List of abbreviations

Vocabulary of micros- copic anatomy specialist terms explained in English + German

Every attempt was made to provide correct information and labelling, however any liability for eventual errors or incompleteness is rejected!

dieser Seite Editor: Dr. med. H. Jastrow

Conditions of use

myelinated and non-my- elinated axons (monkey)	myelinated nerve fibre + Schwann cell (monkey)	inner + outer mesaxon on myelin sheath (monkey)	detail 1: inner mes- axon (monkey)	detail 2: outer mesaxon (monkey)	myelin sheath of a fibre in vestibulo- cochlear nerve (guinea pig)

node of Ranvier in cross- section (monkey)	node of Ranvier in longi- tudinal section (monkey)	idem + Schmidt-Lanter- man incisure (monkey)	node of Ranvier in longi- tudinal detail (monkey)	node of Ranvier 1 (rat)	node of Ranvier 2 (rat)

myelinated nerve fibre Schwann cell 1 (rat)	myelinated nerve fibre + Schwann cell 2 (rat)	human myelinated nerve fibre	noradrenergic innervation of a smooth muscle cell (rat)	Schmidt-Lanterman's incisure in longitudinal section (monkey)

non-myelinated nerve of Tela submucosa, stomach (rat)	non-myelinated nerve fibres (rat)	non-myelinated nerve fibres in a Schwann cell, colon (rat)	ureter, Tunica adventitia: loose connec- tive tissue + non myelinated nerve (pig)	non-myelinated nerve in con- nective tissue, parotid gland (rat)

Plexus myentericus, ganglion cell (rat)	part of the nervus vagus (rat)	detail thereof: mainly non-myelinated fibres	epineurium of the nervus vagus in the adventitia of esophagus (rat)	epineurium vagus nerve (rat)	non meylinated nerves of the Plexus submucosus (rat)	detail thereof in L. propria mucosae

A nerve (Terminologia histologica: Nervus) thus is defined as a bundle of processes of nerve cells, here peripheral nerve fibres (Terminologia histologica: Neurofibrae periphericae) with the surrounding layers of connective tissue. In case of larger nerves when looking from outside to inside we can distinguish the following
layers:
1. The epineurium (Terminologia histologica: Epineurium) ensheats the entire nerve and is in continuity with the dura mater (pachymeninx; Terminologia histologica: Dura mater, Pachymeninx). It nourishes and protects the nerve proper. The epineurium has a superficial layer called superficial epineurium (Terminologia histologica: Epineurium superficiale) consisting of irregular woven connective tissue which is connected to surrounding connective tissue and a deeper layer called deep epineurium (Terminologia histologica: Epineurium profundum) of loose connective tissue with intermingled unilocular adipose cells, elastic networks with arterioles and venules, their supplying non-myelinated autonomic nerve fibres as well as small vessels responsible for blood supply. The elastic networks allow a certain flexibility of the nerve and cause its retraction in case of being cut. The epineurium covers many fasciles (bundles of nerve fibres with some to some hundred single fibres) and is in continuity with the connective tissue sheath of the
2. perineurium (Terminologia histologica: Perineurium). This layer has an outer mechanically resistant layer of dense woven connective tissue called fibrous part (Terminologia histologica: Pars fibrosa) onto which the epithelioid part, i.e. the perineural sheath (Terminologia histologica: Pars epitheloidea) is attached. This layer consists of up to 12 layers of very long, flat perineural cells (missing in Terminologia histologica; proposal: Perineurocyti) which are surrounded on all sides by basal laminas and connected to each other by spot- and belt desmosomes as well as by tight junctions. This is only the case in longitudinal direction and to the lateral edges by not to covering or underlying cells which results in formation of tubular sheath layers inside the epitheloid part. The cells are rich in caveols, glucose transporter type 1 (Glut-1) and by means of their tight junctions establish a functionally relevant diffusion barrier for hydrophilic substances. The 200 nm wide spaces between the cells is filled with collagen fibrils mainly in parallel orientation and few elastic fibres. The perineurium is maintained even in small branches of nerves though it constantly reduces in in thickness until it finally gets lost at the small terminal branches or it joins the capsular structures of specialised nerve terminals like Meissner's corpuscules, Vater-Pacini bodies and others. The innermost layer which is located beyond the perineurium is the
3. endoneurium (Terminologia histologica: Endoneurium) which consists of loose connective tissue. It fills the space between the single nerve fibres which are enscheated by Schwann cells and thus covered by a basal lamina. The endoneurium contains some fibrocytes few fibroblasts, macrophages and mast cells. The collagen fibrils in the endoneurium are usually oriented parallel to the nerve fibres and are embedded in fundamental substance which is poor in proteins and centrally reaches the cerebrospinal fluid while in the periphery it opens into the connective tissue which surrounds the nerve endings. This is why it may carry e.g., herpes zoster viruses from spinal ganglia into the dermatome of a nerve which then gets visible as shingles (acute posterior ganglionitis). The endoneurium further may contain capillaries, few metarteriols and small venules.

--> node of Ranvier, Schmidt-Lanterman incisure, inner and outer mesaxon
--> nerve tissue, Schwann's cells, neuromuscular junction, classification of nerve fibres, CNS
--> Electron microscopic atlas Overview
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