With the word ‘developmental’ in the title, as you can imagine, there are lectures about embryology as part of the course. As the aim of the lab section is to support and extend what is taught within the lectures we naturally include an embryology class too. During the three hour session each student constructs a three dimensional model of a human four week old embryo (“today we’re making babies!”). Details are given here on the Auckland Uni website and the instructions are copyright to Colin Quilter 2003.
Each embryo is made of modelling clay called Du Kit and are baked before being returned to the students, giving everyone something to take home and keep. Teaching the class is a lot easier when you’ve been through it before so all demonstrators and tutors are given a modelling clay kit and the instructions then sent home to have a go. Here is the clay sitting on my dining room table ready for me to start.
The clay comes in different colours so that each germ layer or type of blood vessel can be colour coded. Normally we’d use dissecting instruments to help with the modelling but I don’t have a dissection kit at home so I raided the kitchen drawers.
The first section to make, and one of the hardest, was the neural tube. It takes a bit of playing for the clay to warm up and also I was still getting the hang of how to work it at this point. The instructions are to scale at this point so the best method is to lay the clay on the page to see if it matches, but it’s easy to make the embryo flat on one side while doing this whereas an embryo should, of course, be rounded and somewhat smooth.
Then the notocord and gut sections are attached, giving the main internal structure of the model. It’s kind of cool how putting on the auditory and optic vesicles make it look more like a human.
At this point I discovered that my home has a hazard we don’t usually face in the lab:
After shutting the cat out of the room I started putting on blood vessels. The colour coding really helps here, purple for mixed blood, red for oxygenated and blue for deoxygenated. The next picture has the aortic arches and other arteries attached.
Since the embryo is getting oxygen from the mother rather than the lungs the blood flow is different to what I’m used to having studied mainly adult physiology. I found this all a bit confusing at first but being able to trace the different vessels with their colour coding to and from the heart to the various other places they go really helped clarify what was happening. I would never have figured this out so well from just pictures, there’s something about physically laying the tubes down in the right place that sticks it into my brain.
Then I just needed to add somites along the back and the mesonephros and trigeminal ganglion. An actual embryo will have 43 somite pairs but we accepted any number as long as they were correctly paired and positioned and the sizes were appropriate. Mine has 14 pairs.
So there’s the end product, a beautiful four week old embryo. There are a few tissue types missing from this model to make it easier to see what’s going on, so it’s not technically a complete embryo. However after looking at the marking schedule and checking everything over I think I’ve done a good job, I’d give myself ten out of ten for this effort.
The students on the whole do seem to enjoy this lab, particularly when they get the finished product back at the end. And I was actually surprised at how much I learnt about how everything fits together and what turns into what after both making my version and teaching it to the students, so I think it’s an effective method for teaching this stage of human development.