Plexus, nerve terminals

Autonomic nerve endings are in fact only rarely seen in peripheral tissues. Instead anatomical studies reveal a complex highly branched network of fine nerve fibres (Fig. 1, p. 110). In this network, or ground plexus , nerve terminal fibres run in bundles of 2-4, largely surrounded by Schwann-cell cytoplasm, but also in close apposition to the cells of the innervated tissue. It is likely that a single nerve fibre has functional synaptic connections with many effector cells en passage with spaces of up to 500 A between nerve fibre and effector cell being not uncommon. 

Peripheral Cholinergic heteroreceptor -myenteric plexus Peripheral Vascular smooth muscle, autonomic terminals Peripheral autonomic and trigeminal nerve terminals Peripheral None identified ... 

Subsequent to the molecular cloning and cDNA sequence analysis of the delta opioid receptor, antireceptor antibodies were raised against synthetic peptides based on the deduced amino acid sequence of this receptor. To date, there have been a limited number of studies using antibodies directed toward the amino terminus of the cloned murine receptor to assess the distribution of delta opioid receptorlike immunoreactivity in the gastrointestinal tract, and these have been confined so far to the porcine small intestine. They have shown the presence of delta opioid receptor-immuno-reactive neurons and fibers in both the myenteric and submucosal plexuses and as well as in myenteric neurons maintained in primary culture [22, 23]. Receptor-like immunoreactivity in neuronal cell bodies appears to be localized in the cytoplasm and is likely to be trafficked to nerve terminals. These neurons are coimmunoreactive for the acetylcholine-synthesizing... 

In an electron microscope study Shute and Lewis (1966) found most of the AChE to be presynaptic. Scattered local neurones (Golgi type II cells) in hilus fasciae den-tatae and stratum oriens stained for AChE. Terminals on the bodies of the pyramidal and granular cells, i.e., the inhibitory terminals of the basket cells, were as a rule devoid of AChE. Further, they observed that AChE-positive nerve terminals were less numerous than AChE-positive thin nerve fibres, and concluded that the pattern of AChE staining reflected the distribution of an AChE-containing preterminal nerve plexus rather than that of AChE-containing boutons. 

Larsell O (1921) Nerve termiunation in the lung of the rabbit. J Comp Neurol 33 105-131 Larsell O (1922) The ganglia, plexuses and nerve-termination of the mammalian lung and pleura pulmonis. J Comp Neurol 35 97-132... 

A 60-year-old 70 kg woman with a fractured radius had an axillary brachial plexus block for postoperative analgesia after uneventful general anesthesia (5). A 50 mm insulated regional block needle attached to a nerve stimulator was used to locate the brachial plexus, and after negative aspiration, levobupivacaine 125 mg was injected with intermittent aspiration. Within 30 seconds the patient had a generalized tonic-clonic seizure which lasted about 30 seconds and self-terminated. She remained car-diovascularly stable and made an uneventful recovery. 

Thyroxine (T4) enters the extracellular fluid space through blood brain barrier (11) and the choroid plexus (12) delivery systems. The potentially important role of the latter system has become a matter of considerable interest, following the demonstration of Dickson et al that T4 binding pre-albumin (transthyretin) is strongly localized and independently controlled within choroid plexus cells (]2). T4 (and any T3 entering the brain) is transported from the extracellular fluid space into groups of selected nerve somata and their axonal and dendritic terminals (synaptosomes), Moreover, with time after i.v. administration of a T4 or a T3 pulse, there is progressive accumulation of iodothyronines in synaptosomal particles (Fig.l). 

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