ABSTRACT
In this chapter, we review the morphological studies of ACE2, including its localization in tissues, and related findings. Angiotensin-converting enzyme 2 (ACE2) is a zinc metalloproteinase and transmembrane glycoprotein distributed across the plasma membrane and serves as an important regulator of the renin–angiotensin system (RAS), an important player in balancing homeostasis in the body. It is an important regulator of the RAS and plays an important role in maintaining homeostatic balance in the body. However, the recent global epidemics of SARS-CoV and SARS-CoV-2 coronaviruses and the enormous amount of research on the response to COVID-19 have revealed that the viruses not only "anchor” the host cells during membrane fusion, but also induce ACE2 receptor signaling to maintain homeostasis. The ACE2 protein is expressed in a wide variety of organs in the body, but in this study, we have demonstrated the localization of positive cells stained by ACE2 immunohistochemistry in liver, kidney, alveolar tissue, pancreas, colon, oral mucosa, and salivary gland. In this chapter, the localization of cells stained positive by ACE2 immunohistochemistry in liver, kidney, alveolar tissue, pancreas, colon, oral mucosa, and salivary gland is presented, and a review of the observations and disease associations reported to date is given. © 2023 Elsevier Inc. All rights reserved.