. Text-book of normal histology: including an account of the development of the tissues and of the organs. of nerve-cells lie embedded among thebundles of the nerve-fibres. ganglion of the trifacial nerve, or their size may be microscopic, asmany of the interstitial ganglia connected with the distribution ofthe sympathetic fibres. The outer covering of the ganglion consists of a fibrous envelope,a condensation of the adjacent epineurium in many cases, from which prolongations extend amongFig. 97. the nervous elements, where they break up into delicatebundles of connective tissue,which serve fo
. Text-book of normal histology: including an account of the development of the tissues and of the organs. of nerve-cells lie embedded among thebundles of the nerve-fibres. ganglion of the trifacial nerve, or their size may be microscopic, asmany of the interstitial ganglia connected with the distribution ofthe sympathetic fibres. The outer covering of the ganglion consists of a fibrous envelope,a condensation of the adjacent epineurium in many cases, from which prolongations extend amongFig. 97. the nervous elements, where they break up into delicatebundles of connective tissue,which serve for the unionand the support of the cellsand the fibres. Some of thenerve-fibres pass throughthe ganglion on their wayto more distant points with-out joining any of the nerve-cells, while many others endin or take origin from theseelements. The presence orabsence of the medullarycoat depends upon the char-acter of the componentfibres of the nerv^e-trunk;before joining a ner\e-cell,however, the medullary substance disappears, while the neuri-lemma of the fibre continues and becomes the nucleated capsule. Section of spinal ganglion more highly magnified :g, the nerve-cells, cut in various planes, surroundedby the nucleated sheath (c); a, the meduUated nerve-fibres, on which several nodes of Ranvier are seen ; b,cells of the supporting connective tissue. THE NERVOUS TISSUES. Fig. enclosing the individual nerve-cells. These latter possess, ingeneral, a spherical form, and are usually provided with one or two,seldom more, processes ; in the bipolar cells the processes frequently-pass from opposite poles to become continuous with the afferentand efferent fibres. In the ganglia of some of the lower vertebratesbipolar cells occur in which one process becomes invested by theturns of the other or spiral fibre. Unipolar cells exist in which thesingle process divides into T-branches extending almost at rightangles ; such cells occur also in man. The development of all nerve-fibres and nerve-
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