Lecture 1 - First take an egg...
We need to know how the cells are assembled to make structures. ls it possible that everything is specified in the egg and that there is a 'homunculus', the animal present as a tiny form which just grows during development? How do sheets of cells get moulded into organs like our brain? Why do we pass through a stage in development when we look a bit like embryonic fish with gill slits?
The way an animal develops can be seen by looking at the sea urchin embryo. The egg divides to give a hollow sphere of about 1,000 cells. Then gastrulation begins - the rearrangement of the early embryo so that the main parts are moved to the right place, like the formation of the gut, which is formed by cells being pulled inwards to form a tube. The cells have micro-muscles which bring about the change in shape. Changes in the adhesion between the cells is also important. Our brains develop from a sheet of cells that folds up into a tube and uses similar mechanisms.
Some cells can migrate long distances to specific sites. How do they find their way? Some make use of chemotaxis - following a chemical gradient, and others explore the environment with long processes and move where they make the most stable contact.
Assembling involves a programme of cell activities like cellular contraction and change in adhesion. The analogy is paper-folding - Origami. A simple programme of instructions can generate very complex forms. This is the programme that Frankenstein needs. In evolution this programme is modified so that a bone from a reptile's lower jaw becomes part of our middle ear.
About the 1986 CHRISTMAS LECTURES
In the 1986 CHRISTMAS LECTURES, Professor Lewis Wolpert (1929-2021) explores developmental biology in a series titled 'Frankenstein's Quest'. Quoting the fictional Dr Frankenstein: "After days and nights of incredible labour and fatigue, I succeeded in discovering the cause of generation and life..." These lectures will look at how life really is generated.
All life comes from cells and all the animals we see about us come from just one cell, the fertilized egg. How does the egg give rise to bats and boys, gnats and girls, eyes and arms? The egg divides and gives rise to many cells which move, multiply, change, and communicate, and from these activities animals emerge through embryonic development. Like an imaginary Frankenstein, we will explore what we need to know in order to control development in order to create not a monster, but an angel.