Final answer:
The leukocyte with a large, kidney-shaped nucleus and 'frosted glass' cytoplasm is known as a monocyte.
Step-by-step explanation:
The type of leukocyte that is characterized by a large, kidney-shaped nucleus with a 'frosted glass' cytoplasm is the monocyte. Monocytes are a type of agranular leukocytes, meaning they have smaller, less-visible granules in their cytoplasm compared to granular leukocytes. They exhibit a simple nucleus shape, which can sometimes have an indentation, but does not have distinct lobes.
Unlike lymphocytes, which also have large nuclei that absorb Wright stain and appear dark colored under the microscope and are much smaller cells with very little cytoplasm, monocytes are large, phagocytic cells that can engulf foreign particles and pathogens. They are distinguished from other leukocytes like neutrophils, eosinophils, and basophils by their cytoplasmic appearance and nuclear shape. While the granules in neutrophils typically appear light lilac due to neutral staining, the distinct feature of a monocyte is its unique nucleus and the frosted glass appearance of its cytoplasm. It is an agranular leukocyte with a simplistic nucleus shape, distinguishing it from other leukocytes like lymphocytes, neutrophils, eosinophils, and basophils.