Urea, also known as carbamide is an organic compound that contains has the formula CO(NH2)2, this compound has two NH2 groups which are joined by a carbonyl C=O group. Urea serves an important role in the Metabolism (Good old Urea Cycle) of nitrogen containing compounds by animals, and is the main nitrogen containing substance in the urine of mammals.
In the case of the images below, I obtained a 1940's era microscope slide which was of Urea crystals. These were imaged by dark field microscopy and the respective images are shown below.
To capture these images, which were at 4x and 10x magnifications I needed to use my focus stacking setup. This consists of the below equipment;