yeast, C. elegans, Drosophila, sea urchins and other systems e.g ascidians or arabidopsis (the issue of the animalcentric view of developmental biology is an interesting one) despite their research potential supported by many and obvious substantial contributions to our understanding of biological systems. One of the latest in this series of statement was published recently (1: https://dmm.biologists.org/content/10/12/1381). The authors do an excellent exposition of […]Continue reading
Disclaimer: I am not a historian of Science and these views are, simply, sketches from the fringes of my interest in the subject as a practitioner of Developmental Biology. Sometimes it is possible to draw some sort of a straight line in the history of Science. For example, one can build a sensible narrative across an axis Galileo-Copernicus-Kepler-Newton….or, sort of, as most of the time a scientific discipline is a pidgin of varying questions, thought traditions, data and, importantly, visions of different scientists and surprising experimental results. Any attempts to trace a scientific discipline to a specific root will be […]Continue reading
COI: our group has an interest in these matters and the post reflects this and contains references to our work. The idea of making a human being from natural or unnatural parts has been more than a curiosity for centuries. The story is told in a little known book by Philip Ball (â€œUnnatural: the heretic act of making peopleâ€ Vintage books, London 2012) and has many a fascinating angle, though the bit I really enjoy is the development of in vitro fertilization by Patrick Steptoe and Robert Edwards. So much Biology behind what today is a routine clinical procedure! This […]Continue reading
Once upon timeâ€¦.somebody said that Genetics is Ariadneâ€™s thread of Biology, the only way to guide us out of the labyrinth that is a biological problem. Nowhere has this been more true than in the analysis of development, the processes underlying the emergence of an organism. In this spirit, it is the systematic application of genetic analysis to Drosophila melanogaster and Caenorhabditis elegans spearheaded a deluge of information that started modern â€˜Developmental Biologyâ€™ (the study of the dynamics of pattern and form in embryos, as opposed to â€˜Embryologyâ€™, the detailed description of the different stages associated with embryos). The success […]Continue reading
A meeting was held recently at the Pasteur Institute on the topic â€œEngineering the embryo: beyond Systems Biologyâ€. The event brought to my mind a question I pose to the final year undergraduate class: how should we approach a biological problem? like physicists or like engineers? The relationship between Physics and Biology has a long and very distinguished history, strewn with technical contributions that have often changed the direction and pace of biological research. Microscopy and X-ray crystallography would not have happened without the intervention of the physicists. To see this you donâ€™t need to go further than the 2014 […]Continue reading
A catalogue is not a map and if you want to transform a catalogue into a map, you probably need to understand what the map is for. The launch of the Human Cell Atlas Project (https://www.broadinstitute.org/research-highlights-human-cell-atlas) has caught the eyes and the ears of newspapers, the mind of some scientists and, obviously, the imagination of the leaders of the project. If you see the headlines, it might tempt you. After all, the prospect and challenge of learning the secrets of 35 trillion cells (3.5 x 10^12) is an impressive undertaking. The number reminds us of Avogadroâ€™s number and, of course, […]Continue reading