Microscopic and ultrastructural lesions of the ureter and renal pelvis in sows with regard to Actinobaculum suis infection

Tissues from ureter and renal pelvis of 18 sows naturally (n = 15) and experimentally (n = 3) infected with Actinobaculum suis (former Actinomyces, Eubacterium suis) were studied using light and scanning as well as transmission electron microscopy. The results were compared with the findings from 11 clinically healthy sows as controls. The lesions in both the ureter and renal pelvis of naturally and experimentally infected animals were similar. In severe cases there were necrotizing ureteritis and pyelitis with accumulation of bacterial colonies in some cases. Several superficial epithelial cells were found phagocytosing necrotic debris. In mild cases the main lesions included epithelial cell hyperplasia, desquamation of the superficial epithelial cells and goblet cell metaplasia with intraepithelial cyst formation. The goblet cells were found in the superficial as well as in the intermediate cell layers. Generally, it was observed that severe purulent ureteritis and pyelitis/ pyelonephritis in sows were to be expected only in mixed infection of A. suis with other bacteria. The findings were compared and discussed with the changes in the infected urinary bladder of sows and the alterations induced by urinary tract infection in man.     

Uroplakin expression in the urothelial tumors of cows.

Expression of uroplakins (UPs) was investigated in 20 bladder tumors from cows that had been suffering from chronic enzootic hematuria for several years. In dysplastic urothelium and papillomatous proliferations, UP expression was evident both as luminal and intercellular staining. UPs appeared to clearly define the plasma membrane of luminal cells and the borders of cells placed in deeper layers, whether or not these intermediate cells were adjacent to superficial ones. Occasionally, some intermediate cells showed a remarkable cytoplasmic immunoreactivity. The pattern of UPs in grade I tumors was characterized by an evident discontinuity of luminal staining and by the presence of numerous intermediate cells showing a diffuse intracytoplasmic positivity for UPs. In grade II tumors, there was a decrease of luminal and intermediate cells showing UP expression and an apparent increase of clusters of intermediate cells with intracytoplasmic reactivity for UPs. In grade III tumors, immunoreactivity was heterogeneously distributed and a severe loss of UP-positive luminal and intermediate cells could be seen. Focally, superficial and deeper cells showed strong membraneous immunoreactivity that marked and delimited single cells, with complete circumferential peripheral staining clearly evident. UP expression in bladder tumors of cows reported in this study is similar to the UP pattern of some urothelial tumors in humans. Although UP expression is remarkably changed in bladder carcinogenesis of cattle, the UP gene(s) remains expressed during cell transformation and tumor progression.     

Epithelium lining the rostral portion of the porcine nasal mucosa

Epithelial tissues from the rostral half of the pig nasal cavity were prepared for light and electron microscopy. The predominant epithelial cell type at the luminal surface was cuboidal with surface microplicae or microvilli and a multilobate nucleus. Pinocytotic vesicles were a common feature of the adluminal cytoplasmic zone of these superficial cuboidal cells. Other cell types included basal cells, intermediate cells and, occasionally, goblet and ciliated cells. Basal cells contained vesicles located adjacent to the basal lamina. This transitional mucosa may be specialised for sampling substances from the luminal surface preliminary to releasing cytokines and, or, presenting immunogens to intraepithelial lymphocytes.     

Licht- und elektronenmikroskopische Studien zur Struktur des normalen Blasenepithels beim weiblichen Schwein

A light- and electron-microscope investigation was performed to examine the normal structure of the porcine urinary bladder. Tissue biopsies were studied obtained from 10 healthy female pigs (four weanling pigs, six sows). The bladder wall showed a typical stratification consisting of a tunica (t.) mucosae, t. submucosae, t. muscularis and t. serosa. The mucosa consisted of an epithelium transitionale, a lamina propria, and a lamina muscularis mucosae. The urothelium was composed of a basal layer, one or more intermediate layer(s), and a superficial layer. The urothelial cells of all layers were connected by desmosomes, while tight junctions linked adjacent superficial cells. Surface cells were lined by a layer of mucus, which is believed to provide an important barrier against bacterial infection. The surface of the superficial cells was also characterized by numerous irregularly arranged microplicae. By contrast, intermediate cells, which are assumed to be immature cell forms, showed microvilli-like structures. When desquamation of superficial cells takes place, differentiation of underlying intermediate cells is accompanied by merging of microvilli to form microplicae. The morphology of the bladder surface structures may play an important role in the ability of bacteria to adhere to the urothelium.     

Diagnostic importance of urothelial cells of the dog and cat

The cells lining the canine and feline urinary tract and their role in the diagnosis of urological diseases in small animals is assessed. The urothelium was found to consist of transitional epithelial cells ranging from the calyces to the urethra. Caudate cells were found lining the ureter, renal pelvis and the calyces. There was no feature that could be used to distinguish the transitional cells from different parts of the urothelium. Squamous cells were found lining the urinary tract from the trigone to the vagina in females and to the urethra in male animals. Hydropic degeneration in the form of vacuolation of the cytoplasm, granulation and total loss of cytoplasm was one of the urine-induced degenerative changes recorded in the transitional cells. The significance of the degenerative changes in the management of urological problems is discussed.     

Ultrastructural mucosal injury after experimental ischemia of the ascending colon in horses.

The ultrastructural injury that develops sequentially in the ascending colon during experimentally induced ischemia was examined in 6 halothane-anesthetized horses. Colonic ischemia was created by 2 types of vascular occlusion 24 cm proximal and distal to the pelvic flexure. In all horses, transmural vascular compression was created. The colonic venous circulation was obstructed in 3 horses, whereas in the other 3 horses, arterial and venous circulation was obstructed. Two additional horses were anesthetized as controls for determination of any morphologic alterations associated with the experimental protocol. Full-thickness colonic biopsy specimens were obtained from the antimesenteric border of the pelvic flexure at 0, 0.25, 0.5, 1, 1.5, 1.75, 2, 2.25, 2.5, 3, 3.5, 4, 4.5, and 5 hours during occlusion, and were studied by light and transmission electron microscopy. Morphologic alterations did not develop in the colon of control horses. Mucosal congestion was observed by light microscopy in the colon of horses with experimentally induced ischemia, but congestion developed early in those with obstructed colonic venous circulation, compared with those having arterial and venous obstruction. Inter- and intracellular vacuolation and loss of staining initially resulted in groups of 3 to 5 superficial luminal epithelial cells. Alterations in the glandular epithelium lagged behind those in the superficial epithelium, but were observed in both groups by 2 hours of obstruction. These changes progressed to 100% sloughing of all epithelium by 4.5 to 5 hours. The initial cellular alterations, which were observed by transmission electron microscopy, developed at 0.25 hour in horses with colonic venous obstruction and was characterized by inter- and intracellular edema.(ABSTRACT TRUNCATED AT 250 WORDS)     

Fine structure of the retinal pigment epithelium, Bruch's membrane and choriocapillaris in the ostrich (Struthio camelus)

The fine structure of the retinal pigment epithelium (RPE), Bruch's membrane and choriocapillaris in the ostrich (Struthio camelus) was investigated by using light microscopy and transmission electron microscopy. In this species, the RPE consisted of a single layer of low columnar cells. The epithelial cells were joined laterally by two type junctions, zonulae occludentes and zonulae adherentes located in the midregion of the cells. These cells displayed numerous deep basal infoldings and thick extensive apical processes, which enclosed the outer segments of the rods. The epithelial cell nuclei were large, vesicular and located basally within the epithelial cells. Smooth endoplasmic reticulum was very abundant, while rough endoplasmic reticulum was scarce. Mitochondria of various shapes were abundant basally while polysomes were plentiful and widespread. In the light-adapted state melanosomes were located in the apical region and in apical processes of the epithelial cells. Myeloid bodies were large, numerous and often showed ribosomes on their outer surface. Bruch's membrane (complexus basalis) was typical pentalaminate throughout the retina, as noted in the majority of other vertebrates. The endothelium of the choriocapillaris facing Bruch's membrane was extremely thin but only moderately fenestrated. Some of the fenestrations displayed a double-layered diaphragm while the majority showed the more typical single-layered diaphragm noted in most species.     

Morphological study of the Forestomach of the Japanese Serow (Capricomis crispus)

Details of the morphology of the forestomach of the Japanese serow (Capricornis crispus) were examined macroscopically, and by light and scanning electron microscopy. The rumen was sac-like in shape, and the right accessory longitudinal groove was not visible externally. The reticulum was relatively small, while the omasum was oval and large. Inside the rumen, even in the dorsal sac, the ruminal papillae were densely distributed, although absent on the pillars. The caudodorsal coronary pillar was indistinct. In the ruminoreticular fold, ruminal papillae were observed even on the reticulum side. In the reticulum, the primary reticular fold was apparent and the ill-defined secondary folds were also detected in some reticular cells. In the omasum, the omasal laminae of four sizes were recognized. The fourth order of laminae was occasionally absent. Histological sections of ruminal papillae revealed that softly keratinized epithelium covered the entire ruminal mucosa. In the reticulum, soft keratinized epithelium was observed throughout, with the exception of the tips of reticular papillae on which the epithelium showed evidence of hard keratinization. The epithelium of the omasal laminae was moderately keratinized. On the floor of the reticular groove, interlaminar area and in the omasal groove, the accumulations of numerous eosinophilic cells were observed in the superficial region. Under the scanning electron microscope, shallow transverse grooves were seen on the surface of the ruminal papillae. In general, the surface structure seemed to be similar to that of sheep rather than cattle. Cellular formations of the collagen fibrils were observed at the subepithelial region. In conclusion, examination of the forestomach allows classification of the Japanese serows as requiring an intermediate type of feeding habit and being between concentrate selectors and grass-roughage eaters from a morphological view.     

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

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.     

Continual maintenance of the blood-testis barrier during spermatogenesis: the intermediate compartment theory revisited

Tight junctions occur between the lateral processes of neighboring Sertoli cells that divide the seminiferous epithelium into two compartments: basal and adluminal compartments. These tight junctions constitute the blood-testis barrier (BTB). The established theory that the BTB must open when spermatocytes translocate from the basal compartment to the adluminal compartment is marked by one contradiction, that is, normal spermatogenesis occurs in the testis because the BTB is expected to constantly seclude the adluminal compartment from the basal compartment in order to protect haploid germ cells from the autoimmune system. Subsequently, another concept was proposed in which two BTBs divide the seminiferous epithelium into three compartments: basal, intermediate and adluminal compartments. It has been suggested that the transition from the basal region to the adluminal region without the BTB open occurs through the agency of a short-lived intermediate compartment embodying some primary spermatocytes. In contrast, the results of recent findings in the molecular architecture of the BTB suggest that the BTB in the seminiferous epithelium must "open". In this paper, I re-examine the BTBs of boar and experimental cryptorchid mouse testes by transmission electron microscope (TEM). TEM analysis showed that an atypical basal compartment existed in the thin seminiferous epithelium of 14-day post-cryptorchid mice testes. In developmental boar testes, ectoplasmic specialization (ES) of the seminiferous epithelium showed dynamic behavior. The intermediate compartment was clearly observed between the basal and adluminal compartments of the mature boar seminiferous epithelium. ESs were observed between Sertoli cells and spermatids at all developmental stages, including early, late and mature. Furthermore, ESs were situated on the apical surface of the seminiferous epithelium. From these results, I propose that the BTB is continually maintained during spermatogenesis and suggest a model of ES circulation in the seminiferous epithelium.     

Fine structure of the retinal pigment epithelium, Bruch's membrane and choriocapillaris in the horse

The fine structure of the retinal pigment epithelium (RPE), Bruch's membrane and choriocapillaris was investigated by light and transmission electron microscopy in both the tapetal and non-tapetal fundus of the horse eye. In all locations, the RPE consisted of a single layer of low cuboidal cells. The epithelial cells were joined laterally by apically located tight junctions. These cells displayed numerous basal infoldings and abundant thin apical processes which enclosed the rod outer segments. The epithelial cell nuclei were large and located basally. Within the epithelial cells, smooth endoplasmic reticulum was very abundant, while rough endoplasmic reticulum was scarce, polysomes and mitochondria, which often display a ring-shaped structure, were abundant. Melanosomes were abundant in the non-tapetal area but absent in the tapetal area. Bruch's membrane was pentalaminate throughout the retina. The endothelium of the choriocapillaris was heavily fenestrated.     

Fine structure of the retinal pigment epithelium, Bruch's membrane and choriocapillaris in the camel

The morphology of the retinal pigment epithelium (RPE) and closely associated Bruch's membrane and choriocapillaris was investigated by light and transmission electron microscopy in the camel (Camelus dromedarius). The study showed that RPE is composed of a single layer of hexanocuboidal cells that were joined laterally by a series of apically located tight junctions. In addition, adjacent from internal side of cell membrane at the level of tight junctions, an undefined structure which resembled the myofibrillar organization of skeletal muscles in appearance was located. These cells displayed numerous short basal infoldings and abundant thin apical processes which enclosed the rod outer segments. The epithelial cell nuclei were large, vesicular and eccentrically located. Within the epithelial cells, smooth endoplasmic reticulum was very abundant, while rough endoplasmic reticulum was present only in small amounts. Polysomes were also numerous and the mitochondria often displayed a ring-shaped structure. Lipofuscin granules were plentiful in all locations. Bruch's membrane (complexus basalis) was typically pentalaminate throughout the retina. The endothelium of the choriocapillaris facing Bruch's membrane was extremely thin and heavily fenestrated. These fenestrations displayed typical single-layered diaphragm as noted in most species.     

Immunohistochemical detection of Ym1/Ym2 chitinase-like lectins associated with hyalinosis and polypoid adenomas of the transitional epithelium in a mouse with acute myeloid leukemia

An 8-month-old PML/RARalpha knock-in female mouse developed a promyelocytic-like myeloid leukemia with an expected latency. At necropsy, besides the typical findings associated with myeloid leukemia, a severe unilateral hydronephrosis was observed. By histopathologic examination, 2 polypoid adenomas arising from the transitional epithelium of the renal pelvis and ureter were detected. The epithelial cells of the polypoid adenomas showed accumulation of hyaline eosinophilic material within the cytoplasm. Large amounts of extracellular eosinophilic crystals were also associated with the transitional cell adenomas. Immunohistochemical analysis revealed that the eosinophilic intracytoplasmic material and the extracellular eosinophilic crystals were composed of Ym proteins. A unilateral hyaline droplet tubular nephropathy was associated with the myeloid leukemia. Expression of Ym proteins characterized both the neoplastic myeloid infiltrates and the tubular hyaline droplets. In the present PML/RARalpha knock-in female mouse, the accumulation of Ym proteins associated with the myeloid leukemia and with the polypoid adenomas of the transitional epithelium underlies 2 distinct pathogenetic mechanisms.     

Ultrastructure of canine urinary bladder carcinoma

Luminal and intraepithelial asymmetric unit membrane plaques were found in the urinary bladder urothelium of normal dogs. Tight junctions were found only at the apical poles of the luminal cells. In four dogs with spontaneous urinary bladder carcinomas the asymmetric unit membrane plaques were replaced by symmetric unit membrane. In the neoplastic luminal cells the tight junctions were partially attenuated. Invasive and metastatic neoplastic cells had some tight junction at the stromal interface. Some gap junctions were seen in the normal urothelium but not in the neoplastic cells. The amount of desmosomes in the neoplastic cells varied according to their direction of differentiation (transitional, squamous or glandular).     

Comparative histomorphological and ultrastructural study of the luminal epithelium of the isthmus in laying and moulting domestic fowls (Gallus domesticus)

This study describes ciliated, nonciliated and mitochondrial luminal epithelial cells of the isthmus in laying and moulting domestic fowls using histological and ultrastructural techniques. The ciliated cells were nonsecretory, while numerous electron‐dense secretory granules were present in the nonciliated cells of laying birds. Mitochondrial cells, occurring in two morphologically distinct forms, constituted the third type of epithelial cell present in the isthmus. The SEM study showed that the luminal epithelium was dominated by ciliated cells, the cilia of which partially obscured adjacent nonciliated cells. The involution of the luminal epithelium in moulting birds occurred via autophagy, apoptosis and necrosis. Autophagic inclusions, which included autophagosomes and autolysosomes, were present in the early degenerative phases of ciliated, nonciliated and mitochondrial cells. Nonciliated cells underwent degeneration via apoptosis, which was characterized by nuclear and cytoplasmic condensation. Apoptotic and necrotic ciliated cells were evident during the intermediate and advanced stages of regression. The presence of apoptotic cell death was confirmed using the TUNEL assay. Loss of cilia via the formation of cilia packets was observed using TEM and SEM. Necrotic cell death occurred in mitochondrial cells during the intermediate and late stages of degeneration. In conclusion, the findings of the study on isthmus involution in moulting birds suggest that autophagy is a process confined to the early stages of degeneration, while apoptosis and/or necrosis occur in the terminal stages of regression.     

Intestinal trichomonads (Tritrichomonas mobilensis) in the natural host Saimiri sciureus and Saimiri boliviensis

A retrospective study of cecal and colonic tissues from 28 squirrel monkeys (Saimiri sciureus and Saimiri boliviensis) demonstrated enteric trichomonads within luminal crypts. Twenty-one of 28 (75%) had trichomonads in the mucosal epithelium either in cup-like depressions or intraepithelial vacuoles. Organisms were also beneath the superficial luminal mucosal epithelium and between the basement membrane and crypt epithelial cells. Immunoperoxidase staining also identified organisms within the lamina propria and submucosa. Additional histologic changes included mucosal ulceration, multifocal cryptitis, and focal epithelial necrosis. Most areas containing trichomonads did not have an associated inflammatory response.     

Morphological Characteristics of the Heal Peyer's Patches in the Rhesus Macaque: a Histological and Ultrastructural Study

Ileal Peyer's patches of rhesus macaques were investigated by light and electron microscopy (scanning-electron microscopy, transmission-electron microscopy). The results were compared with findings in other species. Differences were found concerning the shape of the dome area, the composition of the dome epithelium and the apical membrane of M cells: in the rhesus monkey, hemispherical domes bulge into the intestinal lumen. The dome epithelium is composed of three populations of gut epithelial cells: absorptive enterocytes as the predominant cell type; goblet cells; and M cells (‘microfold bearing’ or ‘membraneous’ gut epithelial cells). The apical membrane of M cells forms irregular protrusions.     

Light and electron microscopic studies of the trachea in the one-humped camel (Camelus dromedarius)

Histology of trachea of camel (Camelus dromedarius) was studied using light, scanning (SEM) and transmission electron microscopy (TEM). Tissue samples taken from the trachea (proximal, middle and distal part) were routinely prepared for histology (LM, EM) and stained with haematoxylin and eosin, Van Giesson (VG), Alcian blue, Periodic acid schiff (PAS), Masson's trichrome (MT), Verhof, PAS-VG and PAS-MT. The trachea of camel consists of 66-75 incomplete cartilaginous rings of hyaline. The lamina epithelium is composed of pseudostratified-ciliated columnar epithelium with many goblet cells. Submucosal layers were loose connective tissue with many elastic fibres. The mucosal and submucosal layers were 517.2 +/- 61.6 microm (n = 20) thick. Submucosal glands were tubuloalveolar with mucous (acidic and neutral) secretions. Trachealis muscle was attached to the inside sheet of tracheal cartilage. Ultrastructural studies showed that surface epithelium is pseudostratified with mucus-producing goblet cells, ciliated and basal cells, similar to other mammals. The ciliated cells contained many mitochondria, oval nucleus and many big granules. In scanning electron microscopy (SEM) studies, viscoelastic layers were observed on the epithelial surface of trachea, and there were highly condensed cilia under this layer.     

Electron microscopic study of leucocytic infiltration of the mammary teat duct during infection with Staphylococcus aureus

Leucocytic response to Staphylococcus aureus infection was observed in the bovine mammary teat duct using transmission electron microscopy. Leucocytes migrating across the stratified squamous epithelium were observed in close association with areas colonised by cocci. Leucocytes gained access across the epithelium to the teat duct lumen by: passage as luminal cells desquamated; migration through degenerate cell cytoplasm; and penetration of cell junctions. The results provide evidence of marked leucocytic infiltration into ductal tissue which may participate in the cellular response to mastitis.     

Embryonic and postnatal differentiation of olfactory epithelium and vomeronasal organ in the Syrian hamster

The details of the embryonic and postnatal differentiation of the olfactory epithelium (OE) and vomeronasal organ (VNO) were examined by light and electron microscopy in the Syrian hamster. At 10 days of gestation, the nasal placode is invaginated to form the olfactory pit on either side at the rostral end of the embryo. Abundant mitotic figures are observed near the free surface of the epithelium lining the olfactory pit. At 11 days of gestation, the mass of the epithelium lining a recess is separated from the medial wall of the olfactory pit to form the VNO. At 13 days of gestation, mitotic figures become observable in the basal layer of the vomeronasal sensory epithelium (VSE) in addition to the superficial to middle layers, while in the OE mitotic figures are observed mainly in the middle to basal layer. At 1 day after birth, the OE is almost complete in differentiation. On the other hand, the VSE differentiate slowly to retain some immature properties even at 10 days after birth. These findings suggest that the olfactory function seems to be solely ascribed to the OE for a while after birth. The significance of mitotic figures are discussed in the course of development with special reference to the origin of the nasal placode from the central nervous system.