TISSUES, ORGANS, AND SYSTEMS. 99 



pansions, which remains of the original formative cells, have, re- 

 cently, less properly been considered to be ganglion-globules.] 



Literature. — G. Valentin, 'On the course and termination of 

 the nerves/ in the f Nov. Act. Natur. Curios./ vol. xviii, t. i; 

 R. Remak, ' Observations anatomicse et microscop. de syst. 

 nerv. struct./ Berol., 1838; A. Hannover, 'Recherches naicro- 

 scopiques sur le systeme nerveux/ Copenhague, 1844; R. 

 Wagner, ' Neue Unters. iiber den Bau und die Endigungen 

 der Nerven und die Structur der Ganglien/ Leipzig, 1847 ; and 

 'Neurologische Untersuchungen/ in 'Gottingen Anzeige/ 1850; 

 Bidder and Reich ert, 'Zur Lehre vom Yerhaltniss der Ganglien- 

 korper zu den Nervenfasern/ Leipzig, 1847; Ch. Robin, in 

 ' l'Institut./ 1846, Nos. 687 — 699, and 1848, No. 733 ; Kolliker, 

 ' Neurologische Bemerkungen/ in ' Zcitsch. fiir wiss. Zool./ i, 

 p. 135. 



§ 29. 



True Glandular Tissue. — The most essential constituents of 

 the true glands are the secreting elements, which appear as 

 aggregations of cells, as closed glandular vesicles, and as open 

 glandular vesicles and glandular tubes, containing as their 

 most important constituent the so-called gland-cells. These 

 cells are for the most part polygonal or cylindrical, and per- 

 fectly resemble certain epithelial cells, but upon the other 

 hand, they are frequently distinguished and characterised by 

 peculiar contents. The union of these cells into the secreting 

 parts of the glands is effected either directly or with the co- 

 operation of homogeneous membranes, the so-called membrance 

 propria, and of connective tissue. In this manner the secreting 

 glandular elements, different in nature according to the different 

 glands, are formed ; and becoming invested with vessels, nerves, 

 and connective tissue, with which elastic fibres, fat cells, and 

 even muscles, are mingled; they are combined into the larger 

 and smaller divisions of the glands. The principal forms of 

 the secreting glandular elements in man are the following : 



1. Solid networks of cells without investing membrane. In 

 the liver (fig. 40). 



2. Closed vesicles with a fibrous membrane and an epithelium. 

 Graafian vesicles, mucous follicles (so-called ovula Nabothi), in 

 the cervix uteri. 



