. The cyclopædia of anatomy and physiology. Anatomy; Physiology; Zoology. Tesselated appearance of columnar epithelium lining the pancreatic duct. (Magnified 200 diameters.) The epithelium is columnar, arranged ap- parently in a single stratum, and presenting a beautiful honeycomb appearance of closely- packed hexagons and pentagons, when looked at on its free surface. Further up, however, near the extremities of the ultimate ducts, the epithelium changes its character, and becomes more globular, as is shown in Jig. 63, which represents a portion of the epithelial lining of a duct, about ^-^ o
. The cyclopædia of anatomy and physiology. Anatomy; Physiology; Zoology. Tesselated appearance of columnar epithelium lining the pancreatic duct. (Magnified 200 diameters.) The epithelium is columnar, arranged ap- parently in a single stratum, and presenting a beautiful honeycomb appearance of closely- packed hexagons and pentagons, when looked at on its free surface. Further up, however, near the extremities of the ultimate ducts, the epithelium changes its character, and becomes more globular, as is shown in Jig. 63, which represents a portion of the epithelial lining of a duct, about ^-^ of an inch dia- meter, from the human subject. A certain ap- proximation is here seen to the form of se- creting epithelium, with which, however, it strongly contrasts in its clearness and free- dom from granular contents. Fig. Portion of epithelium lining a small duct ^th of an inch in diameter. From a Rabbit. (Magnified 300 diameters.) There is every probability of the existence of a basement membrane here as in other sub-epithelial situations, and it is probably continuous with that which alone constitutes the walls of the ultimate ducts : for the fibrous and muscular elements gradually diminish as the ducts get finer, until in the smallest that are seen all fibrous appearance has vanished, and a homogeneous membrane alone remains. According to Henle the homogeneous wall of the smallest ducts consists of fibres fused and run together in a plane; — a supposition that would imply the non-existence of this mem- brane in the larger ducts, where they are not so fused. Capillaries. — The arrangement of the ca- pillaries remarkably resembles that of fat. They form a close and pretty even-meshed net work, open on all sides, among the meshes of which the follicles lie, just as the vesicles do in the case of fat; so that the closeness of the plexus is a measure of the size of the follicles. Their general appearance is well seen in the accompanying figure (Jig. 6-t.). Fig. 64.
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