Light and electron microscopic studies on the excessive growth of sympathetic ganglia in rats injected daily from birth with 6-OHDA and NGF.
Concomitatn daily treatment of rats immediately after birth with NGF and 6-OHDA for a period of 2-4 weeks, results in a volume increase of sympathetic ganglia of thirty times that of controls and 2.3 that of NGF treated littermates, at three weeks of age. Studies at the light, fluorescent and electron-microscope, showed that this overall enlargement is due to increase in size and number of sympathetic neurons and, to an even higher extent, to profuse production and branching of collaterals from postganglionic adrenergic nerve fibers. These axonal collaterals find accomodation inside the ganglia where they displace nerve cells and build a thick fibrillar capsule around the same ganglia. The survival in excellent conditions of sympathetic nerve cells treated with NGF but prevented by 6-OHDA from establishing anatomical and functional connections with their end organs, suggests that the growth factor find access to its target cells through the plasms membrane which envelops the cell perikarya. The extraordinary production of collaterals by chemically axotomized sympathetic fibers, brings to light growth potentialities of these fibers which materialize only upon disconnection of their endings from peripheral tissues. These results uncover a new facet of the interaction between nerve fibers and innervated tissues.
D000818:Animals; D000831:Animals, Newborn; D001835:Body Weight; D005260:Female; D005725:Ganglia, Autonomic / Q000166:cytology / Q000187:drug effects / Q000254:growth & development*; D006892:Hydroxydopamines / Q000008:administration & dosage / Q000494:pharmacology*; D008854:Microscopy, Electron; D009414:Nerve Growth Factors / Q000008:administration & dosage / Q000494:pharmacology*; D051381:Rats
D006892:Hydroxydopamines; D009414:Nerve Growth Factors