J. J. Vázquez

Malignant struma ovarii: Light and electron microscopic study

Malignant struma ovarii is a very rare tumor, consisting of a struma ovarii with malignant change. Only 17 examples with metastases have previously been reported. We present a case which involved both ovaries and produced multiple metastases. Microscopy and ultrastructure were identical to a mixed papillary and follicular carcinoma of the thyroid gland. Characteristic ultrastructural features of malignant struma ovarii are: microvilli on the surface and in the cytoplasmatic vacuoles; oncocytic transformation of cytoplasm of some cells; and presence of electron dense, granular and crystalline material (colloid) in the follicles and vacuoles. The patients thyroid was normal. We conclude that malignant struma ovarii can only be diagnosed when a carcinoma arising in the thyroid gland can be excluded. Ultrastructure examination may provide useful diagnostic features separating malignant struma ovarii from strumal carcinoid and serous adenocarcinoma.

A comparative ultrastructural study of chondrosarcoma, chordoid sarcoma, and chordoma.

A morphologic and electron microscopic study was made of two chordoid sarcomas. These lesions were compared with two classical chondrosarcomas and two chordomas. The chondrosarcoma cells showed many features common to chondrocytes, such as abundant RER, well‐developed Golgi complexes, and microvillous cytoplasmatic membranes. The chordoid sarcomas bore a close morphologic resemblance to the chordomas but the ultrastructural features revealed a close relationship to the chondrosarcomas. The chordoid sarcoma and chondrosarcoma cells had scalloped cytoplasmatic membranes, variable amounts of glycogen, round or oval nuclei and microfibrils, collagen, and electron‐dense granules in the ground substance. The chordoma was characterized by the presence of stellate and physalipherous cells, as well as many transitional cells, with varying nuclear morphology; dilated and irregular RER in contact with mitochondria and morphologically varied vacuoles are the main features in the cytoplasm. This study suggests that chordoid sarcoma represents a variety of the chondrosarcoma rather than a form of chordoma. These findings also support the suggestion of Weiss that chordoid sarcoma is an extraskeletal myxoid chondrosarcoma.

Ultrastructure and immunocytochemistry of endocrine cells in the midgut of the desert locust, Schistocerca gregaria (Forskal)

SummaryThe endocrine cells of the midgut epithelium of the desert locust are found dispersed among the digestive cells and are similar to those of the vertebrate gut. According to their reactivity to silver impregnation techniques and the ultrastructural features of the secretory granules (shape, electron-density, size, and structure) 10 types of endocrine cell have been identified, of which seven are located in the main segment of the midgut or in the enteric caeca, and the other three seem to be present only in the ampullae through which the Malpighian tubules drain into the gut. The endocrine cells have a slender cytoplasmic process that reaches the gut lumen, a feature that supports the receptosecretory nature postulated for this cellular type in insects as well as vertebrates. Antisera directed against mammalian gastrin, CCK, insulin, pancreatic polypeptide and bombesin reacted with some of the endocrine cells. This is the first time that insulin- and bombesin-like immunoreactive cells have been described in the midgut of an insect.

Lymphangiomyomatosis. Morphogenetic study and ultrastructural confirmation of the histogenesis of the lung lesion

A 34‐year old woman underwent a surgical intervention as a result of a retroperitoneal tumor. This tumor was excised and the pathological diagnosis was lymphangiomyoma. Two months later she developed a spontaneous right pneumothorax with a chylous pleural effusion. Roentgenograms showed that the lungs had developed a honeycomb pattern. She was treated surgically and at the same time a biopsy was performed. Sixteen months later she developed a left pneumothorax which necessitated additional surgery, and a further biopsy was taken. She died of respiratory insufficiency 2 years after the clinical onset of the symptoms. The pathologic material was studied by both electron and light microscopy in serial sections. The electron‐microscopic study proved the muscular nature of this condition. The light microscopic study of the serial sections showed that the lung lesion was due to the proliferation of the muscle cells associated with the lymphatics surrounding the acini.

Angiostrongyliasis in a European patient: a rare cause of gangrenous ischemic enterocolitis.

Angiostrongylus costaricensis causes a clinicopathologic disease first observed in Costa Rica, mainly in children characterized by highly symptomatic eosinophilic gastroenteritis involving the terminal ileum, cecum, appendix, and ascending colon. A case of angiostrongyliasis in an adult Spaniard infected during a brief stay in Nicaragua is reported. We examined the macro-microscopic features of a right ileocolic resection of a 52-year-old patient. In the surgical specimen, multiple confluent ulcers, some perforated, were observed particularly in the terminal ileum. The intestinal wall was thickened, and the arterial branches presented necrotizing arteritis with thrombosis and a heavy infiltrate of eosinophils around the vessels. In addition, some granulomas were observed. Adult male and female forms of A. costaricensis were found in the lumen of many arterial branches and in the tissue of the omentum, surrounded by dense eosinophilic infiltrate. A. costaricensis causes an intense eosinophilic, necrotizing arteritis associated with thrombosis leading to severe ischemic lesions. This is the first case to be diagnosed in Europe. Incubation time was able to be established within a period of at least 14 days.

Histological and immunocytochemical study of the endocrine pancreas of the lizard Podarcis hispanica steindachner, 1870 (lacertidae)

The endocrine pancreas of the lizard Podarcis hispanica is described using light and electron microscopy. The endocrine pancreas of this reptile is located throughout the spleen side of the organ and consists of islet-like structures, small groups of two to five cells, and single scattered endocrine cells. The endocrine cells, including the islet-like structures, are not discrete units; on the contrary, they are intermingled with the endocrine component, both forming the glandular units. The endocrine islet-like structure shows a peculiar pseudoacinar pattern. The tridimensional reconstruction allows us to recognize the true structure of the glandular units. They are made up of two or three tubules closely arranged around a blood vessel, the endocrine component being disposed in the facing aspects of the tubules, around the vessel. Silver methods, Giemsa, and peroxidase-antiperoxidase techniques for light microscopy, immunogold, and routine methods for electron microscopy were used to demonstrate the regulatory peptide-producing cells present in the endocrine pancreas. Four major pancreatic endocrine cells, immunolocalized with the light and electron microscope, have been described: glucagon-containing cells (granules of 440 nm in diameter), insulin cells (400 nm), somatostatin cells (610 nm), and pancreatic polypeptide-containing cells (460 nm).

Gut endocrine cells in the snail Helix aspersa

A microscopic study of the endocrine cells present in the gut of the snail Helix aspersa is made. Electron microscopy is necessary in most cases to identify the enteroendocrine cells, since neither silver impregnations nor immunocytochemical staining have rendered positive results. Endocrine cells are scarce and rest on the basement membrane. They display a clear cytoplasm and variable amounts of small (143 nm) secretory granules of diverse electron-density. They are ovoid or rounded and possess apical processes which extend into the lumen of the gut. The nucleus, located in the basal region of the cell, presents characteristic cytoplasmic indentations. Intraepithelial nerve bundles in contact with endocrine cells are present.

Development of the endocrine pancreas during larval phases of Rana temporaria

SummaryThe pancreatic endocrine component was studied at different stages of development in the tadpoles of Rana temporaria. The material was embedded in Epon, and serial semithin and thin sections were made in order to correlate ultrastructural features and tinctorial traits of the endocrine cells. Serial semithin sections were also stained with the peroxidase-antiperoxidase immunocytochemical method and with silver impregnations for argyrophilia and argentaffinity. In early larvae (legless tadpoles), A and B cells are present. Both can be found within ducts and exocrine tissue or, more frequently, in cellular clusters among the ducts and acini. These primitive islets are solid structures, surrounded but not penetrated by capillaries. Mitoses were observed in A and B cells. In the following phase (tadpoles with hindlegs), D and pancreatic polypeptide-immunoreactive cells are also present, as well as numerous endocrine cells scattered among exocrine tissue. There is also a change in the vascular-insular pattern: capillaries not only surround but also penetrate the endocrine group. The structure of the endocrine pancreas in older tadpoles is similar. Tinctorial traits and ultrastructural features of endocrine cells are described, and the origin of primitive islets is discussed.

Giemsa stain applied to deplasticized sections to identify pancreatic islet cells.

A new application of the Giemsa stain to demonstrate endocrine cells in deplasticized sections of Epon embedded material is described. Its application to the pancreas of Rana temporaria is illustrated. The technique does not require postfixation with OsO4 and is easily performed in 30 min. It allows the easy identification of three types of endocrine cells (A, B, and D). A cells, preferentially located at the islet periphery, stain purple-blue. B cells, which occupy the interior of the islet, display a lilac color. D cells give a strong purple color; they are located both in the periphery of the islets and scattered among acinar cells. Positive identification of the cell types was made by immunocytochemistry and electron microscopy.

Localization of G cells in the antral mucosa of Rana temporaria: Immunocytochemical and electron microscopy study

G cells of the frog antral mucosa are described both in deplasticized semithin sections treated with antigastrin/CCK COOH terminal serum and in subsequent thin sections observed under the electron microscope. G cells are quite abundant in the antral mucosa, located between mucosecretory cells in the lateral aspects of glands. They bear irregular, occasionally round granules, with a 190-nm mean diameter.