P. E. Spoerri

Accumulation of lipofuscin in the myocardium of senile guinea pigs: Dissolution and removal of lipofuscin following dimethylaminoethyl p-chlorophenoxyacetate administration. An electron microscopic study

Abstract Ultrastructural investigations of the left ventricular myocardium of senile guinea pigs revealed marked accumulation of lipofuscin pigment. Dimethylaminoethyl p-chlorophenoxyacetate administration (daily 80 mg/kg of body weight i.m.) to guinea pigs for 30–90 days, caused dissolution as well as marked reduction in the size of the pigment. Pigment residuals were carried by phagocytic cells to the capillary wall and discharged into the lumen. These pigment alterations and their mode of transport were not found in the control group of guinea pigs.

The effects of dimethylaminoethyl p-chlorophenoxyacetate on spinal ganglia neurons and satellite cells in culture. Mitochondrial changes in the aging neurons. An electron microscope study.

Abstract The formation and distribution of old age pigment in neurons and satellite cells of spinal ganglia in culture were studied electronmicroscopically, following daily application of the cultures, for 2–3 weeks, with dimethylaminoethyl p -chlorophenoxyacetate and compared with cultures of the same age. The relationship of the aging pigment to the mitochondria has been re-investigated. In the EM sections a fading out as well as conspicuous vacuolation of the pigment could be observed at the beginning of drug application. This was followed by disintegration and replacement of the pigment by fine osmiophilic granules leading to a diminution in the total amount of pigment present. Cytoplasmic processes and satellite cells transported the pigment to the interneural space. Further removal of the pigment occurred by means of phagocytes and proliferating endothelial cells of residual capillaries. The possible mitochondrial genesis of age pigment is discussed.

Dissolution and removal of neuronal lipofuscin following dimethylaminoethyl p-chlorophenoxyacetate administration to guinea pigs

SummaryDimethylaminoethyl p-chlorophenoxy acetate (80 mg/kg body weight) was administered (i. m.) to guinea pigs for 30 to 56 days. Electron microscopic examination of the hippocampus, mid-brain reticular formation and the area postrema revealed marked diminution in the electron density of the pigment granules and vacuolization. This type of lipofuscin was detected in some phagocytic cells and in the capillary endothelium. Conspicuous vacuolization of the capillary wall was discernible. These changes were not observed in the “control group” of animals.

GABA or sodium-bromide-induced plasticity of neurites of mouse neuroblastoma cells in culture

SummaryDifferentiated C1300 mose neuroblastoma cells were treated with 10−4−106 M γ-aminobutyric acid (GABA) and/or sodium bromide (NaBr) for 2 days and then fixed. Quantitative studies revealed an increase in the length and branching of the processes, as well as an increase in the number of cells when compared to the controls.It is suggested that the above changes contribute to the augmentation of specialized contacts between cells and processes as well as the further maturation of the primitive stages of synaptogenesis as discussed.

Morphological changes induced by sodium bromide in murine neuroblastoma cells in vitro

SummarySodium bromide was applied in vitro to mouse neuroblastoma cells of different ages for short and long periods (2h to 10 days). The changes observed light-and-electron microscopically were similar to those described earlier after GABA treatment. Coated vesicles proliferated and originated by pinching off from the Golgi complex and from the rough endoplasmic reticulum. Numerous coated vesicles were continuous with the plasma membrane, especially near zones in which electron-dense material aggregated at the inner aspect of the plasmalemma. Small invaginations, similar in ultrastructure to coated vesicles, were also formed. It is unclear whether the coated vesicles or the dense plasmalemma invaginations contribute to the “undercoating” by fusing with the adjacent electron-dense plasma membrane. There was a distinct increase in the number and area of specialized contacts (intermediate junctions and zonulae adhaerentes) between cells and their processes. A floccular or filamentous electron-dense substance varying in amount and appearance was occasionally seen between the contacting membranes. Varicosities of terminal swellings of cell processes contained vesicles of variable size, shape and density, and also profiles of the smooth endoplasmic reticulum. Under the influence of sodium bromide, similar to the effect of GABA, mitochondria appeared within the varicosities, and primitive contacts (intermediate junctions) were formed between the terminal swellings and potential postsynaptic elements, which were absent in controls.Additionally, dense-core vesicles proliferated and aggregated at the cell periphery. They were often arranged linearly below the plasma membranes of perikarya and processes, and surrounded by a highly electron-dense substance. The similarity of the present findings to those obtained after GABA treatment and their relation to synaptogenesis are discussed.

The time course of synapse formation of mouse neuroblastoma cells in monolayer cultures

SummaryNeuroblastoma cells grown on substrates in culture develop long processes and assume the morphology of normal neurons as judged light microscopically. The development of synapses in the cultured tissue is studied by periodic electron microscopic examination of the areas of contact between cells. The initial expiants are free of any apparent synaptic contacts. After 48 h in culture, simple swellings or boutons are detected at the periphery of the cells or at the end of the fine processes. These initial synaptic profiles contain a few vesicles but lack mitochondria. The synaptic vesicles appear to originate from the smooth endoplasmic reticulum. Further expiants remain primitive, only the number of vesicles in the cytoplasmic swellings or boutons increases. These clusters of vesicles are 40–60 nm in diameter and morphologically distinguishable from the synaptic vesicles of normal neurons. There are no postsynaptic folds or membrane thickenings. Specialized cell contacts between cells are also present.

Subsurface cisterns in the Cynomolgus retina

SummarySubsurface cisterns were found in retinal neurons of the Cynomolgus monkey. They were located in amacrine, bipolar and ganglion cells and were associated with the rough endoplasmic reticulum. Subsurface cisterns were not found in Müller cells. The possible functional significance of the subsurface cisterns is discussed.

Surface processes of olfactory receptors

SummaryThe free surface morphology of olfactory receptor cells from the nasal mucosa of Cynomolgus monkeys was studied electron microscopically. The receptor cell, in addition to showing characteristic cilia, possesses several branched or unbranched shorter elevations or spiny processes covered by numerous delicate lace-like filaments not previously described. These filaments diminish in length and number toward the base of the microvillous protrusions.

Annulate lamellae, lamellar bodies and subsurface cisternae in neurons of the avian hyperstriatum accessorium

SummaryStructures identified as annulate lamellae, lamellar bodies and subsurface cisternae were found in neurons of the hyperstriatum accessorium of the avian forebrain. Annulate lamellar arrays with up to six lamellae were present in the larger somata. The lamellae were made up of fused smooth-surfaced cisternae forming pores or annuli and were surrounded by a dense filamentous to granular material. Stacks of nonfenestrated, parallel, regularly spaced cisternae, designated as lamellar bodies, also appeared in the cytoplasm. When flattened they were reminiscent of the electron dense subsurface cisternae. Continuity could be demonstrated between peripherally located subsurface cisternae and lamellar bodies. The dense filamentous to finely granular substance was also located between these structures. Annulate lamellae, lamellar bodies and subsurface cisternae were always observed in conjunction with the rough endoplasmic reticulum. The functional significance of these structural associations is considered.

Ultrastructural reactions of spinal ganglia to tri-ortho-cresyl-phosphate: effects of neurotoxicity.

SummaryThe ultrastructure of neurons in spinal ganglia of the domestic fowl poisoned with tri-ortho-cresyl-phosphate (TOCP) shows characteristic changes. The light neurons react to TOCP by a marked increase in the number of neurofilaments. These neurons also contain mitochondria in various degenerative stages. Several of the altered mitochondria show an increasing osmiophilia. Some of the darker neurons display a hypertrophy of the endoplasmic reticulum or a relative increase of neurofilaments. The mitochondria in some of these cells show early stages of degeneration. These changes appear 13 days after TOCP ingestion.