The intraglandular submandibular ganglion of postnatal and adult rats. I. A light and electron microscope study.

The structure of the intraglandular submandibular ganglion is described in both postnatal and adult rats. The ganglion is localised mainly at the hilum where the majority of the cell bodies are observed. Ganglia are also present in the intralobular septa of both the submandibular and the sublingual glands. Often they are found along the main salivary ducts with the larger ganglia being encapsulated by connective tissue. On electron microscopy, the submandibular ganglion cells show the usual features of autonomic neurons. The cells contain a prominent round nucleus. Numerous short processes project from the soma together with a few long dendrites. The organelles are randomly distributed throughout the soma. Most of the synapses observed were on the short processes with occasional axosomatic synapses. Nonsynaptic desmosome-like contacts are a common feature among the ganglion cells. Especially noteworthy are contacts made by the dendrites which deeply invaginate the soma of an adjacent nerve cell. The ganglion cells of the postnatal and adult submandibular ganglia show minor differences. Ultrastructurally, the postnatal cells show signs of immaturity such as abundant free ribosomes, well developed Golgi complexes and disorganised rough endoplasmic reticulum. Mitotic satellite cells were observed associated with the postnatal ganglion cells. The study has confirmed that all the submandibular ganglion cells show a positive reaction for acetylcholinesterase. Enzyme activity is localised in the cisternae of rough endoplasmic reticulum, the Golgi complex, plasma membrane and nuclear envelope.