Müller cells and diabetic retinopathy.

Müller cells provide nutrition for neural cells. We studied the structure and ultrastructure of Müller cells in the retina of thirty 3-month old Wistar rats, divided equally into 3 groups: normal rats, alloxan diabetic rats and treated alloxan diabetic rats, 1 and 12 months after induction of diabetes. We observed that the Müller cell nuclei under light microscope examination had hexagonal shape and higher density than the other nuclei. Differences between groups could be observed only by electron microscopy. In the diabetic rats, Müller cells presented dispersion of nuclear chromatin and electrondense nuclear granulations, with the presence of increased glycogen, dense bodies and lysosomes in the cytoplasm. The alterations were more frequent in the perivascular region and at 12 months. The treated diabetic rats exhibited some alterations we observed in diabetic rats, but these alterations were less intense. We conclude that, despite the treatment, the diabetic retinopathy continues to evolve.

Gap junctions between mast cells and fibroblasts in the developing avian eye

Mast cells are present in the eye of chick embryos from the 14th day onward, displaying metachromatic granules, mainly in the iris anterior surface and pectinate ligament. Ultrastructurally these cells show electron-dense granules and a few thin and short cytoplasmic projections in close contact with fibroblasts. Sometimes these contacts are extensive, with long fibroblast projections partially involving the mast cells. Gap junctions between mast cells and fibroblasts are observed only in the eyes of 16- and 20-day-old embryos. These intercellular specializations are represented by a close apposition of cytoplasmic membranes with an extension up to 300 nm. Gap junctions between mast cells and fibroblasts were not observed previously in vivo or in vitro, although in vitro studies have shown that a number of functionally critical interactions may occur between these cells. Our morphological findings suggest that, in vivo, fibroblasts interact with mast cells and may influence their maturation.

Distribution of exoantigens and a 43-kDa glycoprotein (gp43) in the yeast and mycelial forms of Paracoccidioides brasiliensis

Objective. Paracoccidioides brasiliensis antigens (strain 113) were located at ultrastructural level in both yeast and mycelial forms of the fungus. The reactivity of the sera employed was analysed. Materials and methods. Immunofluorescence and ultrastructural protein A-gold immunolabelling techniques were performed using two polyclonal antisera: one against P. brasiliensis exoantigens and the other against a 43-kDa glycoprotein (gp43). Immunoblotting assays were employed to define reactivity of these antisera with somatic and metabolic antigens of both forms of the fungus. Results. The techniques employed revealed in both yeast and mycelial forms of P. brasiliensis a similar antigenic distribution. The antigens deposits were seen within the cytoplasm, and over the cell wall of the fungus. The anti-exoantigen serum recognized several bands in both forms of the fungus. The anti-gp43 serum reacted strongly with the 43-kDa fraction and weakly with few other fractions. Conclusions. Immunocytochemical techniques suggest a protein synthesis within the cytoplasm followed by excretion through the cell wall. Similar results employing both polyclonal antisera were obtained.

Ultrastructural study of the coagulating gland of Wistar rats submitted to experimental chronic alcohol ingestion

Morphological changes of coagulating gland of Wistar rats submitted to the experimental chronic alcoholism were noted. Ultrastructurally, it was observed reduction of the granular endoplasmic reticulum cisternae and nuclei with basal position and irregular shape. The epithelial cells presented pycnotic nuclei and the mitochondrial cristae disappeared, characteristic of cellular degeneration.

Features of myoneural junctions in the extraocular muscles of the opossum (Didelphis albiventris)

The myoneural junctions present in the opossum (Didelphis albiventris) extraocular muscles were studied through histochemical and ultrastructural techniques. Three different types of junction were shown: two single types, 'en grappe' and 'en plaque', present in the middle third of the muscle fibers; and one multiple type, more rare and observed in the distal third of the muscle.

Structural characteristics of the superior venae cavae wall at the intrapericardium segment in adults and aging individuals

The authors admit that the conjunctive-muscular constitution of the walls of the superior venae cavae throughout the length of the intrapericardium segment and the debouchement in the right atrium, associated with the presence of a myocardium sheath can be made up of a functional device of sphincter form able to act on the control of the blood flow to the interior of the arterial chamber as well as stopping blood flow during the arterial systole. The fixation of the venous wall to the deep chamber of the serous pericardium, contributes to growth in resistance during the elevation of venous pressure, making possible the preservation of integrity of the superior venae cavae. The expansion of fasciculi of nodal fibers in the right wall of the superior venae cavae permits that the unlocked impulse in the S-A node also reaches the vascular wall contributing to the shortening and diminution in caliber of the vein.

Peripheral ameloblastoma.

A case of peripheral ameloblastoma in a 57-years-old woman is presented, along with a discussion of the clinical and histological characteristics of the lesion. After clinical and radiographic examinations, and with a differential diagnosis of pyogenic granuloma, an excisional biopsy was performed and the material collected was sent for histological examination. On the basis of the histopathological diagnosis, a second operation was performed with a wide safety margin, including bone tissue, which did not show any involvement with the odontogenic neoplasm.

Secretion of salivary glands of the Brazilian termite Serritermes serrifer Hagen & Bates (Isoptera : Serritermitidae)

The salivary glands of termites are composed of several secretory acini connected by ducts. These glands, in the Brazilian termite Serritermes serrifer, were examined through the electron microscope. The ultrastructure of worker salivary acinus revealed central ductule cells and four different types of cells. Cells of type I contain an abundance of electron-lucid vacuoles of various sizes which fuse to form enormous vacuolar structures that fill up most of the cell. Cells of type II are narrow cells in which the secretion is contained in small clear vacuoles of approximately equal diameter. Both of these cellular types have numerous Golgi bodies and rough endoplasmic reticulum. Type III or parietal cells have an apical plasma membrane deeply infolded and lined by microvilli. This type of cell is located in the acinar periphery and occurs in pairs. Cells of type IV are completely filled with electrondense secretion. The secretory granules can be small in some cells or large and similar to fingerprints in others. This is the first report of the occurrence of these spiral or concentric rings of dense material in the salivary gland of Isoptera.

Ultrastructural and morphometric aspects of ageing in the retinal capillaries of rats

Age-related morphological, ultrastructural and morphometric changes in the capillaries of the superficial and deep plexuses of the rat retina were studied in animals aged from 3 to 15 months. Our results suggest that age-related morphological alterations start occurring in the retina of rats at about 12 months of age. Increased glycogen deposits, pinocytotic vesicles, residual bodies and cell debris were observed in both the endothelial and pericytic cells of 12- and 15-month-old animals. In addition, heterogeneous osmiophilic accumulations, electron-transparent spaces were observed in the basement membrane as well as projections of the basement membrane towards the neighboring cells. Morphometric examination of the two vascular plexuses studied did not show differences in the area of the endothelial or pericytic cells, basement membrane or vascular lumen between rats of different ages.

Cryopreservation of equine embryos with glycerol plus sucrose and glycerol plus 1,2-propanediol.

Six or 7-day-old equine embryos were divided into 4 groups; Group 1, n = 15, Day 7 embryos destined for immediate transfer; Group 2, n = 15, Day 6 embryos destined for deep-freezing with glycerol plus sucrose as cryoprotectant; Group 3, n = 10, Day 6 embryos destined for deep-freezing with glycerol plus 1,2-propanediol as cryoprotectant and Group 4, n = 3, fresh embryos destined for ultrastructural analysis. All the frozen/thawed embryos were transferred to recipient mares, except 3 embryos in Group 3 that were subjected to ultrastructural analysis. After thawing the cryoprotectants were removed by successive dilutions in PBS + 15% v:v fetal calf serum (FCS) containing decreasing concentrations of the cryoprotectants. Pregnancy was diagnosed ultrasonographically in 53.3%, 13.3% and 0% of the mares in Groups 1, 2 and 3 respectively. Ultrastructural analysis showed differences between frozen/thawed and fresh embryos. In the former, embryonic cells were deformed and showed dilation of the intercellular and perivitelline spaces, a decrease of desmosome number in the junctional complexes, few microvilli on the apical surface of the trophectoderm and an almost total absence of pinocytotic vesicles. Most of the mitochondria showed regions containing dilation and irregularities on the cristae, which appeared electron-dense. The results obtained with Groups 2 and 3 embryos showed that the cryoprotectants employed were not effective in protecting the embryos against damage during freezing and thawing. Indeed, the ultrastructural changes observed in the Group 3 embryos explained the absence of any established pregnancies in this group of mares.

The structure of the human temporomandibular joint disc: A scanning electron microscopy study

The articular disc of the temporomandibular joint was studied in fetuses (16 to 39 weeks of intrauterine life), infants (up to 4 months of age), dentulous adults (aged 30 to 39 years), and completely edentulous adults (aged 60 to 69 years) by scanning electron microscopy. The constituent bundles of collagen fibers were stratified and were oriented anteroposteriorly, laterolaterally, and obliquely in the middle portion of the disc. A ring of laterolateral bundles constituted the main feature of the thick posterior portion. In the anterior portion of the disc, the fibers were anteroposteriorly and obliquely oriented. On the superior and inferior surfaces of the disc, a thin layer of perpendicularly arranged collagen fibers covered the underlying, thick, laterolateral oriented collagen fibers.

Ultrastructural study of the lateral lobe of the prostate of Wistar rats submitted to experimental chronic alcohol ingestion

Alcoholism is considered today one of the most serious social and medical problems. Different investigators have demonstrated that chronic exposure to alcohol causes morphological and physiological changes in the testes and in the accessory sex glands, in the prostate in particular. In the present study, experimental rats were divided into groups receiving sugar cane brandy diluted to 30° G.L. (30%, v/v) and Purina ration ad libitum for 60, 120, 180, 240 and 300 days, respectively. At the end of each period the animals were sacrificed and the lateral lobe of the prostate was collected for histological examination. The results showed atrophied epithelium, accumulation of lipidic droplets and rupture of the microvilli that line the cell surface facing the lumen of cells of the secretory epithelium of the lateral lobe of the prostate.

Comparative structural analysis of neuromuscular junctions in mice at different ages

The authors studied the histochemical and ultrastructural modifications that occur in the neuromuscular junctions (NMJ) of fibularis longus muscles of mice with an age range of 3 to 21 months. Twenty-four male and female animals were killed at 3, 5, 14 and 21 months of age: 7 of them at 3 months, 4 of them at 5 month, 9 at 14 months and 4 at 21 months. The fibularis longus muscles were processed and their NMJ examined with the transmission electron microscope. The most relevant changes were associated with the degeneration and retraction of terminal axons, i.e., axons poor in synaptic vesicles with degenerated mitochondria, and exhibiting multivesicular bodies and vacuoles; exposed and widened junctional folds and cytoplasmic processes of Schwann cells located in the synaptic gutter. The presence of lysosomes or lipofuchsin in the juxtajunctional sarcoplasm was also noted. These observations suggest that the phenomena of retraction and budding occur in the NMJ with advancing age, with a predominance of events associated with degeneration, leading to profound changes in NMJ shape.

Morphological aspects of the mid-palatal suture in the human foetus: A light and scanning electron microscopy study

Morphological features of the mid-palatal suture were studied in human foetuses from 4 to 9 months of intra-uterine life. The foetuses were divided into three age groups, GI (16-23 weeks), GII (24-31 weeks) and GIII (32-39 weeks). The mid-palatal suture in GI foetuses is rectilineal in form with a wide space between the palatal processes of the maxilla. The suture has a sinuous nature in GII and GIII foetuses due to growth of the bone processes crossing the mid-line. A wide zone of cellular proliferation observed in GI narrows in GII and GIII foetuses. The imbricating nature of the suture in GII and GIII is caused by bone growth adjacent to the mid-palatal suture. Sharpey's fibres, emerging from the bone processes, run to the median region of the mid-palatal suture and are observed from GI foetuses onwards. The collagen fibres of the mid-palatal suture are orientated transversely under the oral epithelium and exhibit a regular meshwork with a predominance of sagittal fibres in the median region of the suture. These fibres are orientated transversely and obliquely at the junction with the nasal septum.