. Compendium of histology. Histology. 94 NINTH LECTURE. In the smaller arteries, the serosa and adventitia remain toler- ably unchanged. Still, there frequently occur in the former reticular perforated elastic layers, so-called " fenestrated mem- branes," or free elastic longitudinal reticula; the media pre- sents several layers of transversely directed muscles, lying over each other, and an elastic net-work is also developed in the fihrillated outer layer. In the larger branches, the stratification of the inner and middle layers increases. In the latter, elastic plates with transver
. Compendium of histology. Histology. 94 NINTH LECTURE. In the smaller arteries, the serosa and adventitia remain toler- ably unchanged. Still, there frequently occur in the former reticular perforated elastic layers, so-called " fenestrated mem- branes," or free elastic longitudinal reticula; the media pre- sents several layers of transversely directed muscles, lying over each other, and an elastic net-work is also developed in the fihrillated outer layer. In the larger branches, the stratification of the inner and middle layers increases. In the latter, elastic plates with transverse fibres, are now interpolated between the muscular layers, and the elastic reticulum of the adventitia becomes thicker. The largest arteries (Fig. 90') show under the endothelium (a), strongly stratified, the group of the inner vascular mem- brane (b). The several lamel- lae, in varying texture, present the entire multifariousness of the elastic tissue. Inwards, towards the endothelial cover- ing, one may, indeed, meet with more homogeneous, or more striated layers with cellu- lar reticula imbedded over each other (Langhans, von Ebnen. In the more middle group of layers the membranous character of the elastic fibrous net-work (d) becomes more and more prominent. Their fibres may be thinner or thick- er; the membranous connect- ing substance may appear whole or perforated. The num- ber of these elastic layers may increase to 30, 40, 50, and more. The muscles of the middle layer (e) appear unequally developed ; frequently not. e m Fig. 90.—Transverse section through the walls of a large artery : a, endothelium ; /. sa ; c. outer layer of the same ; d. elastic, e, mus- cular layers of the media : g, adventitia ;/, their elastic Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Frey, Heinrich,
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