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Synaptogenesis in the simple or combined culture of developing rat cerebrum
$29 SYNAPTOGENESIS
IN THE SIMPLE OR COMBINED CULTURE OF DEVELOPING RAT CEREBRa!
TOSHIO SHIRAI I, KOICHIRO SASAKI I~ and SHIGEO A I Y A ~ 2 , 1 D e p a r t m e n t of Anatomy, Yamagata University School of Medicine, Yamagata 990-23, and 2Department of Anatomy, Nippon Dental College, Chiyoda-ku, Tokyo 102, Japan. Synaptic formation was studied in the explant of cerebrum, in which the neuronal architecture was maintained during cultivation, from the developing rat. Slices were dissected from the cerebrum, spinal cord and cerebellum of rat at 1 day after birth, and the cerebrum alone was placed on the collagen or the cerebrum in contact with the cerebrum, spinal cord or cerebellum. These simple and combined explants were cultivated in a CO 2 incubator for 3 weeks. By the first week many neurites were found to run in the simple explant and to connect between both combined explants: and these connections continued by third week. At day 21, the simple and combined cerebral explants were observed with the electron microscope. The several various types of axo-dendritic and axo-spinous synapses were almost observed in the simple and combined cerebral explants. A few compound types of axo-dendritic synapses were also found. But the distribution rate of these synapses was different in simple and combined explants. The synaptic formation in the combined explants was more increased than that in the simple explants. There were no differences of synaptic types and these distribution rate between three combined cultures. From these results it is suggested thst the increase of synaptogenesis in the combined cultures is involved with the in-put axons derived from neurons in other explants into cerebral explant.
THE TRANSDIFFERENTIATION CULTURE
OF ADRENAL CHROMAFFIN CELLS INTO NEURONAL CELLS IN
MASAHARU OGAWA *I, TOMOICHI ISHIKAWA .2 and HITOSHI OHTA .3, Department of Physiologyl, Dept. Anatany 2 and Dept. Neuropsychi. 3, Kochi Medical School, Nankoku, Kochi, 781-51. Cultured adrenal chromaffin cells differentiate into neuronal cells responding to the nerve growth factor (Unsicker et al. PNAS 75;3498 (1978)) and develop functional synapses among neuralized chrcmaffin cells (Ogawa et al. Nature 307, 66 (1984)). In this study we examined the ultrastructural changes accompanying the neural transdifferentiation of adrenal chromaffin cells in culture. Adrenal glands were removed from 8- to 10-day old rats, medullae were isolated from cortex and the cells were dispersed with enzyme treatment. After individual chromaffin cells settled onto the dish surface, fine unmyelinated processes grew out, responding to NGF. The growth of processes continued with time, and dense dendritic networks were formed after 2 weeks in culture. In early culture days, numerous chromaffin granules (up to 350 nm in diameter) were dispersed throughout the cytoplasm. With increased time in culture, the chromaffin granules decreased from the central area and localized the more peripheral area of the cytoplasm and extened processes. By 2 or more weeks, a number of ultrastructural changes were observed in the cell body; the content of heterochromatin decreased, and the over all density of the nucleus was reduced. Golgi complexes, mitochondria and especially rough endoplasmic reticula were considerably increased. Chromaffin granules progressively disappeared from cell bodies and processes, while dense core vesicles ( 6 0 ~ I 0 0 nm in diameter) and clear synaptic vesicles (around 45 nm in diameteO appeared in processes and accumulated at varicosities and synapses. This evidence indicates that the adrenal chromaffin cells develop ultrastructurally as neuronal cells in NGF containing medium.
IN THE SIMPLE OR COMBINED CULTURE OF DEVELOPING RAT CEREBRa!
TOSHIO SHIRAI I, KOICHIRO SASAKI I~ and SHIGEO A I Y A ~ 2 , 1 D e p a r t m e n t of Anatomy, Yamagata University School of Medicine, Yamagata 990-23, and 2Department of Anatomy, Nippon Dental College, Chiyoda-ku, Tokyo 102, Japan. Synaptic formation was studied in the explant of cerebrum, in which the neuronal architecture was maintained during cultivation, from the developing rat. Slices were dissected from the cerebrum, spinal cord and cerebellum of rat at 1 day after birth, and the cerebrum alone was placed on the collagen or the cerebrum in contact with the cerebrum, spinal cord or cerebellum. These simple and combined explants were cultivated in a CO 2 incubator for 3 weeks. By the first week many neurites were found to run in the simple explant and to connect between both combined explants: and these connections continued by third week. At day 21, the simple and combined cerebral explants were observed with the electron microscope. The several various types of axo-dendritic and axo-spinous synapses were almost observed in the simple and combined cerebral explants. A few compound types of axo-dendritic synapses were also found. But the distribution rate of these synapses was different in simple and combined explants. The synaptic formation in the combined explants was more increased than that in the simple explants. There were no differences of synaptic types and these distribution rate between three combined cultures. From these results it is suggested thst the increase of synaptogenesis in the combined cultures is involved with the in-put axons derived from neurons in other explants into cerebral explant.
THE TRANSDIFFERENTIATION CULTURE
OF ADRENAL CHROMAFFIN CELLS INTO NEURONAL CELLS IN
MASAHARU OGAWA *I, TOMOICHI ISHIKAWA .2 and HITOSHI OHTA .3, Department of Physiologyl, Dept. Anatany 2 and Dept. Neuropsychi. 3, Kochi Medical School, Nankoku, Kochi, 781-51. Cultured adrenal chromaffin cells differentiate into neuronal cells responding to the nerve growth factor (Unsicker et al. PNAS 75;3498 (1978)) and develop functional synapses among neuralized chrcmaffin cells (Ogawa et al. Nature 307, 66 (1984)). In this study we examined the ultrastructural changes accompanying the neural transdifferentiation of adrenal chromaffin cells in culture. Adrenal glands were removed from 8- to 10-day old rats, medullae were isolated from cortex and the cells were dispersed with enzyme treatment. After individual chromaffin cells settled onto the dish surface, fine unmyelinated processes grew out, responding to NGF. The growth of processes continued with time, and dense dendritic networks were formed after 2 weeks in culture. In early culture days, numerous chromaffin granules (up to 350 nm in diameter) were dispersed throughout the cytoplasm. With increased time in culture, the chromaffin granules decreased from the central area and localized the more peripheral area of the cytoplasm and extened processes. By 2 or more weeks, a number of ultrastructural changes were observed in the cell body; the content of heterochromatin decreased, and the over all density of the nucleus was reduced. Golgi complexes, mitochondria and especially rough endoplasmic reticula were considerably increased. Chromaffin granules progressively disappeared from cell bodies and processes, while dense core vesicles ( 6 0 ~ I 0 0 nm in diameter) and clear synaptic vesicles (around 45 nm in diameteO appeared in processes and accumulated at varicosities and synapses. This evidence indicates that the adrenal chromaffin cells develop ultrastructurally as neuronal cells in NGF containing medium.