Ultrastructure of Octodon degus spermatozoon with special reference to the acrosome

The ultrastructure of spermatozoa from the cauda epididymidis and vas deferens of Octodon degus — a Chilean hystricomorph rodent—is presented. The head of spermatozoa measured 7.7 μm long by 5.9 μm wide and the tail was 41 μm long. The head was flattened dorso-ventrally and ovate in outline. The acrosome was the most distinctive feature of O. degus spermatozoa. In a frontal view of the head, the rim of the acrosome surrounding the nucleus had the shape of an inverted U. The acrosomal region covering the plane of the flattened head exhibited dome-shaped protrusions. Transverse or sagittal sections of acrosomal protrusions showed that the plasma membrane and outer acrosomal membrane were evaginated, while the inner acrosomal membrane followed the contour of the nucleus. The protrusions were not distributed at random and they were absent in the equatorial segment and in the rim of the acrosome. In frontal views, near the boundary between the acrosome and post-acrosomal region, fine rods about 170 nm long ran obliquely on the caudal part of the equatorial segment. Behind the same boundary, the post-acrosomal region showed a serrated border. Phosphotungstic acid treatment at pH 0.3 produced staining at the surface of the sperm as well as within a superficial layer of the marginal thickening of the acrosome and on the acrosomal protuberances.     

Hyaluronan in the rat with special reference to the skin

The total hyaluronan content has been determined in rats. The animals were frozen and sectioned in a cryostat before digestion with papain and pronase. The hyaluronan content was determined by a specific radioassay and it was found that 250 g rats contained 40-60 mg of the polysaccharide. The recovery from the preparation procedure was close to 100%, as determined from tracer experiments. More than half of the hyaluronan was found in skin, approximately one quarter in the skeleton and supporting structures and less than one tenth in skeletal muscle. Based on calculated lymph flow and lymph concentration of hyaluronan, it seems that a significant fraction of the total hyaluronan in skin (greater than 1%) is removed via the lymphatics in a 24 h period. An attempt was made to isolate undegraded hyaluronan from rat skin by gentle methods giving full recovery in order to estimate the molecular weight of the polysaccharide. Hyaluronan was recovered quantitatively, but as determined from added tracer, it had been degraded. Correction for the estimated degradation gave a molecular weight of several millions for the endogenous hyaluronan.     

Ultrastructure of well-differentiated adenocarcinomas of the lung with special reference to bronchioloalveolar carcinoma

The cytologic phenotypes of 20 well-differentiated pulmonary adenocarcinomas were determined by electron microscopy. On examination of more than 100 cells in each case, the tumors were classified according to the predominant cell types. Nine cases (45%) were of mucous cell type, further divided into 7 cases of bronchial surface epithelial cell type, 1 case of bronchial gland cell type, and 1 case of metaplastic bronchiolar goblet cell type. The remainder included 5 cases (25%) of Clara cell type, 2 cases (10%) of type II cell type, and 4 cases (20%) of mixed cell type. The predominant histologic pattern by light microscopy was "typically" bronchioloalveolar (Manning et al.'s type 1) in the metaplastic goblet cell tumor and papillary in most Clara cell-type tumors, while it was glandular in bronchial surface and bronchial gland cell types, although variable in type II cell or mixed cell type. Therefore, bronchioloalveolar carcinomas, when histologically defined inclusive of papillary tumors, present cytologic phenotypes also related to the bronchioloalveolar epithelium, i.e., metaplastic goblet or Clara or type II cell subtypes, which is in accordance with some previous reports. These tumors could be distinguished from the other (glandular) adenocarcinomas that show primarily bronchial mucous cell differentiation.     

Ultrastructure of the ovarian germ cells in the quail embryos, with special reference to the oocytes

Developing germ cells from oogonia to oocyte stages in embryonic quail ovaries were observed ultrastructurally. In contrast with those of chicks, quail oocytes showed some conspicuous structures. Typical feature of the Balbiani body, which was constructed by eccentrical concentration of whole organelles, was observed through the oocyte stage, although loose aggregations of organelles were found even at the oogonial stage. Such striking feature of Balbiani body was not observed as yet in any animal species. Golgi apparatus, which occupied the center of a Balbiani body, was often found attaching with the nuclear membrane. This finding suggests that the Balbiani body play some role for the oocyte maturation. Upon the nuclear membrane of oocytes, a great number of electron dense structures were found. They were thought to be a kind of nuclear pore complexes. Such abundance of the nuclear pore complexes was another structural characteristic of quail oocytes. They increased in number according to the progress of embryonic development, although small numbers were also seen even at the oogonial stage.     

Ultrastructure of the spleens in childhood ITP with special reference to the foamy cells

We examined the spleens from four patients with childhood ITP. Numerous foamy cells were investigated in two cases, moderate number in one case, and a few in one case. PAP method using anti-human platelet antibody demonstrated the platelet antigen in the cytoplasms of these foamy cells, which were granular or reticular. Electron microscopically, many platelets in various stages of intracellular digestion from intact-appearing forms to myelin-like materials, were disclosed. Enzyme cytochemical electron microscopy revealed localization of acid phosphatase activity around the degrading platelets and vacuolated inclusions, but rarely in the myelin-like materials. We suggest that the mechanism of formation of the foamy cells in ITP is as follows; macrophages phagocytize many platelets, exhaust their lysosomal enzyme, and can not digest the engulfed platelets completely. Thus the partially degraded platelets remain as myelin-like materials in the cytoplasm of macrophages, which have foamy appearance in light microscopy.     

Some observations on the fine structure of the epidermal-dermal junction in the skin of the frog tadpole,Rana rugosa

Special lamellated bodies, 400 to 700 Å in diameter, are observed in the adepidermal space at the epidermal-dermal junction of the skin of the frog tadpole, Rana rugosa. Each stained lamella is about 20 Å thick and separated from adjacent lamellae by spacings of 20 to 30 Å. The lamellated bodies are demonstrated in specimens prepared with phosphotungstic acid (PTA)-containing fixatives, but are not revealed in specimens fixed with ordinary aldehyde fixatives which lack PTA. They are sometimes observed within the cytoplasm of basal epidermal cells, suggesting their epidermal origin. Far less frequently, comparable structures are present outside the sarcolemma of skeletal muscle fibers. Three kinds of anchoring structures are observed at the epidermal-dermal junction: anchoring filaments, anchoring fibrils, and anchoring fibers. The anchoring filaments are observed in the adepidermal space connecting hemidesmosomes to the basal lamina. They are 200 to 230 Å in diameter and have no banding pattern. Anchoring fibrils, 210 to 250 Å thick and unbanded, are present in the upper one-third of the collagenous lamellae. Fibrils do not have a banding pattern. Direct continuity between anchoring fibrils and anchoring filaments is suggested. Anchoring fibers, about 170 mμ, thick, occur less frequently. They are composed of laterally aggregated finer fibrils which show no clear bandings. Their distal ends join with the basal lamina and they extend proximally deep into the collagenous lamellae.     

Oxidative and nitrative DNA damage as biomarker for carcinogenesis with special reference to inflammation

Reactive oxygen and nitrogen species are known to participate in a wide variety of human diseases. Oxidative DNAdamage is involved in chemical carcinogenesis and aging. Monocyclic chemicals induce mainly oxidative DNAdamage, whereas polycyclic chemicals can induce oxidative DNA damage in addition to DNA adduct formation. Recently, chronic infection and inflammation have been recognized as important factors for carcinogenesis. Nitrative DNA damage as well as oxidative DNA damage is induced in relation to inflammationrelated carcinogenesis. The authors examined the formation of 8-nitroguanine, a nitrative DNA lesion, in humans and animals under inflammatory conditions. An immunofluorescence labeling study demonstrated that 8-nitroguanine was strongly formed in gastric gland epithelial cells in gastritis patients with H. pylori infection, in hepatocytes in patients with hepatitis C, and in oral epithelium of patients with oral lichen planus. 8-Nitroguanine was also formed in colonic epithelial cells of model mice of inflammatory bowel diseases and patients with ulcerative colitis. Interestingly, 8-nitroguanine was formed at the sites of carcinogenesis regardless of etiology. Therefore, 8-nitroguanine could be used as a potential biomarker to evaluate the risk of inflammation- related carcinogenesis.     

Microvasculature of the mouse epididymis, with special reference to fenestrated capillaries localized in the initial segment

The blood supply, microvasculature, and ultrastructure of the capillaries in the epididymis in adult mice were regionally examined. The epididymal duct of the initial segment is surrounded with a dense network of fenestrated capillaries running just under the epithelium. The other segments have loose networks of nonfenestrated capillaries running in the interductal connective tissue. The fenestration of capillaries in the initial segment was markedly reduced in frequency immediately after cutting the efferent duct. In adult mice which were subjected to cutting of the efferent duct neonatally, the dense capillary network did not develop, and fenestrated capillaries were absent in the initial segment. We interpret our results to indicate that the fenestrated capillaries in the initial segment provide for absorption of the testicular fluid and that their development is dependent upon the testicular fluid entering the epididymal duct.     

Ileocecal junction: anatomic, histologic, radiologic and endoscopic studies with special reference to its antireflux mechanism

Aim  

The aim of the study was to perform histomorphologic, endoscopic, and radiologic studies of the ileocecal junction (ICJ). A clearer understanding of the anatomical structure of the ICJ may shed some light on its function.