Taking a Side

What am I looking at?

This image shows a 1-millimeter-thick slice through the brain of a mouse, with neurons expressing a gene that codes for an enzyme called kallikrein-related peptidase 8 labeled in orange. You can see random and asymmetrical clumps of these cells (1 and 2), suggesting that this gene is expressed randomly throughout certain parts of the brain during development.

Click on the right arrow to see some additional images of different brain areas that display the same phenomenon.

Biology in the background

The brain has two hemispheres, or sides. During development, the two hemispheres develop at roughly the same rate and in roughly the same order.

This means that during development, many genes become active at about the same time on both sides of the brain. However, there are some genes that do not express evenly across the brain during development, turning on in a seemingly random order and at different locations in the two hemispheres.

These images represent one of the genes that expresses randomly and asymmetrically during development. This pattern of gene expression can give researchers important information about the gene’s role during development and even in adulthood.

The enzyme that this gene codes for is very small, about 15 nanometers across, or roughly 5,000 times smaller than the width of a human hair.

Technique

These images were created using confocal microscopy.