Evaluation of a completely automated tissue-sectioning machine for paraffin blocks

Tissue-sectioning automation can be a resourceful tool in processing anatomical pathology specimens. The advantages of an automated system compared with traditional manual sectioning are the invariable thickness, uniform orientation and fewer tissue-sectioning artefacts. This short report presents the design of an automated tissue-sectioning device and compares the sectioned specimens with normal manual tissue sectioning performed by an experienced histology technician. The automated system was easy to use, safe and the sectioned material showed acceptable quality with well-preserved morphology and tissue antigenicity. It is expected that the turnaround time will be improved in the near future.

Callinera emiliae sp. nov. (Nemertea: Palaeonemertea) from Negros Island, the Philippines

Callinera emiliae sp. nov., the ninth member of the genus, is described based on three specimens collected in Dumaguete, Negros Island, Republic of the Philippines. The new species can be distinguished from its congeners by the following characteristics: lateral sensory organs present; sub-epidermal glandular cells absent; blood vascular system without a ventral cephalic connective; nervous system with two dorsal cerebral commissures; and foregut nerves fused to form a ganglion in front of the mouth. In living specimens, epidermal constrictions were observed in the intestinal region; the presence of intestinal sphincters was confirmed in sectioned material and these correspond with the epidermal constrictions.

Immuno- and affinity probes for electron microscopy: a review of labeling and preparation techniques.

Immuno- and affinity probes are widely used in biology and medicine, and are becoming essential tools for the elucidation of cell structure and function. This article reviews and discusses the bewildering array of probes and preparation techniques now available for the investigation of sectioned material by transmission electron microscopy, with critical analysis of their merits. Emphasis is placed on immunogold probes and methods useful for routine preparation, gathering together information that may be used to improve labeling techniques. New data on inert dehydration for the localization of sensitive epitopes without chemical or cryofixation is presented.

Cytochemistry and ultrastructure of the dehiscence zone of almond (Prunus dulcis) fruits

At maturity, the almond pericarp dehisces along the ventral suture, a region that originates by fusion of epidermal cells and subsequently differentiates into a separation layer. We have characterized the ontogeny of the fusion–dehiscence zone with emphasis on cell wall characteristics by using cytochemical methods for detection of pectin, cutin, cellulose, and lignin to examine the middle lamellae and primary and secondary walls in dehiscence-zone cells. Carpel margins became united postgenitally along opposing epidermal layers giving rise to the suture. Fusion-zone cells host epidermal characteristics, elaborated broad pectinaceous walls, and ultimately formed a discrete band of cells that dehisced along the original line of fusion by dissolution of cell wall pectins. Treatment of treeborne fruits with 1 ppm ethylene gas or extraction of sectioned material with cell wall hydrolases resulted in cell wall changes similar to those in predehiscent fruits.

Coronavirus?

To the Editor.— We read with great interest the paper by Rousset et al1 in which the presence of coronavirus-like particles in intestinal lesions of neonates with necrotizing enterocolitis was described. The presence of viral particles in thin-sectioned material is often difficult to demonstrate because of the striking similarity of some viral particles to normal cell organelles and structures. We agree with the authors that coronavirus-like particles may be an etiologic agent in some cases of neonatal necrotizing enterocolitis of nonbacterial origin2,3; we do not agree, however, that their published electron micrographs unequivocally demonstrate viral particles.

Morphological examination of cell surface structures of enterotoxigenic strains of Escherichia coli

The very fine sinuous K99 pili of enterotoxigenic strains of Escherichia coli can be visualized in shadowed and in negatively stained preparations, especially if the amorphous K30 glycocalyx is not produced, but these very delicate structures cannot be directly resolved in sectioned material. The K99 pili can, however, be thickened by the nonspecific accretion of K30 glycocalyx material, during its condensation as a result of dehydration, to the point where it can be resolved in sectioned material. This visualization is enhanced if the accreted and condensed glycocalyx is stained with ruthenium red. Alternatively and additionally, the K99 pilus can be thickened by the specific accretion of monoclonal antibodies so that it is made visible in sectioned material. The condensation of the hydrated K30 antigen glycocalyx of enterotoxigenic strains of Escherichia coli during dehydration can be prevented by stabilization using specific antibodies so that this capsular glycocalyx structure is identified in sectioned material and is seen in its correct distribution and dimensions. These methods allow the identification and visualization of bacterial surface structures, both in vitro and in vivo, and they provide a useful means of assessing the presence and distribution of these structures at all stages of the bacterial disease and a possible means of assessing their roles in the pathogenic process.