Factors regulating development of an embryonic mouse sympathetic ganglion.

Embryonic development of the mouse superior cervical ganglion (SCG) is defined in vivo and in vitro using morphologic, morphometric, and biochemical approaches. Catecholamine fluorescence was present in the SCG on Day 14 of gestation and underwent characteristic changes in distribution among neurons between this time and adulthood. During prenatal ontogeny, choline acetyltransferase (ChAc) activity increased 2-fold, while tyrosine hydroxylase (T-OH) activity rose 30-fold and total protein increased 4-fold. Ganglionic explants from 14-day embryos extended neurites and exhibited specific biochemical development in medium without added nerve growth factor (NGF). However, the addition of NGF further stimulated neuronal development: Ganglia exhibited significant increases in ChAc and T-OH activities and in total protein compared to controls grown in medium without added NGF. The presence of target submandibular gland radically altered development of T-OH activity in cultured sympathetic ganglia. By 5 days in culture, ganglia grown with target tissue, even in the presence of anti-NGF, exhibited a 10- to 15-fold increase in T-OH activity compared to zero-time controls, and a 2-fold increase over ganglia grown alone or with nontarget tissue. Ganglia grown with target salivary glands showed a correspondingly greater elaboration and directionality of nerve fiber outgrowth, even in the presence of anti-NGF.