CONNECTIVE TISSUE. 



57 



2. Tendinous tissue. Longitudinal bundles of a fibrillary 

 connective tissue with an elastic boundary layer arranged in 

 a compact manner are met with. Between them one recog- 

 nizes in transverse sections a system of indented and stellate 

 spaces. In these lie, arching over the connective-tissue 

 bundles, ordinary lamelliform and shovel-shaped connective- 

 tissue cells, and also isolated lymphoid corpuscles. Only 

 scanty, fine, elastic fibres occur in this extremely bloodless 

 tissue. 



3. The ligaments are, with the exception of the elastic, 

 formed like the tendons. 



4. The connective-tissue cartilage (see p. 45). 



5. The so-called fibrous membranes. Firmly woven, non- 

 vascular structures with a varying intermixture of elastic ele- 

 ments. Among these are the dura mater of the brain and 

 spinal cord, the sclerotic of the eye ; the firm envelopes of 

 many organs, for example, of the kidneys, testicles, and 

 spleen ; furthermore, the fasciae of the muscles, the coverings 

 of the nerve trunks (the perineurium or neurilemma), the 

 covering of the cartilage and bone (the perichondrium and 

 periosteum). The latter is permeated by numerous blood- 

 vessels, but which serve principally for the nutrition of the 

 invested bone. 



6. The serous membranes, which formerly were erroneously 

 considered as entirely closed sacs, consist of a but slightly 

 vascular net-work of connective-tissue bundles, occasionally 

 with a considerable contingent of elastic-reticular fibres. The 

 free surface is covered by endothelium. To this variety be- 

 long the pleura, pericardium, peritoneum and tunica vaginalis 

 propria of the testicle. As more incomplete structures, we 

 mention the arachnoid membrane of the brain and spinal 

 cord, the synovial capsules (having a serous membrane only 

 at the sides, and here covered by a simple layer of epithelial 

 cells), and also the mucous pouches and the sheaths of the 

 tendons. The serous cavities, like the passages between the 

 connective-tissue bundles, must be regarded as belonging to 

 the lymphatic apparatus, as we shall perceive hereafter. 



3* 



