الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
Neurogenesis was firstly defined as the formation of the nervous tissue (neurons, oligodendrocytes and astrocytes); it is active in the pre-natal stages only. Later, it was found that some species can undergo regeneration of their nervous tissue even after birth. This splited the expression of ―neurogenesis‖ into two subterms: embryonic neurogenesis and adult neurogenesis.
At present, neurogenesis is used to define the formation of new neurons while gliogenesis is the formation of glial cells.
Until recently, it was commonly believed that the adult brain does not produce new neurons. During the last decades, a lot of studies came out with the idea that the adult mammalian brain contains some neural stem cells, which means that the adult brain may undergo adult neurogenesis so researches continued and experiments were performed to investigate the specific area(s) in the central nervous system which are related to adult neurogenesis. It was found that there are three main areas involved in adult neurogenesis of mammalian brains.
The first one is the subventricular zone (SVZ) (Luskin et al., 1993;Lois & Alvarez-Buylla, 1994). The second one is the subgranular zone (SGZ) of the dentate gyrus of the hippocampus (Altman & Das, 1965;Cameron et al., 1993;Kuhn et al., 1996;Palmer et al., 1997;Seaberg & van der Kooy, 2002;Aberg et al. 2003), and the most recently discovered; the Area Postrema (AP) of the dorsal vagal complex (DVC) in the brain stem (Charrier et al., 2006) . These mentioned studies proved that these areas are capable of adult neurogenesis in the mammalian brain.
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Early History of Animal Modeling
The use of animals as models in human anatomy and physiology began in ancient Greece (Table 1). These first recorded instances of comparative science were very observational, their purpose being to better understand human ontogeny and physiology. Fortunately, many of the findings of prominent thinkers like Aristotle were documented and conveyed to other countries via trade routes, and animal modeling soon became a research tool of both European and Arab physicians. While this early period saw great discoveries, there were still many misconceptions about the workings of the body, and it was not until the fourteenth through seventeenth centuries that animal modeling contributed to a true paradigm shift in our understanding of human physiology.
In the mid-sixteenth century, few physicians such as Servetus and Lusitano found that blood followed two connected but distinct circuits through the body, i.e. pulmonary and systemic circulation. In the late sixteenth and early seventeenth centuries, William Harvey studied and compared the anatomic and functional properties of the heart and vasculature in multiple species including eels and other fish, chicks, and pigeons. Based on these investigations, he penned several semina.