Enhanced phagocytic activity of lymph node macrophages after intranodular injection of autologous red blood cells

Rabbits were killed 1 h to 12 days after injection of washed autologous red blood cells (RBC) into the paratracheal cervical lymph nodes. Microscopic, electron-microscopic, and histochemical techniques were used to study the time-dependent ingestion and digestion capacity of phagocytes in the lymph nodes. One hour after intranodular injection of RBC, a greater portion of the target cells had already attached to the surface of and were partly ingested by sinusoidal phagocytes in the marginal zone and medulla. After 6 h, degradation of erythrocyte hemoglobin into hemosiderin could be demonstrated in a few of the cells. After 9 days, erythrocytes, erythrophages, and hemosiderophages had disappeared and could no longer be observed in the lymph nodes. Comparative morphological and histochemical studies showed these phagocytes to be macrophages. The possibility of an opsonizing or a humoral factor in lymph serum which stimulates phagocytosis was excluded in in vitro studies (peritoneal macrophages incubated with lymph serum and RBC) and the possibility of phagocytosis induced by a T-cell-macrophage interaction, was excluded in in vivo studies with athymic nude mice. Comparable enhanced phagocytic activity of lymph node macrophages could be observed in vitro after injection of RBC into isolated lymph nodes of rabbits. The finding presented here indicate that marginal zone and medullary macrophages are primarily activated and that they eliminate autologous RBC from the sinuses without any additional stimulus by mechanisms which have not yet been clarified.

Morphological study on the regeneration of the retina in the rainbow trout after ouabain-induced damage: evidence for dedifferentiation of photoreceptors

The retina of the rainbow trout is capable of marginal regeneration after ouabain-induced degeneration (intraocular injection of 5 microliters 10(-4) M ouabain). In the central area where the pigment epithelium proliferates to a multicellular layer, the neural retina does not regenerate up to 182 days after injection of ouabain. The regeneration process begins in the marginal growth zone with an increase in the mitotic rate; the growth zone itself is not damaged after ouabain administration. The proliferate differentiates with time into a newly layered retina; this portion of the retina is called the paramarginal zone, i.e., the "first" regenerated zone. The paramarginal zone is arranged concentrically to the retinal margin. Cells surviving ouabain administration, located outside, although close to the margin and occurring mostly in the outer nuclear layer, reveal signs of dedifferentiation: loss of the outer segment, amalgamation of the presynaptic terminal with the perikaryal cytoplasm, alteration of cell shape, and mitotic activity. The area in which these dedifferentiation processes are observed is found adjacent and concentric to the paramarginal zone; it is thinner than the latter and incompletely structured ("second" regenerated zone). The third zone adjoins the second zone and is characterized by folds, which were described previously as "rosettes". Extracellular microtubule-like structures, which are found between the horizontal cells in the normal retina of the rainbow trout, regenerate only sparsely in the paramarginal zone, whereas they are lacking in the incompletely regenerated zones.

Myelination and remyelination in the regenerating visual system of the goldfish

The remyelination of regenerated optic axons was investigated in goldfish following either optic nerve crush or ouabain retinal intoxication. Axons grown after nerve crushing acquire thinner myelin sheaths than axons originating from reconstituted ganglion cells. If axons of reconstituted ganglion cells are crushed and allowed to regenerate, the subsequent myelination is weaker than that of control axons not interrupted by crushing, but stronger than that of axons of preexisting retinal ganglion cells. The present results suggest that a neuron is capable of inducing a normally developed myelin sheath when its axon contacts an oligodendrocyte the first time, whereas a neuron whose axon contacts an oligodendrocyte and the second time is not capable of forming a normal myelin sheath in the adult animal. The present results also support the notion that the oligodendrocyte requires a neuronal signal for myelin sheath formation.

Ionic shifts in myelinated nerve fibers during early stages of Wallerian degeneration

The distribution and relative mass fraction of the diffusible ions Na, K, Cl and Ca were determined by X-ray microanalysis in the axons of rat sciatic nerve 18 h and 36 h after crush and in control nerves. The investigations were performed in freeze-dried ultrathin cryosections after shock freezing of the nerves in liquified propane. 18 h after crush, no definite alteration of the ions were found compared to the control nerves. In electron micrographs of routinely processed nerves, no ultrastructural changes were seen. 36 h after crush, two types of ionic imbalance were found, the first characterized by decreased K and slightly increased Na in the axon, the second by concurrently increasing axonal Na and Cl, accompanied, in some fibers, by accumulating Ca. These types of ionic imbalance presumably represent two stages of axolemmal permeability alteration corresponding to early structural changes of axoplasm in electron micrographs of routinely processed nerves at that time.

Myelinated axons of ganglion cells in the retinae of teleosts

In the retina of the goldfish and the rainbow trout, the axons of ganglion cells belong to the unmyelinated or the myelinated types. The unmyelinated fibers are either arranged in bundles in direct contact with neighboring fibers or they are separated by intervening lamellae of oligodendroglial cytoplasm. The myelin sheaths of the myelinated fibers differ greatly in thickness. Most fibers show 3 to 5 myelin layers; single fiber elements, however, show 10 or even more layers.

Cryoultramicrotomy, electron probe microanalysis and STEM of myocardial tissue

Heart muscle preparations (papillary muscles and trabeculae) were frozen at 4.2 K on metal plate under vaccum after their length-tension relationships showed that no damage had occurred during dissecting and mounting the strips on the holder. Freeze substitution of some preparations directly after freezing demonstrated that no important cell damage due to ice crystals occurred in superficial cell layers during freezing. Ultrathin cryosections obtained at -130 degrees C were freeze dried and analyzed, in the STEM mode. The better the freezing procedure, the poorer was the contrast of the sections under electron microscopy. Preliminary approaches to increasing contrast after sublimation of tissue water show that a small increase in contrast is generally obtained at the cost of the peak/background ratio due to pronounced mass loss. The results of our analyses show that C1 content in heart muscle cells is high and distributed throughout the cytoplasm. Ca is detectable and quantitable in resting muscle in SR cisternae. The Ca amount in cytoplasm is low and just at the limit of detectability under our current analysis conditions. Preliminary experiments on papillary muscles subjected to caffeine contracture showed that calcium is not detectable in the cisternae as is the case in control experiments. Only a moderate amount of Ca is detectable in mitochondria, whereas the concentrations in cytoplasm, as in resting cardiac muscle, is too low to be quantitated.

Prospects of X-ray microanalysis in the study of pathophysiology of myocardial contraction

X-ray microanalysis was used to compare chemically untreated cryosections of quick-frozen myocardial tissue in "caffeine contracture" with cryosections of normal muscle. Our goal was to find out if it is possible by means of this method to detect changes in the calcium compartmentalization of the myocardial cell occurring by changes in its functional state. While it is possible to quantitate calcium in the cisternae of sarcoplasmic reticulum of the control muscle preparation, calcium could never be detected in these compartments of caffeine-contracted muscles. In active microsomal fraction of ventricular myocardium it is possible to quantitate calcium and also to distinguish two components on account of their different ability to accumulate this element. The calcium content is different in the two components of the fraction.

Electron probe X-ray microanalysis and cryoultramicrotomy of unstained myocardial sarcoplasmic reticulum, in situ and fragmented

Myocardial sarcoplasmic reticulum of cats in situ and fragmented sarcoplasmic reticulum (FSR) were analysed using X-ray microanalysis, cryoultramicrotomy and scanning transmission electron microscopy. 2 types of FSR vesicles can be distinguished morphologically and by their different elemental composition especially by different Ca loading. The Ca content of the sarcoplasmic reticulum can also be detected in situ.

Regeneration of the goldfish retina after exposure to different doses of ouabain

After ouabain-induced degeneration, the retina of the goldfish shows a remarkable regeneration capacity. The extent of the damage depends on the dose of ouabain used in the experiment. After intraocular injection of 7 microliter 10(-5) M ouabain, the ganglion cells and the cells of the inner nuclear layer (INL) become necrotic except for most of the outer horizontal cells, some bipolar cells, and Müller cells. The outer nuclear layer (ONL) and the marginal growth zone at the ora serrata remain intact; the plexiform layers become spongy. The degenerated material is removed by the proliferated reactive macroglial cells and invading macrophages. The degenerated cellular elements of the retina are replaced by mitosis of neuroblasts in the marginal growth zone and of cells in the ONL. After intraocular injection of a 5-fold higher dose of ouabain (7 microliter 5 . 10(-5) M), the degeneration of the retina proceeds more rapidly and completely. In this experiment, the ONL is destroyed and the receptor outer segments are phagocytosed by cells of the pigment epithelium. In contrast to the regeneration of the amphibian retina, in the goldfish cells of the pigment epithelium do not participate by metaplastic transformation in the regeneration of the retina. The only source of cellular regeneration of the retina after complete destruction of its differentiated neural elements is the marginal growth zone, which is highly resistant to ouabain. The rate of mitoses in this region is strongly increased. The derivatives of these cells spread out tangentially over the entire fundus of the eye in a concentric manner. In this regenerate, mitotic processes continue in a radial direction, resulting in thickening and layering of the new retinal formation.

Growth and myelination of goldfish optic nerve fibers after retina regeneration and nerve crush

Axonal regeneration in the optic nerve and tectum of the goldfish was studied both after retina regeneration and nerve crush. The retina regeneration was evoked by ouabain-induced damage of at least the ganglion cells and cells of the inner nuclear layer. The necrotic retinal neurons are substituted by mitotic processes in the outer nuclear layer and the marginal growth zone at the ora serrata. The axons of these newly developed retina ganglion cells grow through the degenerating, but mechanically undamaged, optic nerve into the tectum, establishing there synaptic contacts already 16 days after the intraocular ouabain-injection. The fibers were myelinated at first in the tectum, later on in the optic nerve. Thus, the myelination process proceeds in retrograde direction. About 60--80 days after injection the myelination has become nearly normalized. On the contra-lateral side of the same animal, the optic nerve was crushed near the eye-bulb. The axons of the original retina ganglion cells grow out into the degenerating optic nerve and tectum. They also find synaptic contacts and are myelinated in retrograde direction, but to a much lesser extent than the axons of the regenerated retina ganglion cells. An axonal factor is discussed, which would influence the oligodendroglial myelination activity. The effectiveness of this factor is probably dependent on the neuronal age and suggested to be triggered by the establishment of synaptic contacts.

Induction of paracrystalline arrays by vincristine in the synaptic formations of the teleost retina

After injection of 10 microliter 10(-3) M vincristine into the vitreous body of the eye of the rainbow trout (Salmo gairdneri, Richardson), paracrystalline arrays in cell bodies, cell processes and presynaptic formations of the retina cells were observed. The structures resemble the paracrystalline lattice identified by several authors as microtubular protein. The paracrystals in both microtubule-rich cell processes and in synaptic areas, which show only a few or no microtubules, appear to be equivalent. The synaptic paracrystals are suggested to arise from both soluble tubulin and synaptic vesicles, indicating a functional role of tubulin in synaptic transmission.

Extracellular microtubule-like structures in the retina of the rainbow trout: development, intercellular connectivity and reaction to vincristine

Extracellular microtubule-like structures (MLS) are described in the retina of the rainbow trout. They appear about 30 to 40 days after hatching, when the yolk-sac is consumed and the animal begins to swim and to nourish actively. They fill a widely branched system of extracellular clefts and spaces, and connect different cells and cell types, especially outer horizontal cells and bipolar cells. The MLS are not affected by the vinca alcaloid vincristine, although this drug penetrates into the MLS-filled space, as has been shown by the formation of intracellular, vincristine-induced tubulin paracrystals. The MLS are compared with other extracellular tubular structures described in other animal tissues. Their functional significance remains unclear.

[Small-nodular liver cirrhosis with marked portal hypertension due to vitamin A intoxication resulting from psoriasis treatment (author's transl)]

Clinical and histological signs of small nodular liver cirrhosis with portal hypertension were present in a 36-year-old man, three-and-a-half years after a seven-week course of treatment of psoriasis vulgaris with high doses of vitamin a (70 X 10(6) IU orally). Although there is no increase in serum level of vitamin A now, increased deposits of vitamin A in the perisinusoidal lipid storage cells (Ito cells) are still demonstrated by fluorescencespectrophotometry and under the electron microscope. Fundectomy with resection of the terminal oesophagus was necessary because of bleeding from oesophageal varices.

Microtubules and extracellular microtubule-like structures in the retina of the rainbow trout

In the retina of the rainbow trout (Salmo gairdneri, Richardson) two types of microtubular structures are demonstrated. Besides the normal type of microtubules (about 200 A in diameter), occurring in all cell types of the retina, a second type is described which is termed microtubule-like structure (MLS) because of its extracellular localization. These MLS have a diameter of about 250 A under the same preparative conditions in which the normal microtubules appear 180-200 A thick. The interspace between the tubules is smaller than between the microtubules. Specific MLS to membrane associations exist, which are analyzed by serial sectioning and tilting procedures. It is suggested that the MLS have their origin at small membranous extrusions of the plasmalemma. These extrusions could contain nucleation sites for the MLS-formation within the extracellular space. It remains unknown which cell type produces the MLS proteins and which factors are responsible for the aggregation of the subunits to intact MLS.

Evidence for the involvement of the Na+-K+-ATPase in the mechanism of axonal protein and nucleoside transport

[3H]Proline and [3H]uridine were injected into both eyes of the goldfish. 1 h before and after this injection 3X10)-6)M ouabain was administrated unilaterally to the retina. 8 h and 24 h after tracer injection the radioactivity in the retina, optic nerve and tectum was measured. It is suggested that the inhibition of the neuronal Na+-K+-ATPase inside the retina is responsible for the reduction of the labelled material transported into the optic nerve.

Influence of ouabain on the fine structure of teleost retina

In this study the effect of intraocular injection of 10 mul 10(-5) M ouabain on the retinal fine structure of the cyprinide teleost Carassius carassius is described. The final concentration of the drug in the eye-bulb was approximately 3-10(-6)M. After 8--24 h the ouabain application produces alterations in the retinal ganglion cells, that progress subsequently to necrobiosis. The outer horizontal cells of the inner nuclear layer show a severe cytoplasmic swelling that is reversible and disappears 8 days after ouabain injection. Amacrines, bipolars and receptor cells are relatively insensitive to the ouabain-induced Na+-K+-ATPase-inhibition. The differential susceptibility to ouabain in the retina possibly reflects a cell-specific pattern of Na+-K+-ATPase-activity or -concentration, whose physiological significance is discussed.

Time- and dose-dependent influence of ouabain on the ultrastructure of optic neurones

The cardiac glycoside ouabain was injected into the eye-bulb of the teleost fish, Carassius carassius. Three doses of ouabain were used: 10(-4) M, 10(-5) M, 10(-6) M. The final concentrations in the vitreous body of the eye were approximately 3-10(-5) M, 3-10-6 M and 3-10-7 M, respectively. After 8 hrs, 1, 2, 4, 6 and 8 days the ultrastructural alterations of retinal ganglion cells, the optic axons near the bulb and the terminal segments in the optic tectum were studied. The high doses of ouabain induced an early necrobiosis of the cell bodies in the retina followed by degeneration in the nerve. This is characterized as a protracted form of Wallerian degeneration. The significance of the inhibition of Na+ -K+-activated ATPase at the perikaryal level for both the integrity of axonal morphology and the axonal flow is discussed.