The response of the rabbit subsynovial connective tissue to a stress-relaxation test.

The subsynovial connective tissue (SSCT) in the carpal tunnel may play a role in the etiology of carpal tunnel syndrome (CTS), yet the material properties of the SSCT remain unclear. Thus, we investigated the mechanical response of the SSCT in a rabbit model. Twenty-four rabbit cadaver paws were used for mechanical testing; two paws were used for scanning electron microscopy (SEM) imaging. After testing normal tendon excursion, the divided third digit flexor digitorum superficialis (FDS) tendon was pulled to displacements of 2, 3.5, 5, or 8 mm, maintained at that position until force decay, and then the process was repeated. Normal excursion of the FDS averaged 4.8 mm. The ratio of the second peak force to the first peak force in the 2 mm group was 0.98 (SD = 0.16), which was significantly higher than the other groups (3.5 mm: 0.74, 5 mm, 0.63, and 8 mm: 0.59; p < 0.05). SEM showed ruptured fibrils in the displaced specimen. The declining force ratio with displacements >2 mm suggests damage to the SSCT within the physiological tendon excursion. These data may be useful in understanding SSCT mechanics in CTS, which is associated with SSCT fibrosis.

The mole's thumb -- evolution of the hand skeleton in talpids (Mammalia).

Osteological specimens representing 15 out of the 16 currently recognized talpid genera were examined and scored for seven discrete morphological characters of the hand. The phylogenetic distribution of these characters was studied in the context of alternative hypotheses of talpid relationships, using three species of shrews and a hedgehog as outgroups. All talpids show a similar number and arrangement of carpal bones. The most obvious differences concern the presence of additional sesamoid bones, the relative size of the os falciforme when present, and the degree of fusion of the scaphoid and lunate in the proximal carpal row. Marked differences in the relative length and proportions of the metacarpals also exist. The development of the carpals in Talpa europaea was studied through examination of histological sections of the hand of an embryo and a neonate. Whereas carpal anatomy in the neonate mirrors the arrangement and proportions of the adult, in the embryo the scaphoid and lunate are still separate, there are no signs of the os falciforme, and the size proportions of metacarpals to carpals are obviously different to those of the adult. A prehallux or tibial sesamoid, serial homologue to the os falciforme or prepollex (a radial sesamoid), does not have an obvious functional role, and its presence might be the result of a common epigenetic control in the hand and the foot resulting in a non-adaptive structure in the latter.

Synovial membrane microarthroscopy of the equine midcarpal joint.

OBJECTIVE: To evaluate the value of microarthroscopy in the equine midcarpal joint using the vital stains methylene blue, trypan blue, neutral red, and Janus green B to observe components of the synovial lamina propria, vascular architecture, and synoviocytes. STUDY DESIGN: Experimental. ANIMALS: Ten horses. METHODS: Microarthroscopy of left and right midcarpal joints was performed with and without vital staining of the synovium. Four vital stains (methylene blue, trypan blue, neutral red, and Janus green B) were evaluated, with each stain used in 5 joints. Synovial biopsy specimens were collected from the dorsomedial and dorsolateral aspects of the joint. RESULTS: All dyes were biocompatible. At x 60 without vital staining, synovial surface topography, vascular network, and translucency were observed. Intra-articular vital dyes improved evaluation of synovial surface topography. At x 150 with vital staining, individual synoviocytes were clearly identified with all dyes, except neutral red. Although methylene blue provided the best in vivo microscopic differentiation of the structure of the intima, trypan blue had superior retention in conventionally processed synovial biopsies. CONCLUSIONS: Methylene blue, trypan blue, neutral red, and Janus green B stains can be used safely for microarthroscopy. Good visualization of cells and vascular network can be obtained by microarthroscopy, and microarthroscopic evaluation of the synovium compares favorably with conventional histologic evaluation of biopsy specimens. CLINICAL RELEVANCE: Microarthroscopy may be beneficial in both research and clinical diagnosis of equine articular diseases.

Ultrastructural immunolocalisation of bone sialoprotein in the osteocartilagenous interface of the equine third carpal bone.

REASONS FOR PERFORMING STUDY: One of the most common causes of lameness in racehorses is osteoarthritis (OA). Pathogenesis is not clear and pathological processes of the different joint tissues interact in often progressive events. The interface between cartilage and newly synthesised bone has been shown to be particularly enriched in bone sialoprotein (BSP), a cell-binding matrix protein. OBJECTIVES: To establish whether changes in the concentration of BSP may serve as a marker for early biochemical changes of the subchondral bone. METHODS: Articular cartilage, cartilage/bone interface and subchondral bone of the proximal third carpal bone from 3 Standardbred trotters were analysed ultrastructurally for the presence of BSP in normal and degenerative areas. RESULTS: A marked increase of BSP in the cartilage/bone interface with degenerative changes of the bone and cartilage compared to the morphologically intact cartilage/bone interface was noted, but levels of the protein were distinctly lower in the distal bone. CONCLUSIONS: The results indicate that BSP has the potential to be used as a marker for changes in bone metabolism in the subchondral bone. POTENTIAL RELEVANCE: Tools to monitor early biochemical changes within the connective tissues of the joint in vivo are essential in studies of the pathogenesis of OA. These could be used to monitor and understand such changes in relation to load, exercise, training programmes, inflammation and the development of OA.

Formation of the arthrodial membrane in the blue crab, Callinectes sapidus.

In this study the pattern of arthrodial membrane deposition in Callinectes sapidus was determined by histological and ultrastructural examination of tissues from the carpus joint of the cheliped collected during premolt, ecdysis, postmolt, and intermolt. Apolysis in the arthrodial membrane occurs at stage D(0) and is synchronous with apolysis of the calcified cuticle. Epicuticle formation begins at early stage D(1) and is completed in late stage D(1). Procuticle deposition starts at D(2) and continues until ecdysis. Numerous cytoplasmic extensions occur throughout the lamellae. Component fibers of the arthrodial membrane are intimately associated with dense plaques on the apical membrane of the underlying hypodermal cells, suggesting a site for fiber polymerization. Deposition of the arthrodial membrane continues after ecdysis, with most of the cuticle thickening occurring during stage C. When stained with PAS and counterstained with hematoxylin, a difference can be discerned between preecdysial and postecdysial procuticle of the arthrodial membrane, a distinction not made in previous studies. The boundary between the arthrodial membrane and calcified cuticle is thicker than either of the two layers and the layers overlap rather than butting up against one another. This pattern suggests that underlying hypodermal cells have to produce multiple types of cuticle over the molt cycle. A summary of the various molting patterns in C. sapidus suggests that the control of these diverse events may prove to be complex.

Histology, ultrastructure and carbohydrate histochemistry of pig carpal glands.

The morphological differences between two types of secretory cells (clear and dark) from pig carpal glands were examined. The main difference is the presence in the dark cells of secretory granules of moderate electron density, made up of acidic and neutral glycoproteins. The possible functional purposes of the carpal glands and of glycogen present in both cell types are also discussed.