Showing papers on "Apical cytoplasm published in 2006"

Brush border spectrin is required for early endosome recycling in Drosophila.

Abstract: An apical brush border is a characteristic of many mature epithelia. This dynamic structure consists of dense microvilli supported by F-actin bundles that protrude into the apical cytoplasm, where they are crosslinked by spectrin and myosin II to form the terminal web. Little is known about the terminal web, through which vesicles transit to and from the apical membrane. Analysis of mutations in beta(Heavy)-spectrin, the Drosophila brush border spectrin, reveals that this protein is necessary for the maintenance of Rab5 endosomes in the midgut. As a consequence, an apical H+ V-ATPase that is probably responsible for lumenal acidification is lost both from the brush border and Rab5 endosomes. Epistasis tests indicate that beta(Heavy)-spectrin is required during endocytosis after Dynamin and before Rab5-mediated endosome activities. These data are consistent with the location of spectrin in the terminal web, and suggest that this molecule is required for correct sorting decisions at the early endosome.

Interlobular excretory ducts of mammalian salivary glands: Structural and histochemical review

Abstract: In the major salivary glands of mammals, excretory ducts (EDs) succeed striated ducts. They are for the most part interlobular in position, although their proximal portions sometimes are on the periphery of a lobule, where they occasionally retain some of the structural features of striated ducts. Based on a survey of a broad range of mammalian species and glands, the predominant tissue type that composes EDs is pseudostratified epithelium. In some species, there is a progression of epithelial types: the proximal EDs are composed of simple cuboidal or columnar epithelium that, in the excurrent direction, usually gives way to the pseudostratified variety. Secretory granules are visible in the apical cytoplasm of the principal cells of the EDs of only a few species, but histochemistry has shown the presence of a variety of glycoproteins in these cells in a spectrum of species. Moreover, the latter methodology has revealed the presence of a variety of oxidative, acid hydrolytic, and transport enzymes in the EDs, showing that, rather than simply acting as a conduit for saliva, these ducts play a metabolically active role in gland function. It is difficult to describe a "typical" mammalian ED because it can vary along its length and interspecific variation does not follow a phylogenetic pattern. Moreover, in contrast to intercalated and striated ducts, ED cellular features do not exhibit a relationship to diet.

Lawsonia intracellularis proliferative enteropathy in a filly.

Abstract: Proliferative enteropathy (PE) caused by the obligate intracellular bacterium Lawsonia intracellularis is a disease of high economic impact in swine worldwide. In most other species the disease occurs as a sporadic infection. This paper reports a PE caused by L. intracellularis in a 9-month-old Pura Raza Espanola filly with a history of profuse diarrhoea. Pathological lesions consisted of a severe proliferative enteritis associated with argyrophilic bacteria in the apical cytoplasm of proliferating crypt epithelium. Characteristic PCR products confirmed the presumptive diagnosis of L. intracellularis infection. To our knowledge this is the first report of PE in a horse in Europe caused by L. intracellularis.

Scanning electron microscopic study of the nasolabial cyst: its clinical and embryological implications.

Abstract: Objective: Nasolabial cyst is an uncommon midfacial cyst. It is considered to be a developmental anomaly arising from the rest of nasal respiratory epithelium. Although the cyst is a well-recognized entity, there remains some confusion of its origin, cell types, and ultrastructures. Based on the routine light microscopic study, some authors reported the epithelial cells of the inner lining of the nasolabial cyst were ciliated; some others reported they were nonciliated. To clarify this, a scanning electron microscopic study is needed. Study Design: This was a prospective clinical series. Methods: A transnasal marsupialization method was used to treat 10 patients with nasolabial cyst. With patients under local anesthesia, the roof of the cyst wall and a disk of nearby nasal mucosa were excised together with a sickle knife and scissors. Surgical specimens were dissected and processed for scanning electron microscopy and histochemistry. Patients were followed up for 8 to 65 months. Results: Marsupialization of cysts was successfully performed on all patients. Electron microscopically, the inner surface of the nasolabial cysts in all the cases was lined with nonciliated columnar epithelium consisting chiefly of goblet cells and basal cells. It is suggested that goblet cells contributed to clear, thin, and yellow mucus present in the cyst lumen. Instead of cilia, these epithelial cell surfaces were equipped with numerous short, globular, or irregular microvilli. Apical cytoplasm of adjacent cells did not tightly adhere to each other. Instead, microsulci of 1 to 3 μm in width formed between cells. Cytoplasmic processes from the lateral border spanned the microsulcus and contacted with those from neighboring cells. Conclusion: The novel study has proved that the lining epithelium on the inner surface of the nasolabial cyst is columnar epithelium that chiefly consisted of two types of cells: goblet cells and basal cells. Not present were ciliated cells that were essential in the other portion of the respiratory tract. Numerous microvilli, instead of cilia, covered the inner lining of the nasolabial cyst, probably as a result of lacking the stimulation of air in ventilation as that on the other portion of the respiratory tract. The cilia of the epithelium were ill developed.

Fat absorptive processes in the intestine of the Antarctic fish Notothenia coriiceps (Richardson, 1844)

Abstract: Absorption of lipids by the enterocytes of Notothenia coriiceps, an omnivorous Antarctic and subAntarctic fish, was studied by light and electron microscopy. The lipids are absorbed by the anterior and middle intestine segments. They appear as fat droplets that measure from 0.5 to 7 μm of diameter and which accumulate in the apical cytoplasm within the first 24 h and seem to be the main fat storage form in the enterocytes. Fat is also observed as lipid particles with 60–300 nm inside the rough endoplasmic reticulum and cytoplasmic smooth vesicles. The epithelial intercellular space and the mucosal inner lamina contain lipid particles, which probably are the fat transport form. Our observations show that an intense lipid absorptive process takes place in N. coriiceps digestive system, due to the great extension of the intestine involved and due to the great lipid accumulation found in the epithelial compartment.

Light and electron microscopic observations of fabrication, release, and fate of biphasic secretion granules produced by epididymal epithelial principal cells of the fan-throated lizard Sitana ponticeriana cuvier.

Abstract: The epididymis of the fan-throated lizard Sitana ponticeriana was examined with light and transmission electron microscopy to understand the cellular mechanisms of fabrication of secretion granules in epithelial principal cells, granule release into the lumen, and the fate of the dense structured granules after reaching the lumen. Principal cells of the ductus epididymis, except at the cauda, secrete electron-dense biphasic granules copiously, which decrease in abundance from the initial segment to corpus. The principal cell possesses a prominent Golgi apparatus and all versions of endoplasmic reticulum (ER), rough, smooth, and sparsely granulated. The material of the dense portion of the secretion granules, after processing at the Golgi apparatus, appears to accumulate in large ER cisternae in the supranuclear cytoplasm. It undergoes condensation when the cisternae become condensing vacuoles. Mitochondria appear to play a role in dense granule formation. The condensing vacuoles are displaced toward the apical cytoplasm when the material of the less dense portion is added to the condensing vacuoles at the Golgi area. Thus, the less dense and dense portions of the secretion granules are secreted and added to the condensing vacuoles separately. The composite granules are released into the lumen by exocytosis when the less dense portion merges with the luminal content, whereas the dense portion maintains its structured identity. The latter, initially measuring 1-2 microm in diameter, increases in size several times. It is inferred that these granules release their content gradually, resulting in the appearance of vacuoles, and suggesting that the granules have an insoluble matrix in which there is a sparingly soluble material. The substance leaching out of the granules appears to contribute to keeping the sperm quiescent and alive during storage in the male reproductive tract.

Morphological and functional changes to the uterus of lizards with different placental complexities

Abstract: We compared the uterine component of the placentae of each placental region of two species of lizards, Eulamprus tympanum and Pseudemoia entrecasteauxii, to identify potential routes and mechanisms of nutrient transport. We focused on the uterine epithelium because nutrients must pass though it to reach the embryo. At this point, we have only been able to study two species in detail, but each has a placenta of different complexity and quantitatively different placentotrophy. The uterine epithelium of the chorioallantoic placenta has a different morphology from the omphaloplacenta, and the chorioallantoic placenta of P. entrecasteauxii, the most placentotrophic of the two species, is further differentiated in placentomal and paraplacentomal regions. The chorioallantoic region of E. tympanum, and the paraplacentomal region of P. entrecasteauxii have morphologies indicative of gas exchange epithelia. The blood-uterine lumen distance in P. entrecasteauxii, however, is about one tenth that in E. tympanum, suggesting a greater diffusive capacity for gases in P. entrecasteauxii. The omphaloplacenta of both species has a similar structure, with hypertrophied cells, electron-dense granules in the apical cytoplasm and vesicles budding off into the uterine lumen. This result is particularly interesting because E. tympanum exhibits little net nutrient transfer to the embryo during pregnancy. Nutrient provision across the omphaloplacenta in both species occurs by histotrophy. The placentome of P. entrecasteauxii also has a morphology suggestive of nutrient provision, but by some non-histotrophic mechanism and may be very important in the evolution of substantial placentotrophy.

Pathophysiology in Microvillus inclusion disease.

Abstract: Microvillus inclusion disease (MID) is a congenital disorder with the clinical signs of watery diarrhea often beginning in the first days of life. The main pathological features of the disease include a villus atrophy and an accumulation of periodic acid-Schiff (PAS)-positive material within the apical cytoplasm of enterocytes on the light microscopy level. Electron microscopic criteria are pathognomonic consisting of an increased amount of secretory granules preferentially in crypt epithelial cells and of the presence of microvillus inclusion bodies (MIBs) which are most frequently found in villus enterocytes. Until now the basic molecular defects have not been disclosed completely. In this review we discuss the actual pathogenetic hypothesis and the therapeutic options besides small bowel transplantation.

Bioaccumulation of Heavy Metals in Intestine of Nacella concinna

Abstract: Immunohistochemical and ultrastuructural experiments were conducted to find out heavy metal accumulation in the intestine of an Antarctic gastropod Nacella concinna. According to the immune-histochemical experiment the apical cytoplasm of the intestinal epithelium showed positive reactions to anti-MT (rnotallothionein), indicating the presence of MT, a metal-binding protein involved in metal detoxifying process. In the transmission electron microscopic observations, the epithelial cells of the intestine exposed to Cd for over three hours showed irregular nuclear membranes, secretory granules, and probable metal granules. According to the SEM-EDS experiments on the intestine, concentration of Pb in the apical epithelium was in inverse proportion to that in the intestinal lumen. After exposing to Cd for over three days, S was rapidly reduced. Ca and Zn were rapidly increased after exposure to Cd. These elements are supposed to be concerned with the MT-reaction in the intestine. laken together, these data suggest that N. concinna could be used as a potential biomarker species.

Localização histoquímica de algumas hidrolases no epidídimo do gerbilo

Abstract: This study mainly showed that alkaline phosphatase expression had been present in the proximal regions of the epididymidis ductus of the gerbil which comprised the initial segment and proximal caput. The reactivities of acid phosphatase and ATPase were strong in the proximal and distal regions of the epididymidis ductus at the level of the apical cytoplasm and epithelium, except at the corpus level, a very thin isthmus located between the caput and cauda epididymidis, and as a general rule a low enzymatic reactive region of the epididymis of gerbil. SDH revealed also low activities in all the regions and regional structures of the duct, except into the luminal content formed by storaged spermatozoa, prior on the cauda level. The enzymes presented in the epididymis were correlated to some histophysiological roles such as the enzymatic mediation of endocytosis, secretion, absorption and active transport concerning to phosphatases and ATPase and a possible mitochondrial role of SDH could occur at the spermatozoa level in which the middle pieces were formed by a great amount of mitochondria.

A comparative ontogenic study of urinary bladder: impact of the epithelial differentiation in embryonic and newborn rats.

Abstract: The present study aimed to show the cellular and subcellular distribution of glycogen content during the differentiation of urothelial cells from simple cuboidal to stratified transitional epithelium. Bladder samples were taken from rat embryos on the 15th to 19th days and newborn at 21st day. During the development of the bladder, the formation of fusiform vesicles, asymmetric unit membrane (AUM) and microridges were examined with staining with haematoxylin-eosin and periodic acid Schiff for light microscope and periodic acid-thiocharbohydrazide-silver proteinate for transmission electron microscope. The topographical changes of luminal differentiation were examined with the scanning electron microscope. The urothelium was simple cuboidal from 15th till the 17th days of gestation. Glycogen content was present in the cytoplasm till the 18th day of gestation. At the early stage (16th day) of gestation, the apical surface contains microvilli that points the undifferentiated cells. The density of microvilli decreased and ropy microridges appeared at the 17th day of gestation. The small discoid vesicles lined with AUM developed at the apical cytoplasm of the surface cells at the 17th day of gestation. After this stage, both the density of microridges and large and elongated fusiform vesicles increased. The differentiation of the urothelium begins with the formation of the round and small vesicles, continues with the formation of the AUM and at the final stage there is a decrease in both glycogen content and the appearance of the microridges at the luminal surface of the urothelial cells.

Morphologic, Histochemical, and Immunohistochemical Characterization of Tracheobronchial Respiratory Glands in South American Sea Lion Otaria flavescens (Pinnipedia, Mammalia)

Abstract: Tracheobronchial airways from Otaria flavescens routinely were processed for histological, histochemical, and immunohistochemical methods to study individual mucusproducing cells (IMPC and submucosaI glands. The IMPCs were interspersed in the epithelium of the trachea. They showed neutral and weakly acidic and carboxylated glycoconjugates. Only IMPCs in the trachea secrete sialylated glycoconjugates. Submucosal glands were formed by 1) collecting duct lined by a ciliated pseudostratified to simple columnar epithelium without cilias. They showed neutral and carboxylic glycoconjugates. 2) Glandular sinus, a branched secretory unit in which the lining epithelium showed two possible secretory mechanisms: merocrine type of neutral glycoconjugates and apocrine type of sialylated and sulphated or carboxylated glycoconjugates, with positive reaction for proteins. 3) Glandular branched tubules emerging from glandular sinuses were lined by columnar cells with an apical cytoplasm containing neutral and carbo...