Quantification of umu genotoxicity level of urban river water.

In recent years, the request of environmental safety management for carcinogenic substances, mutagenic substances and/or reproductive toxicity substances (CMR) has increased. This study focused on clarifying the genotoxicity level of environmental water and its release source by using the umu test provided in ISO13829. Although a genotoxicity index "induction ratio (IR)" is used in ISO13829, we normalised it to make it possible to compare various environmental water quantitatively to each other as a new index "genotoxic activity (GA=(IR-1)/Dose)". Sample water was collected and concentrated to 100 times or 1,000 times by a solid phase extraction method. As the test results, it was found that GA level in actual river water varied widely from less than the determination limit of 23 [1/L] to 1,100 [1/L] by quantitative comparison, and the value was also equivalent to more than 50 times the level of tap water. The GA level of household wastewater was not so high, but the levels of treated water from wastewater treatment plant (WTP) were from 220 [1/L] to 3,200 [1/L]. Raw sewage of some WTP shows high level genotoxicity. A part of genotoxicity substances, for example 50%, could be removed by conventional wastewater treatment, but it was not enough to reduce the water environmental load of genotoxicity.

Primary small cell carcinoma of lacrimal sac: case report and literature review.

OBJECTIVE: We present the first reported case of primary small cell carcinoma of the lacrimal sac. CASE REPORT: A 67-year-old Japanese woman was referred to our department with a two-month history of left medial canthal swelling, epiphora and occasional nasal bleeding. Nasal endoscopy revealed a readily bleeding tumour in the left inferior meatus. Computed tomography and magnetic resonance imaging scans demonstrated that the tumour was mainly located in the left lacrimal sac. Histopathological studies of a biopsy specimen revealed small cell carcinoma. The patient was treated with four cycles of chemotherapy consisting of cisplatin and etoposide, in combination with radiotherapy. There was no evidence of recurrence or metastasis for five years. CONCLUSION: Small cell carcinoma originating in the head and neck region has been reported to be highly aggressive and to have a poor prognosis. We report a case of primary small cell carcinoma of the lacrimal sac successfully treated with chemo-radiotherapy.

Secretion by striated ducts of mammalian major salivary glands: review from an ultrastructural, functional, and evolutionary perspective.

In addition to their role in electrolyte homeostasis, striated ducts (SDs) in the major salivary glands of many mammalian species engage in secretion of organic products. This phenomenon usually is manifested as the presence of small serous-like secretory granules in the apical cytoplasm of SD cells. The composition of these granules is largely unknown, except in the case of the cat and rat submandibular gland, where the granules have unequivocally been shown to contain kallikrein. In some species, the apical cytoplasm of SD cells contains variable numbers of vesicles, both spherical and elongated, that vary in appearance from 'empty' to moderately dense. In the rat parotid gland, lucent vesicles transport glycoproteins to the luminal surface where they are incorporated into the apical plasmalemma and the glycocalyx. There is a strong possibility that in various species some of these vesicles are involved in transcytosis of antibodies to the saliva from their source (plasma cells) in the surrounding connective tissue. In addition, vesicles may engage in transfer of growth factors from the saliva to the interstitium. In a few species, conventional SDs have been replaced by ducts that are wholly given over to secretion, i.e., they entirely lack basal striations; although such ducts occupy the histological position of conventional SDs, it is not clear whether they represent a new type of duct or merely are modifications of SDs. Broad-based comparisons of ultrastructural and other data about SDs offer some insight into evolutionary history of salivary glands and their role in the adaptive radiation of mammals. Evolutionary patterns emerged when we made interspecific comparisons across mammalian orders. Among the bats, there is a clear relationship between SD secretion and general categories of diet.

Tuft cells in the main excretory duct of the rat submandibular gland.

The fine structure of tuft cells in the main excretory duct of rat submandibular gland was investigated using the high pressure freezing and freeze substitution (HPF-FS) method and compared with that seen with both conventional chemical fixation (CF) method and en bloc treatment with ruthenium red. Some MEDs also were subjected to histochemistry for lectins. The apical vesicles and tubules of tuft cells observed by TEM after the HPF-FS method were different in shape from those treated by CF. With the first method, these vesicles and tubules, which may represent sections of a tubular system, appeared more slender and filled with a material of moderate density. A prominent glycocalyx covering the microvillar plasma membrane was observed in tuft cells processed both with the HPF-FS method and with ruthenium red. The surface of microvilli and the tubulo-vesicular structures of these cells exhibited the same soybean agglutinin (SBA) reactivity, suggesting a relationship between them.

Ultrastructure of the parotid gland in two species of naked-backed bats.

Naked-backed bats of the genus Pteronotus (family Mormoopidae) occur in the Neotropics from Mexico through northern South America. These are relatively small-sized insectivorous species that frequently roost in caves. Eight specimens of naked-backed bats (Pteronotus parnellii) were live-trapped in Suriname and one in Cuba (P. quadridens). Their parotid glands were fixed in an aldehyde mixture designed for field work and postfixed in the laboratory with osmium tetroxide. Tissues were further prepared for electron microscopy by conventional means. The parotid glands of the two species of Pteronotus closely resemble each other except for the substructure of their serous secretory granules. Serous granules in P. parnellii are bizonal, with a moderately dense inner matrix and an outer, denser corona or crescent. The matrix is occupied by laminae, flakes, and filaments in random array. In contrast, serous granules in P. quadridens consist of a uniform matrix that contains dense, usually stacked toroids or tubules either in random array or packed in bundles. A parotid gland from one specimen of P. parnellii contained an endpiece that consisted of cells that contained giant (up to 9 pm in diameter) serous granules. Serous cells in both species contain aggregates of small, uniformly dense, rod-like, membrane-delimited organelles as well as occasional bundles of cytofilaments. The endpieces are separated from intercalated ducts by a ring of granulated cells that contain secretory granules that often have a bull's-eye configuration. Intercalated and striated ducts are typical in appearance, except that many of the cells in the latter contain small, dense secretory granules in their apical cytoplasm. The parotid glands in the two species of naked-baked bats differ slightly in terms of acinar secretory granule ultrastructure, but otherwise are fairly conservative. It is thought that the glands in these particular bats might represent the "basal" condition of the salivary glands of insectivorous bats and thus can serve as a reference point for making comparisons to the highly diversified (in terms of diet) phyllostomid bats.

Ultrastructure of major intraglandular ducts in the parotid gland of the African mole-rat.

The parotid gland of a female African mole-rat, Tachyoryctes splendens, was examined by light and electron microscopy. A pure seromucous gland of conventional histology, its striated and excretory ducts contain prominent cytoplasmic inclusions that are lightly stained with toluidine blue. At the ultrastructural level, the inclusions are seen to consist of a light to moderately dense structureless matrix in which are suspended scattered, randomly oriented filaments that either are 4-7 nm or approx 14 nm thick. A few multivesicular bodies or putative lipid droplets are sparsely distributed in the inclusions. Even though the inclusions lack an encompassing membrane, all other formed cytoplasmic structures are excluded. These inclusions are not present in the ducts of the submandibular gland of the mole-rat. The inclusions may confer special properties on the parotid gland of this fossorial animal that permit it to cope with the exigencies of a subterranean existence.

The developmental role of type III and type IV cells in the rat submandibular gland.

In addition to seromucous cells and a few mucous cells (Type II cells), submandibular glands of 2-8 month old rats contain two additional cell types: type III and type IV. Type III cells contain serous-type secretory granules that sometimes have a complex substructure; type IV cells appear to be seromucous, but their granules clearly are different from those in conventional endpiece seromucous cells. Both type III and IV cells are involved in histogenesis of new endpieces in a process that differs markedly from that occurring in perinatal glands. In this process, intercalated ducts bud and give rise to immature endpieces that consist entirely of type III cells. These differentiate into type IV cells, which in turn differentiate into standard seromucous cells. Concurrently, the intercalated ducts become shorter as their most distal cells differentiate into granular duct cells. This type of developmental process begins approximately 2 months postnatally, when histogenesis of endpieces by means of terminal tubules has ended, and continues until 6 months, when its frequency sharply declines.

An unusual parotid gland in the tent-building bat, Uroderma bilobatum: possible correlation of interspecific ultrastructural differences with differences in salivary pH and buffering capacity.

The tent-building bat, Uroderma bilobatum, is a small, frugivorous phyllostomid bat with a broad neotropical distribution. Generally found in humid forest, this bat lives in small groups that create daytime "roosts" from large leaves of a variety of tropical plants. Fruit eating engenders a variety of ecological and physiological challenges for bats, some of which could require adaptive features in their salivary glands. The parotid salivary glands of Uroderma bilobatum were prepared for transmission electron microscopy by using methods that have become standard for field work. The parotid gland is extremely unusual in structure. Although the secretory endpieces still produce serous granules with a complex substructure, they are modified into quasi striated ducts. Their basal folds, which are extensive, occasionally harbor some vertically oriented mitochondria, imparting a resemblance to striated ducts. Other evidence for the endpiece origin of these parenchymal components is a well-developed system of intercellular canaliculi, structures that never occur in bona fide striated ducts. The long but sparse intercalated ducts consist of two types of cells, each of which elaborates a modest number of secretory granules of differing substructure. Striated ducts are of conventional morphology, except that a few dark cells shaped like wine glasses are present in their walls. The striated duct cells produce no secretory granules, but their apical cytoplasm may contain some small, empty vesicles. Capillaries lie in longitudinal grooves in the base of the duct cells, an arrangement that might enhance electrolyte exchange. Excretory ducts consist of simple cuboidal epithelium composed of cytologically unspecialized cells that sometimes includes a dark cell. It was concluded that salivary glands could have a major role in adapting species to acquire nutrients from marginal sources, such as tropical fruits, which have a low protein and sodium content. The unusual parotid acinar cells in Uroderma bilobatum are discussed in the context of salivary pH and buffering capacity. Comparisons are made with four other bat species, including an insectivorous species with a salivary pH > 8.0 and a very high buffering capacity, an intermediate species, and a fruit bat with acidic-stimulated saliva and very low buffering capability. Such interspecific comparisons provide a foundation for hypothesizing that ultrastructural features of the acinar cell basolateral membranes and intercellular canaliculi correlate with differences involving Na/H+ exchangers and release of HCO3- and, thus, are associated with the species differences that are important to diet and nutrient acquisition.

Intercellular material in the basal and lateral folds of parotid serous cells in four species of bats.

BACKGROUND: Basal folds are slender plications at the basal surface of acinar cells in the salivary glands of many mammalian species. These largely organelle-free folds increase the surface area of the basal plasmalemma manyfold and are unquestionably involved in the translocation of organic and inorganic molecules and water into the acinar cells. METHODS: Specimens of salivary glands were obtained from over 230 species of live-trapped bats from major areas of the globe. Tissues for electron microscopy were fixed and processed by conventional means. RESULTS: A number of the bat species examined had dense material in the intercellular spaces between basal and lateral folds of serous cells in the parotid gland. This intercellular material was particularly prominent in three species of New World bats, viz., Pteronotus parnellii, P quadridens, and Phyllostomus latifolius, and in one species of Old World bats, Chalinolobus argentatus. This dense material, which has a farinaceous texture, appears not to pass through tight junctions, so it is excluded from the lumina of intercellular canaliculi and acini. The dense material originates in the acinar cells--it is carried to the membranes of the folds via coated vesicles, which empty their dense content by exocytosis into the intercellular space. Similar dense material is present in the intercellular spaces of the basal labyrinth of striated ducts in the two species of Pteronotus. The manner in which this material accumulates in the striated duct is unclear. CONCLUSIONS: Although the function of the intracellular dense material is undetermined, it appears to be placed strategically to influence molecular traffic into acinar cells or to modulate the paracellular pathway. From a comparative evolutionary perspective, we hypothesize that, in bats, the combination of basal folds and extracellular densities is associated with insectivory. Similar morphologies appear to be lacking in frugivorous or nectarivorous species.

Ultrastructure of the binary parotid glands in the free-tailed bat, Tadarida thersites. I. Principal parotid gland.

BACKGROUND: Many species of bats have two sets of submandibular glands, principal and accessory. The accessory gland may resemble the principal one but more often shows wide morphological divergence. The free-tailed bat, Tadarida thersites, is very unusual in that it has two sets of parotid glands rather than binary submandibular glands. We studied the ultrastructure of the principal parotid gland to establish a baseline for comparison with the accessory parotid. METHODS: Two specimens of adult free-tailed bats, one male and one female, were live-trapped in western Kenya. Parotid glands were fixed for electron microscopy using a protocol expressly designed for field fixation and then embedded by conventional means. RESULTS: Histologically, the principal parotid is a typical serous gland. The secretory granules of the endpiece cells have an unusual substructure in that they contain variable numbers of lucent halos and one or several spherules. Intercalated duct cells contain a significant number of dense, serous-like granules. Striated ducts have the usual basal configuration of mitochondria and folded plasma membranes, but the supranuclear cytoplasm contains many small, dense granules, so that these ducts resemble the granular convoluted tubules found in the submandibular glands of many families of rodents. The apices of the duct cells have a peculiar contour--the luminal surfaces obliquely invaginate into the apical cytoplasm, so that in thin section the luminal membranes appear to be underlaid by a layer of vacuoles. CONCLUSION: Although the principal parotid gland of the free-tailed bat shows some distinctive, species-specific ultrastructural features, it basically is similar to the parotid gland in two other molossid bats, Tadarida brasiliensis and Molossus molossus. The distinctive features in the principal parotid gland of T. thersites might relate to its feeding on hard-bodied insects and perhaps to the production of lysozyme.

Ultrastructure of the binary parotid glands in the free-tailed bat, Tadarida thersites. II. Accessory parotid gland.

BACKGROUND: Many bat species have an extra set of major salivary glands. In some species, the accessory glands are quite similar to the principal one, but in others they may be radically different. Accessory glands usually are associated with the submandibular gland, but the free-tailed bat, Tadarida thersites, also has an accessory parotid gland. In the present study, we compared the accessory parotid gland with its principal counterpart. METHODS: Salivary glands were removed from two specimens of free-tailed bats, one of each sex, that had been live-trapped in western Kenya and immersion-fixed in a specially formulated mixture designed for field fixation. Once back in the laboratory, the tissue was further prepared for electron microscopy by conventional means. RESULTS: The secretory endpieces consist of serous tubules composed of typical serous cells that contain numerous dense granules. In contrast, the intralobular duct system shows a radical departure from normal. These ducts are enormous in caliber, their lumina measuring greater than 100 microm in diameter. They appear to arise by amalgamation of the homologues of intercalated and striated ducts into macroducts. The walls of the macroducts consist of intermingled patches of simple cuboidal and simple columnar epithelia that occasionally include a tuft cell and are underlaid by an almost continuous layer of myoepithelium. A few cells have some modified basal striations, but most cells display a cytological organization that differs radically from either of their two putative ancestral cell types. Both tall and short epithelial macroduct cells have a paranuclear collection of ovate mitochondria and aggregates of what presumably are peroxisomes. Macroduct cells in both the female and male are pervaded by a system of tubular smooth endoplasmic reticulum (SER). In the female, the SER gives rise to membranous whorls that consist of numerous plies. As the macroducts approach their termini, a single row of small dense secretory granules appears just beneath their luminal surface. At the lobular periphery, the ducts taper down to become excretory ducts of normal dimensions. CONCLUSIONS: An accessory parotid gland occurs in T. thersites, but apparently is absent in the related species, T. brasiliensis. The ultrastructural data are consistent with a possible steroidogenic function, although other features of the gland might relate to the elaboration of a secretory product associated with feeding on chitinous beetles. The macroducts conceivably function as reservoirs of preformed saliva.

Ultrastructure of the unusual accessory submandibular gland in the fringe-lipped bat, Trachops cirrhosus.

BACKGROUND: The phyllostomid fringe-lipped bat, Trachops cirrhosus, is sui generis (in a family of ca. 138 species) in that it subsists in part on tropical frogs. These amphibians frequently possess highly toxic integument. We examined the salivary glands of this bat to determine if these glands could be the source of protective factors that permit consumption of seemingly unsavory prey. The parotid and principal salivary glands of this bat are similar to homologous glands in other phyllostomids, but the accessory submandibular gland is unique. METHODS: The accessory submandibular glands of live-trapped T. cirrhosus were fixed and processed for transmission electron microscopy by conventional means. RESULTS: The accessory submandibular gland consists of follicles and ducts. The principal cells of the follicular walls have an abundance of rough endoplasmic reticulum (RER), free ribosomes, and extensive Golgi apparatuses. Typically, these cells have relatively few serous secretory granules. The ells contain collections of peculiar lipid droplets, and some of their mitochondria have dense crystalloids within expanded cristae. A layer of irregular, moderately dense bodies lies immediately subjacent to the luminal plasmalemma; it is not clear if these structures are endocytotic or exocytotic. Clusters of mucous cells, some of which have a single, hugely distended RER cisterna, are ensconced in the follicular walls; mucus from these cells reaches the lumen via intercellular canaliculi. Ducts progress from simple cuboidal to simple columnar epithelium. They lack basal striations, and their constituent cells contain relatively few mitochondria. Follicles and ducts have numerous myoepithelial cells at their periphery, and both are heavily innervated by hypolemmal nerve terminals. CONCLUSIONS: The unusual accessory submandibular gland in T. cirrhosus documents the extreme modifications in gland histology and in cell ultrastructure that have occurred in mammalian families. The cells composing the follicle walls and ducts bear little similarity to typical acinar or duct cells. Duplication of the submandibular gland in some bat lineages might be the key innovation underlying such plasticity. The heavy innervation of both follicles and ducts also implies that these structures are sensitive to and capable of responding to various inputs, perhaps including dietary factors.

Ultrastructure of the parotid salivary glands in seven species of fruit bats in the genus Artibeus.

BACKGROUND: In previous studies, we determined that the submandibular glands of five species of Neotropical fruit bats in the genus Artibeus had seromucous granules in their demilune cells with substructures that varied interspecifically in accordance with systematic relationships. Moreover, the striated ducts in these frugivores exhibited structural modifications that apparently are related to the consumption of a diet rich in potassium, but deficient in sodium. We now turn our attention to the parotid gland in a large number of species in this genus to determine if it follows the same structural pattern as does the submandibular gland. METHODS: Members of seven different species of Artibeus were live-trapped in various Neotropical locations. The parotid glands were extirpated from euthanized bats, fixed in the field, and prepared for electron microscopic examination by conventional means. The parotid glands in all seven species were virtually identical in morphology. The acinar cells (determined to be seromucous on the basis of ultrastructural criteria) contain large numbers of what appear to be vacuoles, but which are a type of secretory granule. These granules have an electron-lucent matrix and may contain one or several circular membranous profiles arranged either concentrically or in a random array. These granules appear to form by progressive dilatation of the termini of Golgi saccules, with the nascent granules finally severing their connection with the Golgi apparatus. Many of the internal membranous profiles are formed simply by invaginations of the limiting membrane of the granule; others may result from indentation of the limiting membrane by protrusions from adjacent granules; the source of multiple internal membranes in certain granules is unclear. The exocytosis of these granules results in the acinar and intercalated duct lumina being filled with an abundance of membranous material. Such extruded membranes are present in some striated ducts, but not in others, suggesting that they are degraded during passage through the duct system. The striated ducts are of conventional appearance, lacking the frondose processes that are prominent in the submandibular glands of Artibeus. CONCLUSIONS: The parotid gland in Artibeus shows none of the interspecific ultrastructural variability that characterizes the submandibular gland in bats of this genus. The seromucous acinar cells secrete granules that release phospholipids as well as glycoconjugates into the saliva. Based on the lack of frondose processes with their sodium-transporting portasomes, the striated ducts of the parotid gland are less concerned with electrolyte homeostasis than are those in the submandibular gland.

Crystalloids in the excretory ducts of the accessory submandibular gland of the long-winged bat, Miniopterus magnator.

Cytoplasmic crystalloids are abundant in the excretory ducts of the accessory submandibular gland of the long-winged bat, Miniopterus magnator. The crystalloids, which always lack a membranous enclosure, may have an intricate silhouette. They consist of parallel linear densities with a 12.5 nm periodicity. These densities actually may be thin-walled tubules. In some crystalloids, intersecting subcrystalloids produce a complex pattern of decussate densities. In a few rare instances, continuities were detected between a crystalloid and a smooth-surfaced cisternal element. In other mammalian species, similar crystalloids connected to smooth endoplasmic reticulum play a role in steroid metabolism. We postulate that the ductular crystalloids in M. magnator might be involved in production of a factor that influences mating behavior.

Hyperimmunoglobulinemia D in idiopathic retinal vasculitis.

BACKGROUND: We examined four patients who exhibited both idiopathic retinal vasculitis and elevated serum IgD levels. Uveitis caused by Behçet's disease is also associated with high levels of serum IgD. Therefore, the clinical features of these patients were investigated and the possible relationship between retinal vasculitis and elevated serum IgD was examined after undertaking a study of increased IgD levels in patients diagnosed with uveitis. METHODS: The study population was composed of 110 patients: 49 with Behçet's disease, 15 with sarcoidosis, 10 with Vogt-Koyanagi-Harada disease, and 36 with other forms of uveitis. IgD measurements were performed using modifications of the latex photometric immunoassay. Surface IgD (sIgD) expression in peripheral lymphocytes was determined by immunofluorescence, and the correlation between serum IgD levels and the percentage of sIgD-positive cells was examined. RESULTS: Twelve of the 110 patients had an elevated serum IgD. Eight of the 12 had Behçet's disease, and 4 were diagnosed with idiopathic retinal vasculitis. These 4 patients were HLA-A24+ females whose ages ranged from 8 to 25 years. A linear correlation between the serum IgD levels and the percentage of sIgD-positive cells was found. CONCLUSION: Hyperimmunoglobulinemia D state was found in Behçet's disease and idiopathic retinal vasculitis. These diseases may represent a new clinical entity characterized by signs of retinal vasculitis and hyperimmunoglobulinemia D that results from abnormal B cell activation and immune complex-mediated responses.

Megamitochondria in the serous acinar cells of the submandibular gland of the neotropical fruit bat, Artibeus obscurus.

BACKGROUND: As part of a continuing investigation of the comparative ultrastructure of chiropteran salivary glands, we examined the submandibular glands of eight species of neotropical fruit bats in the genus Artibeus. We previously described secretory granules of unusual substructure in the seromucous demilunar cells of this organ in some species in this genus. In the present study, we turned our attention to the serous acinar cells in the same glands. METHODS: Specimens of eight species of Artibeus were collected in neotropical localities. Salivary glands were extirpated in the field and thin slices were fixed by immersion in triple aldehyde-DMSO or in modified half-strength Karnovsky's fixative. Tissues were further processed for electron microscopy by conventional means. RESULTS: In contrast to seromucous cells, which exhibit species-specific diversification in bats of this genus, the secretory apparatus and secretory granules in the serous acinar cells are highly conserved across all seven species. The single exception involves the mitochondria in one species. In this instance, some of the serous cell mitochondria in Artibeus obscurus are modified into megamitochondria. Such organelles usually have short, peripheral cristae; a laminar inclusion is present in the matrix compartment of every outsized organelle. Inclusions of this nature never are present in normal-size mitochondria in the serous cells. None of the megamitochondria were observed in the process of degeneration. CONCLUSIONS: The giant mitochondria in A. obscurus have a matrical structure that is radically different from that of the only other megamitochondria reported to occur in bat salivary glands. The factors that lead to variation in megamitochondrial substructure in different species, as well as the functional capacities of such giant organelles, are unknown.

Ultrastructure of the parotid gland in the common vampire bat, Desmodus rotundus, with special emphasis on oncocytes.

The parotid gland of the common vampire bat, Desmodus rotundus, is a pure seromucous gland. Typical acinar cells have a complement of secretory granules with a light matrix and one or several spherules and ancillary densities. These cells also contain mitochondria of conventional appearance. Mixed in with these acinar cells are cells that fulfil all of the ultrastructural criteria for identification as oncocytes. They contain enhanced numbers of mitochondria that frequently display peculiarities in the number and disposition of their cristae. The oncocyte mitochondria are closely packed and often are joined by periodic bridges. Most of the cells in the intercalated ducts are cytologically unremarkable; a few scattered duct cells have a single, grossly distended cisterna of rough endoplasmic reticulum that contains a homogeneous material of moderate density. The intercalated ducts are succeeded by ducts that lack the usual basal striations, but that consist of cells with numerous, small, dense granules. These secretory ducts probably are the homologues of striated ducts in parotid glands of other species. The structure of these ducts in the parotid gland in the vampire bat suggests that this gland does not play a homeostatic role in the regulation of electrolytes, a role that appears to be carried out in this bat in the submandibular glands, but that its major intralobular ducts contribute substantial quantities of organic material to the saliva.

A unique parotid gland in Hart's little fruit bat, Enchisthenes hartii.

BACKGROUND: Hart's little fruit bat, Enchisthenes hartii, is uncommon and, although it has been the subject of recent molecular genetic studies, is little known biologically. Because chiropteran salivary glands vary interspecifically in ways that reflect evolutionary history and ecology, we examined the parotid gland in E. hartii to ascertain the extent to which it resembles homologous glands in species to which this bat presumably is related. METHODS: The parotid glands were prepared for electron microscopic examination by conventional means. RESULTS: The parotid gland of E. hartii is structurally unique among all previously studied species of bats (> 230 species examined) and other mammals. In contrast to the same gland in other mammals, the parotid gland in E. hartii lacks secretory endpieces. In their place, there is a type of striated duct. Thus, in this species single secretory elements consist of (proceeding in the direction of salivary flow): striated duct--intercalated duct--and a conventionally located striated duct. The proximal ducts possess microvillus-lined intercellular canaliculi, whereas the walls of the distal ducts include occasional dark cells. Some small serous-like granules may be present in the intercalated duct cells. CONCLUSIONS: The function(s) and biological role of the unique parotid gland in E. hartii are unknown. Nevertheless, the presence of two sets of striated ducts provides two separate glandular components seemingly capable of electrolyte transport. This might be of adaptive significance in enabling this species to make use of tropical nutrient resources that otherwise would be unavailable. The uniqueness of its parotid glands lends support to the current hypothesis that E. hartii should be classified as a monotypic genus rather than as a species of Artibeus, whose members it resembles morphometrically.