As You Like It, Part 2: A critique and historical review of the electron microscopy literature

Ribosome-lamella complexes in injured podocytes: description of a case and review of the literature

Ribosome-lamella complexes (RLCs) are mainly observed in a variety of hematological disorders and occasionally in solid neoplasms and in nonneoplastic diseases. These intracytoplasmic organelles are held to arise from rough endoplasmic reticulum, but, in agreement with more recent literature data, their function is still unclear. Ultrastructural analysis of glomeruli from a patient with focal segmental glomerulosclerosis secondary to metabolic syndrome disclosed significant foot process loss and abundant cytoskeletal proteins in major podocyte processes; two of the latter also displayed RLCs. This is the second report of RLCs in human renal glomerulus. Their close association with cytoskeletal proteins and lysosomes suggests a relationship with abnormal protein biosynthesis.

Arrangement and fine structure of collagen fibrils in the decidualized mouse endometrium

The adaptations of the mouse uterus to pregnancy include extensive modifications of the cells and extracellular matrix of the endometrial connective tissue that surround the embryos. Around each implanted embryo this tissue redifferentiates into a transient structure called decidua, which is formed by polygonal cells joined by intercellular junctions. In the mouse, thick collagen fibrils with irregular profile appear in decidualized areas of the endometrium but not in the nondecidualized stroma and interimplantation sites. The fine organization of these thick fibrils has not yet been established. This work was addressed to understand the arrangement and fine structure of collagen fibrils of the decidua of pregnant mice during the periimplantation stage. Major modifications occurred in collagen fibrils that surrounded decidual cells: (1) the fibrils, which were arranged in parallel bundles in nonpregnant animals, became organized as baskets around decidual cells; (2) very thick collagen fibrils with very irregular profiles appeared around decidual cells. Analysis of replicas and serial sections suggests that the thick collagen fibrils form by the lateral aggregation of thinner fibrils to a central fibril resulting in very irregular profile observed in cross sections of thick fibrils. The sum of modifications of the collagen fibrils seem to represent an adaptation of the endometrium to better support the decidual cells while they hold the embryos during the beginning of their development. The deposition of thick collagen fibrils in the decidua may contribute to form a barrier that impedes leukocyte migration within the decidua, preventing immunological rejection of genetically dissimilar embryonic tissues.

Soft tissue sacrococcygeal chordoma with intracytoplasmic filamentous inclusions

Extraskeletal chordoma arising within soft tissue is a rare occurrence. We report a case of chordoma that is unusual both for its location within the subcutaneous soft tissue of the sacrococcygeal region without involvement of adjacent bones and for the presence of eosinophilic roundish inclusion bodies within the cytoplasm of tumor cells. These bodies revealed immunoreactivity for cytokeratin and a fibrillar, partly whorled structure on the electron microscopic examination, consistent with an intermediate filament-based composition. To our knowledge, this is the first report of chordoma featuring this cellular change although we do not know the significance of these bodies.

Ultrastructural alterations of the hepatopancreas in Porcellio scaber under stress

Cellular ultrastructure varies in accordance with physiological processes, also reflecting responses to environmental stress factors. Ultrastructural changes of the hepatopancreatic cells in the terrestrial isopod Porcellio scaber exposed to sublethal concentrations of zinc or cadmium in their food were identified by transmission electron microscopy. The exclusive structural characteristic of the hepatopancreas of animals exposed to metal-dosed food was grain-like electrondense deposits (EDD) observed in the intercellular spaces and in vesicles of B cells. In addition, hepatopancreatic cells of metal-exposed animals displayed non-specific, stress-indicating alterations such as cellular disintegration, the reduction of energetic reserves (lipid droplets, glycogen), electron dense cytoplasm, ultrastructural alterations of granular endoplasmic reticulum (GER), the Golgi complex and mitochondria.

Hyalinising spindle cell tumour with giant rosettes: report of a case with unusual features including original histological and ultrastructural observations

Hyalinising spindle cell tumour with giant rosettes (HSCTGR) is an uncommon, recently described low-grade sarcoma which shares many histological features with low-grade fibromyxoid sarcoma (LGFMS). We report a case of HSCTGR occurring in the deep soft tissues of the thigh of a 46-year-old woman, that presented as a slowly growing, painless mass. Microscopically the tumour was composed of spindled stromal cells amongst which were scattered so-called collagen rosettes. The distinctive feature of this case was the previously unreported finding of lymphoid cells of T-cell phenotype admixed with fibrohistioctyic cells in the cellular cuff surrounding the collagenous core of the rosettes. The case was further unusual in that it included focal areas of increased cellularity with a mitotic count of up to three per 10 high-power fields. While the latter feature has been associated with increased recurrences and metastases in LGFMS, it is not known whether the significance is similar in HSCTGR. The spindled stromal cells showed ultrastructural features of poorly differentiated fibroblasts, while those at the edges of the rosettes showed features of altered fibroblasts, some with a fibrohistiocytic appearance. These findings support the interpretation that HSCTGR forms part of the spectrum of sarcomas showing fibroblastic differentiation.