Olfactory granule cell development in normal and hyperthyroid rats.
Dendritic development was examined in olfactory bulbs of both normal 7-, 14-, 21- and 60-day-old rats and littermates treated on postnatal days 1-4 with 1 microgram/g body weight of L-thyroxine sodium. Tissue was processed via the Golgi-Cox technique and subjected to quantitative analyses of mitral and internal layer granule cell development. These populations of granule cells were selected because their pattern of late proliferation suggested potentially greater susceptibility to postnatal hormonal alterations. Although neonatal hyperthyroidism induces widespread acceleration of maturation, including precocious chemosensitivity, granule cell development was unaffected relative to littermate controls. Both normal and hyperthyroid groups exhibited an inverted U-shaped pattern of cellular development, with rapid dendritic dendritic growth and expansion occurring during the earliest ages tested, but with loss of processes and dendritic field size occurring after day 21.
D000375:Aging; D000818:Animals; D003712:Dendrites / Q000502:physiology; D005260:Female; D006980:Hyperthyroidism / Q000503:physiopathology*; D008297:Male; D009474:Neurons / Q000502:physiology*; D009830:Olfactory Bulb / Q000254:growth & development* / Q000473:pathology; D051381:Rats; D013974:Thyroxine
D013974:Thyroxine