tailieunhanh - DEVELOPMENTAL NEUROBIOLOGY - PART 2

Trong những năm gần đây, dân số tăng sinh này đã được nghiên cứu như là một ví dụ của tế bào thần kinh sau khi sinh và tế bào gốc proliferations. Phổ biến vũ khí trong khu vực subhilar của vùng dentate gyrus đã được chứng minh là bị ảnh hưởng bởi di truyền khác biệ | Cell Proliferation in the Developing Mammalian Brain Chapter 2 35 some portion of which survive migrate into the granule cell layer form connections and become a permanent part of the dentate gyrus granule cell layer Bayer 1982 Bayer et al. 1982 Crespo et al. 1986 Stanfield and Trice 1988 and exhibit important functional properties van Praag et al. 2002 . Importantly it has been shown that during the adult period the number of granule cells increases Bayer 1982 Bayer et al. 1982 the newly produced granule cells displace earlier generated granule cells Crespo et al. 1986 and they grow an axon into the molecular layer of CA3 Stanfield and Trice 1988 . In recent years this proliferative population has been studied as an example of postnatal neurogenesis and stem cell proliferations. Proliferation in the subhilar region of the dentate gyrus has been shown to be affected by genetic differences Kempermann et al. 1997 Hayes and Nowakowski 2002 species differences Kornack and Rakic 1999 various treatments such as drugs Eisch et al. 2000 stress Tanapat et al. 1998 Gould and Tanapat 1999 behavioral experiences Kempermann et al. 1998a hormones Cameron et al. 1998 Tanapat et al. 1999 aging Kempermann et al. 1998b and exercise van Praag et al. 1999 . Although proliferation in the dentate gyrus persists throughout the life span of the animal there is a significant decline with age Kuhn et al. 1996 Kempermann et al. 1998b in mice at 18 months of age the reported number of BUdR labeled cells observed after 12 daily injections is only about 25 of the number observed after a similar labeling paradigm at 6 months of age Kempermann et al. 1998b . This decline could be due to a decrease in the number of proliferating cells an increase in the amount of cell death in either the proliferating population or the output population during the 12-day period during which the BUdR injections were given or both. However as yet untested is the possibility that the difference could be a result of .