Mixture Of Tannic Acid Research Articles

Development of the basal lamina and extracellular materials in the early chick embryo.

Chick embryos at developmental stages up to primitive streak formation were fixed in a mixture of tannic acid and glutaraldehyde. A basal lamina was present in the unincubated embryo and consisted of a lucent lamina interna and a lamina densa. At the primitive streak stage the lamina densa showed a periodicity of stained elements. Densely stained materials were present on the cell surfaces lining the cavity between the epiblast and endoblast, and on the mesoderm cells within this cavity. Considerable amounts of extracellular material were observed in the cavity. Hyaluronidase treatment removed the cell surface and extracellular material, indicating that hyaluronic acid is a major component. This enzyme disrupted the basal lamina, leaving a fibrillar remnant with no periodic structure. It is therefore suggested that the dense periodicities consist of glycosaminoglycan built on an enzyme-resistant framework which is probably collagen. Enzyme-resistant fibrils, presumably collagen precursors, are present elsewhere within the tissue spaces.

The preservation of membranes of tubular bodies associated with mycoplasmalike organisms by tannic acid

Fixation with a mixture of tannic acid and paraformaldehyde–glutaraldehyde resulted in an increased electron density of the membrane structure of tubular bodies that were associated with mycoplasma organisms (MLO) in Vinca rosea plants infected with the Alberta isolate of the aster yellows agent. The tubular bodies, 25.5 ± 4.3 nm in diameter, were bounded with membranes in contrast with the hollow cylinders of 12.3 ± 3.0 nm in conventional fixation. In the study of physical relationships, the tubular bodies were often connected with MLO by a common unit membrane. Some subtubules were formed from a main tubular body.

Tannin‐osmium conductive staining of biological specimens for non‐coated scanning electron microscopy

AbstractOsmication of biological specimens with a mixture of tannic acid, guanidine hydrochloride, arginine hydrochloride and glycine imparted sufficient electron conductivity to permit SEM observations of non‐coated samples. No charging was noted at 25 kV acceleration voltage and 1 × 10−10 A specimen current in rat kidney specimens. The foot‐processes of the glomerular podocytes were clearly visible without metal coating. This tannin‐osmium method even allowed block staining and enabled continuous observations during and after dissection in the SEM.

The use of a tannic acid—glutaraldehyde fixative to visualize gap and tight junctions

Fixation of livers from mice with a mixture of tannic acid and glutaraldehyde resulted in an increased density of the cell periphery. Gap and tight junctions were well demonstrated by this method. The gap junctions were filled with a homogeneous, electron-dense precipitate. Faint electron-lucent lines spaced 100 A center-to-center crossed the gaps. In oblique sections of gap junctions an array of round particles was seen. The tight junctions appeared as membrane fusions preventing the passage of the tannic acid from the intercellular clefts to the bile canaliculi. Morphologically, the results obtained by using tannic acid as a tracer are similar to those obtained with lanthanum and ruthenium red, but chemically the tannic acid may act in a different way, thus representing an “alternative” tracer.