OVAL cells seen in stem cells of -
Stem cells are located in sites called niches. These include:

Epidermal stem cells located in the bulge area of the hair follicle serve as stem cells for the hair follicle and the epidermis.
Intestinal stem cells are located at the base of a colon crypt, above Paneth cells.
Liver stem cells (commonly known as OVAL cells) are located in the canals of Hering, structures that connect bile ductules with parenchymal hepatocytes.
Corneal stem cells are located in the limbus region, between the conjunctiva and the cornea
The bone marrow contains hematopoietic stem cells as well as stromal cells capable of differentiation into various lineages.
Liver
Skin
Cornea
Bone