Ultrastructural features of adult human tendon

Abstract

A variety of human tendons have been studied at the electron microscope level. The fibers of these tendons are composed of collagen fibrils that average 1,750 A and 600 A in diameter. A third population that measures 100 A in diameter may represent immature collagen or filaments that are incorporated into tendon elastic fibers. The larger collagen fibrils vary in ratio with respect to one another, and are connected by interfibrillar bridges which in some cases appear to extend through the substance of the fibril. The collagen fibrils of the paratenon are less-well organized than those of the tendon proper and average 600 A in diameter. Tendons that exhibit the property of lateral stretch (plantaris and palmaris) were compared at the ultrastructural level with tendons that do not have this property. No differences between the two tendon types could be determined in normal or spread preparations, indicating that the differences in physical characteristics are a result of fiber rather than fibril organization.

Analysis of the Tendinous Structure in Human Masticatory Muscles

“…For example they are larger than human tendons of other skeletal muscles [6). This is espe cially true in the superficial portion of the masseter mus cles, where the homogeneous collagen fiber size of tendon is large in contrast with the heterogeneous collagen fiber size (large and small) in other portions and in other masti catory muscles.…”

“…This is espe cially true in the superficial portion of the masseter mus cles, where the homogeneous collagen fiber size of tendon is large in contrast with the heterogeneous collagen fiber size (large and small) in other portions and in other masti catory muscles. These heterogeneous fibers are similar to the tendon of other skeletal muscles [6], rat skeletal mus cles and the rat masseter muscles [7], The microfibrillar arrangement and wide range of diameters and thick bun dles of tendon (type 1) are suitable to the stress of being stretched [8]. The structure of collagen fibril bundles or organization, i.e.…”

Distribution of Elastic System Fibres in the Rat Tail Tendon and Its Associated Sheaths

“…Since then, various studies have disclosed by electron micros copy the presence, in many tendons, of bundles of unbranched microfibrils (10-14 nm in diameter) which exhibited a hollow appearance, similar to those observed in elastic fibres [1,15,17]. These pure microfibrillar bun dles correspond to the current view on the fine structure of oxytalan fibres.…”

“…Although, since then, several reports have described the presence of clastic fibres among the collagen fibrils within the tendon fascicle [8][9][10], it was only recently that the presence of elastic fibres was detected in tendon sheaths, too [11, 121. When describing the elaunin fibres, Gawlik 113] reported their presence in the human tendon. Although the presence of elaunin fibres in tendons has not been reported by them, a close examination of the-electron micrographs in the papers by Cooper and Misol 114| and by Dyer and Enna [ 15] shows that the ultrastructural fea tures of some of the fibres closely resemble those of elaunin fibres.…”

Tendon�s ultrastructure

“…Electron microscopy of longitudinally oriented tendon specimen shows a parallel arrangement of collagen fibrils. The ratio of collagen fibril sizes in human tendon is variable from 1,750 to 600 and 100 A diameter 13,17 . However, it is difficult to link the size of collagen fibrils with different zone of the tendon 17 .…”