. Compendium of histology. Histology. So EIGHTH LECTURE. transversely striated has become further developed. The latter contracts rapidly and energetically, the former slow- ly and sluggishly ; the latter constitutes the voluntary mus- cle, the former the involuntary acting. The heart, with transversely striated involuntary fibres, makes, it is true, an exception. Pale, nucleated bands were formerly assumed to be the elements of the smooth muscles (Fig. 74, i). In the year 1847 Koelliker reduced the band into a series of cellular elements, lin- early arranged behind each other, his con- tracti
. Compendium of histology. Histology. So EIGHTH LECTURE. transversely striated has become further developed. The latter contracts rapidly and energetically, the former slow- ly and sluggishly ; the latter constitutes the voluntary mus- cle, the former the involuntary acting. The heart, with transversely striated involuntary fibres, makes, it is true, an exception. Pale, nucleated bands were formerly assumed to be the elements of the smooth muscles (Fig. 74, i). In the year 1847 Koelliker reduced the band into a series of cellular elements, lin- early arranged behind each other, his con- tractile fibre cells. At that time this was an important discovery, a proof of the dis- tinguished observer's sharp-sightedness. We perceive these contractile fibre cells at a to h. They are sometimes short, some- times longer, not infrequently immensely long, spindle-shaped structures, to mm. and more in length, and of moderate diameter, to mm. The appearance of the membraneless cell body is, as a rule, entirely homogeneous, except when a deposition of fat (It) has taken place within it. An elongated nu- cleus (it is called rod-like) is readily seen. fig. 75.—Two trans- Jt contains one or more nucleoli. Occa- versely striated muscular nbriite («), with the con- sionallvwe find the nucleus double or in nective-tissue bundles [l>). J even greater number. Smooth muscles are widely diffused throughout the human body. From the oesophagus till near the end of the rectum they form the long known thick muscular layer, and, besides, a still finer one—the muscularis mucosae—in the tissue of the mucous membrane. Smooth muscles are met with, further- more, in the respiratory apparatus, as in the posterior walls of the trachea, in the circular fibrous membrane of the bronchi and their ramifications. According to many, our tissue is not wanting even in the respiratory vesicles of the lungs,. Please note that these images are extracted from scanned page images
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Keywords: ., bookcentury1800, bookdecade1870, bookpublishernewyo, bookyear1876
