Abstract
Astrocytes are the largest population of glial cells in the central nervous system (CNS). Their participations in several functions of the central nervous system and their contacts with the neuronal elements give these cells very important roles to play in the development; they participate in a variety of vital and pathological functions. In addition to the structural support, they play roles in the metabolism, production and release of several molecules, replacement and maintenance of neurons and the immune function. The similarity between humans and sheep in several developmental and anatomical aspects give to sheep the importance to make it an excellent animal model for studying astrocytes in many vital and pathological processes. The aim of this paper is to present the development and functions of astrocytes and their interventions in the pathology of the CNS in humans and in sheep. Finally, the use of sheep as an animal model to astrocytes in experimental studies is discussed.