The first few moments of a worm's life are a difficult time. Egg and sperm, which come together to create a new worm baby, are very different cells and their DNA is packaged up in distinctive ways. And the challenge is unpacking it and organising it all so that development can get started. This biological packaging material – proteins called histones – comes in various varieties, and special versions are put onto the DNA in eggs and sperm when they're made. Here we see the developing sperm inside a male worm, stained with fluorescent dyes that pick out different histones. Immature sperm are tightly packed together and stained pink due to one type of histone, but this is replaced with the green-stained version as they mature. These special histones could play an important role in shaping development, carrying extra information from mum and dad to the embryo.
Written by Kat Arney
BPoD stands for Biomedical Picture of the Day. Managed by the MRC London Institute of Medical Sciences the website aims to engage everyone, young and old, in the wonders of biomedicine. Images are kindly provided for inclusion on this website through the generosity of scientists across the globe.