292 



STRUCTURE OF A VILLUS. 



spaces of the adenoid tissue, where they become loaded with fatty granules, and pass into the 



c b - - A B 



Fig. 208. 



A, scheme of a transverse section of part of a villus ; a, columnar epithelium with, b, clear disc ; 

 c, goblet-cell ; i, i, adenoid reticulum ; d, d, spaces containing leucocytes, e, e ; /, section 

 of the central lacteal. B, scheme of a cell with processes projected from its, interior. C, 

 columnar epithelium after the absorption of fatty granules. D, columnar epithelium of a 

 villus seen from above with a goblet-cell in the centre, 

 central lacteal. Zuwarykin and Wiedersheim suppose that the leucocytes pass from the 



parenchyma of the villus towards 

 c the epithelial layer, and even be- 



cal epi" tween the epithelial cells, from 

 thelium. which they return towards the axis 

 of the villus, laden with substances 

 which they have taken into their 

 Disc on interior ( 192, II.). 

 the epi- A small artery placed eccentrically 

 theliuin. passes into each villus (fig. 209). In 

 man it begins to divide about the 

 middle of the villus, but in animals 

 it usually runs to the apex before it 

 divides. The capillaries resulting 

 from the division of the artery form 

 a fine dense network placed super- 

 ficially, immediately under the epi- 

 thelium of the surface. The blood 

 is carried out of a villus by one or 

 two veins (figs. 207, 209). 

 Non-striped muscular fibres are 



f)resent in villi. They are arranged 

 ongitudinally in several bundles 

 from base to apex, immediately out- 

 side the central lacteal. When they 

 contract they tend to empty the 

 lacteal. A few muscular fibres are 

 placed more superficially, and run in 

 a more transverse direction. [The 

 longitudinal bundles of non-striped 

 muscle in the villi are connected 



Capillary. 



Artery. _ 



Vein. 



Fig. 209. 

 Injected blood-vessels of a villus, 

 together by oblique strands; while the longitudinal bundles shorten the villus, the oblique 



