The Veterinary Microscopic Anatomy Review series is a 21 volume set of interactive books to allow a Q&A type review of microscopic anatomy structure and function. The histological sections are taken from multiple domestic species, including the canine, feline, bovine and equine. In this first unit of the series, the structures within the cells will be identified based on their H&E staining characteristics. We will also examine apical surface modifications of cells. Identification of these structures is foundational to knowing the function of cells, tissues and, ultimately, organs. The stages of mitosis, as seen in tissue sections, are also covered in this unit.