Histology and histochemistry of the major salivary glands in the southern white-breasted hedgehog (Erinaceus concolor)

This study aimed to investigate the major salivary glands in the southern white-breasted hedgehog (Erinaceus concolor) histologically and histochemically. Five adult males were included in this study. The results showed that anatomically the shape of the parotid, submandibular and sublingual glands of the Erinaceus concolor was respectively almost pear, elliptical to pyramidal and oval. Histologically, the parotid gland had serous acini and secretory cells showed negative reaction to alcian blue (AB) (pH = 2.5) and negative response to aldehyde fuchsin (AF), methylene blue (MB) and PAS stains. The submandibular gland was a mixed gland of mucous and serous acini. The mucous acini were strongly positive for PAS, AB, MB and AF. However, serous acini were week for PAS and negative against AB, MB and AF stains. The sublingual gland was purely composed of mucous acini. The mucous acini of the sublingual gland were strongly positives for PAS, AB and MB methods. While their reaction to the AF staining was negative. In conclusion, the histological and histochemical observations of the major salivary glands of the southern white-breasted hedgehog (E. concolor) indicated that these glands shown similarities and some special different histochemical features as compared to other mammalian species.     

Histological and histochemical characterization of the mucosa of the digestive tract in flower fish (Pseudophoxinus antalyae)

The wall of the digestive tract is composed of the tunica mucosa, tunica muscularis and tunica serosa. Lamina-submucosa separation or any glands were not observed in tunica mucosa. Goblet cells were determined to constitute a much larger reserve at digestive tract mucosa. Histochemical analysis of the intestine of flower fish (Pseudophoxinus antalyae) showed that gastrointestinal mucous content included sulphate-esters and/or carboxylic [Alcian blue (AB) 0.06+], glycogene and/or oxidable dioles [periodic acid/Schiff+ (PAS+)], neutral or acid-rich (PAS/AB pH 2.5+), sialic acid residues (KOH/PAS) and strong acid sulphated [Aldehyde fuchsin+ (AF+)] glycoproteins (GPs). Except these mucosubstances to lower densities, densely sulphate (AB pH 2.5+), O-sulphate esters (AB pH 1+) strong and weak sulphated (AB 0.3 M+), GPs were also determined.     

Gill epithelium of an angler catfish,Chaca chaca (Siluriformes,Chacidae): Enzyme and glycoprotein histochemistry

A series of histochemical techniques have been employed to localize alkaline phosphatase, acid phosphatase, non-specific esterase, catalase and peroxidase; and to visualize and characterize glycoprotein (GPs) moieties in the epithelium of gill arch, gill filaments and secondary lamellae of an angler catfish Chaca chaca. The epithelium of gill arch and gill filament shows strong alkaline phosphatase activity in the deeper layer epithelial cells; strong non-specific esterase activities in the outer layer epithelial cells; and weak acid phosphatase activity throughout the epithelium. The activity of these enzymes in the secondary lamellae is weak. The catalase and peroxidase show strong activities in the blood cells of the secondary lamellae. Various classes of GPs have been identified and characterized in the mucous secretions of the gill epithelium of C. chaca. These include—GPs with oxidizable vicinal diols, GPs with sialic acid residues without O-acyl substitution and GPs with O-sulphate esters. The functional significance of different enzymes in gill epithelium and the GPs in the mucus secreted on the surface has been discussed with the physiology of the gills in relation to the characteristic habit and habitat of the fish.     

Histomorphometric and histochemical characteristics of the oesophagus of the greater mouse-eared Bat,Myotis myotis (Borkhausen, 1797)

The aim of this study was to examine the histomorphometric and histochemical structure of oesophagus of the wild-caught greater mouse-eared bat M. myotis. For this purpose, 10 specimens of oesophagus were collected and processed. The oesophagus wall of M. myotis is composed of four layers: tunica mucosa, tunica submucosa, tunica muscularis and tunica adventitia. The mucosa is covered by a non-keratinized stratified squamous epithelium. There were no glands in the wall of the oesophagus. Tunica muscularis is composed of two muscle layers: internal circular muscular layer and an external longitudinal muscular layer. Histochemical studies revealed that the oesophagus was AB/PAS and PAS positive indicating the presence of acidic and neutral mucosubstances. AB-PAS staining shows that glycoproteins were predominant in the all examined layers of the oesophagus. Because of the absence of oesophageal glands in M. myotis, positive reaction with AB-PAS staining may be due to secretion of salivary glands. Absence of oesophageal glands reflects the functional adaptation as high food passage rate for the insectivorous feeding habits of animals.     

Ultrastructure and histochemical study of glycoconjugates in the gills of the white croaker (Micropogonias furnieri)

The ultrastructure of the primary and secondary lamellae of gills was investigated in a marine teleost, the white croaker. The following cells were identified and briefly described: pavement cells, mucous cells, mitochondria-rich cells and rodlet cells. These cell types are present throughout the length of the lamellae. They are studied by means of a series of carbohydrate histochemical methods, including lectin procedures. Neutral sugars and substituted sialic acid were detected by means of periodic acid-borohydride reduction-saponification-periodic acid Schiff reaction (PA/Bh/KOH/PAS), saponification-selective periodic acid Schiff reaction (KOH/PA*S) and saponification-selective periodic acid-borohydride reduction-periodic acid Schiff reaction (KOH/PA*/Bh/PAS) histochemical techniques. A battery of seven lectins was used to study binding on tissue sections at the light microscopic level to characterize glycoconjugates in gills. The reaction to Canavalia ensiformis agglutinin (Con-A), Triticum vulgaris agglutinin (WGA), and Ricinus cummunis agglutinin-1 (RCA-1) was weak in pavement cells; unlike Con-A, the reaction to WGA and RCA-1 was more intense in mucous cells. Arachis hypogaea agglutinin (PNA) lectin showed a strong reaction in mucous cells. Ulex europaens agglutinin-1 (UEA-1) lectin was negative in all cell types. The lectin pattern was similar for both primary and secondary lamellae, except for PNA reaction, which was weak in the pavement cells of the secondary lamella and negative in the pavement cells of the primary lamella.     

Amoeba‐like Infections in Cultured Marine Fishes: Systemic Infection in Pompano Trachinotus falcatus L. from Singapore and Gill Disease Associated with Paramoeba sp. in Sea Bream Sparus aurata L. from Greece

Two cases of Amoeba‐like infections in cultured warmwater marine fish are described, an unusual systemic infection in pompano Trachinotus falcatus L. from Singapore and a gill infection in Mediterranean sea bream Sparus aurata L. All pompano showed marked systemic infection of Amoeba‐like parasites in gills, kidney, intestine, pancreas and spleen. The most severe lesions were in the gills and renal tissue with minimal tissue reaction in other organs.     

Distribution and Characterisation of Goblet Cells in the Large Intestine of Ostriches during the Pre‐ and Post‐Hatch Period

The role of goblet cell secretion, containing mucopolysaccharides, in the formation of a protective barrier of intestinal mucosa and transportation of the intestinal content has been described quite extensively. However, information on the quality composition of mucopolysaccharides and its changes in the intestinal tract of ostrich chicks, especially in the large intestinal segments, is unavailable. In the current study, ostrich embryos/chicks (n = 6/36) of both sexes were used shortly before hatching and during the first months of the post‐hatch period. Tissues for histology were taken from the large intestine: the medium segments of the caecum, proximal and distal parts of colon. By using histochemical reactions, the differentiation of goblet cells as well as chemical composition of mucopolysaccharides was carried out. The cells contained acid (AB+), neutral (PAS+) and mixed (AB/PAS+) mucopolysaccharides. The number of goblet cells in the large intestine per unit area of mucosa increased towards the cloaca, and it was the highest in the distal part of the colon. The qualitative goblet cell composition in different large intestinal parts was different in all ages. In the caecum, goblet cells containing acid and mixed mucopolysaccharides dominate post‐hatch, whereas in the colon, goblet cells containing acid mucopolysaccharides predominated. The most rapid changes in the qualitative goblet cell composition occur during the first week post‐hatch when in all the intestinal segments the proportion of cells containing acid mucopolysaccharides continuously increased.     

The histology and histochemical aspects of gills of the flower fish, <Emphasis Type="Italic">Pseudophoxinus antalyae</Emphasis>

Branchial epithelium of Pseudophoxinus antalyae was lined by both a thick stratified epithelium lining gill arches, gill rakers and primary filaments and a thin epithelium lining the lamellae. Mucous, chloride and rodlet cells, interspersed between pavement cells, were present in the branchial epithelium. With histochemical procedures for the characterization of glycoconjugates, mucous cells showed a strong positive reaction with Periodic acid-Shiff and Alcian Blue at pH 2.5, although with Alcian Blue at pH 0.5 and pH 1.0 the reaction was much weaker. When the combined Alcian Blue (pH 2.5) – Periodic acid-Shiff reaction was performed, most mucous cells were stained purple, whereas by the combined Aldehyde Fuchsin/Alcian Blue (pH 2.5), most cells showed a positive reaction only to Aldehyde Fuchsin. Methylation/ Alcian Blue (pH 2.5) and Methylation/ Saponification/ Alcian Blue (pH 2.5) methods showed the presence of sulphated and carboxylated glycoconjugates in mucous cells. Mucous cells were also detected to stain all metachromatically with Toluidine Blue.     

Ultrastructural characterization of gills in juveniles of the Argentinian Silverside, Odontesthes bonariensis (Valenciennes, 1835) (Teleostei: Atheriniformes)

An ultrastructural study was performed on the gills of juvenile Argentinian silverside, Odontesthes bonariensis. The gills are composed of two sets of four holobranchs and, in turn, each holobranch consists of a gill arch and two rows of caudolaterally projecting branchial filaments. From the dorsal and ventral surfaces of each filament, branchial lamellae radiate out as foldings of the epithelial layer. Gill rakers are present on each of the gill arches, on the anteromedial side of the arch opposite to the filaments. Gill rakers, gill arches and branchial filaments are covered by a stratified epithelium, whereas branchial lamellae essentially consist of a thin epithelial envelope containing capillaries. In the stratified epithelium, mucous cells, rodlet cells, granular cells, pavement epithelial cells and mitochondria-rich cells are identified. The thin epithelium that lines the lamellae comprises two cell types, outer and inner epithelial cells, and the capillary walls on the inside of the epithelial envelope are defined by pillar cells. The ultrastructure of all these cell types is described and our findings are discussed in light of the existing data on fish gill morphology. In the gills of juvenile Argentinian silverside is of particular interest the characteristics showed by mitochondria-rich cells, such as their arrangement in clusters of 2-3 cells and their small and depressed surface in contact with the aquatic milieu, features which strongly resemble those of euryhaline species.     

Mucous Cells in Micropogonias furnieri gills: Histochemistry and Ultrastructure

The characteristics of the mucous cells located in the gills of the fish Micropogonias furnieri were investigated. Using histochemical procedures that included methods for localization and characterization of glycoproteins (GPs), no differences were detected between the mucous cell contents of the primary and secondary lamellae. The GPs were identified with (a) oxidizable vecinal diols; (b) sialic acids and some of their chain variants, C7 or C9; (c) carboxyl groups and (d) sulphate groups. The electron microscope showed large mucous globules of different electro densities from mucous cells located deep in the epithelium between the other epithelial cells; the release of mucus by exocytosis was observed. GPs secreted on the surface of the mucous cells was suggested to be important for the lubrication, protection and inhibition of microorganisms. It is possibility that GPs could have similar roles in Micropogonias furnieri gills.     

Communications: Metastatic Gill Lesions Secondary to Cardiac Hemangioendotheliosarcomas in the Teleost Fish Mangrove Rivulus

Abstract

Gill neoplasms have been infrequently described for teleost fishes. Nine of 51 cases of primary cardiac endothelial cell neoplasms of a teleost fish species, mangrove rivulus Rivulus marmoratus, also possessed endothelial cell neoplasms in their gills. These neoplasms occurred in the afferent arterioles of the gill filaments. They were made up of round cells or spindle cells that had nuclei similar to typical endothelial cell nuclei. The large gill neoplasms, with more anaplastic cells, penetrated the walls of the gill arterioles and invaded adjacent gill tissues. Supporting evidence for the metastatic nature of these gill neoplasms includes the following: (1) they were secondary in timing, numbers, and size to the advanced sarcomas of the heart; (2) cell phenotypes of both gill and cardiac neoplasms were similar in cytoplasmic and nuclear features; (3) the cardiac neoplasms appeared to be shedding neoplastic endothelial cells into the lumen of the bulbus arteriosus with a direct route via the circulation of the ventral aorta to the afferent arterioles of the gills; and (4) direct evidence that the gill neoplasms arose from gill endothelium was lacking.     

Ultrastructural Alterations in the Gills of Labeo rohita Fingerlings Exposed to Thermal Extremes

This study aimed to determine the cellular alterations in the gill of Labeo rohita exposed to lethal temperature maxima (LT_Max) and lethal temperature minima (LT_Min) by means of transmission electron microscopy (TEM). Acclimation of advanced fingerlings of L. rohita was carried out at 26°C for 30 days. Acclimated fish were subjected to a constant rate of increase or decrease in temperature (0.3°C/min) until the LT_Max and LT_Min values were reached. Dissected gills were processed for TEM, both at the end of acclimation period at ambient temperature (26°C) and at lethal temperatures. Results indicated that at ambient temperature, the gill tissues appeared normal. However, significant changes were observed at lethal temperatures. The gill tissues at lethal temperature maxima showed severely damaged lamellae, with more vacuolated space. At lethal temperature minima, gill tissues showed increased density of mitochondria. Our prima‐facie report indicated that L. rohita exposed to lethal temperatures exhibited marked ultrastructural changes in the gills.     

Proliferative Gill Disease of Fish from the Tennessee-Tombigbee Waterway,Mississippi

Abstract

Proliferative gill disease (PGD), a condition not previously reported in wild fish, was found in two channel catfish Ictalurus punctatus sampled from the Tennessee-Tombigbee Waterway in Mississippi during June and July 1989. The parasite thought to cause PGD was observed in only one of the fish, but the distinctive lesions associated with this disease were prominent in both of the channel catfish. Organisms resembling the PGD parasite were also found in the gills of 4 of 18 largemouth bass Micropterus salmoides and 6 of 20 bluegills Lepomis macrochirus, but there was little or no host response to these parasites.     

半滑舌鳎免疫球蛋白对黄芪多糖的免疫应答

采用单因素6水平3重复的试验方法,研究半滑舌鳎免疫球蛋白对黄芪多糖(APS)的免疫应答水平变化,确定半滑舌鳎免疫球蛋白对APS产生最强免疫应答时的APS最佳添加剂量。结果表明,随着试验时间的延长,试验组半滑舌鳎鳃黏液、肠黏液、血液及皮肤黏液免疫球蛋白对APS的免疫应答水平呈先升高后降低的变化趋势,且均显著高于对照组(P<0.05),皮肤黏液免疫球蛋白含量在第18 d时达到最高水平,鳃黏液、肠黏液和血液中的免疫球蛋白含量则于第54 d时达到最高水平;随着APS添加剂量的增加,试验组半滑舌鳎血液、皮肤黏液、鳃黏液及肠黏液免疫球蛋白对APS的免疫应答水平呈逐渐升高的变化趋势,且大部分显著高于对照组(P<0.05);半滑舌鳎鳃黏液、肠黏液、血液及皮肤黏液免疫球蛋白对APS产生最强免疫应答时的APS最佳添加剂量为1 800 mg/kg。     

Effects of diet on acidic and neutral goblet cell populations in the small intestine of early weaned pigs.

Effects of dietary manipulation on Alcian blue-positive (AB+) and periodic acid-Schiff-positive (PAS+) goblet cell populations were determined for the villi and intestinal crypts in the small intestine of early weaned pigs. Pigs were weaned at 21 days of age and samples from the distal portions of the duodenum and the middle and distal portions of the jejunum were obtained when pigs were 21, 24, 27, 30, 33, and 36 days old. Pigs were assigned to 1 of 3 dietary treatments; all diets contained 20% protein, on the basis of hydrolyzed casein, soybean meal, or corn-soybean meal. By day 24, three days after weaning, the populations of AB+ and PAS+ goblet cells were markedly decreased, regardless of diet. Goblet cell populations in the villi tended to increase from 3 to 15 days after weaning, whereas those in the intestinal crypts remained low throughout the study. Differences between any of the dietary treatments were not apparent for AB+ or PAS+ goblet cell populations in the villi or in the intestinal crypts. It appeared that early weaning per se, and not diet, was the primary cause for decreases in goblet cell populations.     

Oestrus Synchronization Treatment Induces Histomorphological Changes on the Uterine Tube Epithelium of the Gilt

The aim of this study was to determine the histomorphological changes that occurred in response to two treatments for oestrus synchronization in three different regions of the gilt's uterine tubes epithelium: the ampulla (AMP), ampulla–isthmic junction (AIJ) and isthmus (IST). Nine prepuberal gilts were divided into three groups (n = 3): (1) eCG 400 IU and hCG 200 IU (eCG/hCG), (2) progesterone agonist (P4) and (3) control group. The number of secretory cells (stained with periodic acid–Schiff reaction or PAS‐positive cells) decreased in the AMP in the P4 treated group when compared to the control group, whereas, no difference was observed in the number of PAS‐negative cells in the AMP of the three groups. A significant decrease in the number of PAS‐positive cells was observed in the AIJ and IST of the P4 treated group when compared to the eCG/hCG and control groups. An increase in the number of PAS‐negative cells was observed in the AIJ and IST in the P4 treated group. The epithelium height in the AMP and AIJ was increased in the eCG/hCG group when compared to the control and P4 groups. In this last group, we observed a reduced height compared with the other two groups for the AIJ. In the IST, there were no significant changes in the epithelium height of the control or the other two groups (eCG/hCG and P4). The epithelial cells of the P4 treated group had the least amount of cytoplasmic granules and the lowest intensity of PAS staining in the AMP, AIJ and IST. Animals treated with eCG/hCG showed an intermediate number of cytoplasmic granules and intensity in all regions evaluated. These data show that P4 treatment for synchronization induces a significant (P < 0.001) decrease of PAS‐positive cells and staining intensity of cytoplasmic granules in the different regions studied and an increased number of PAS‐negative cells in the AIJ and IST epithelium. Moreover, eCG/hCG treatment increased the height of the epithelium in the AMP and AIJ, while in this last region, the P4 treatment decreased the epithelium height. These results show that synchronization treatments with P4 and in a smaller proportion with eCG/hCG can modify the amount of PAS‐positive and PAS‐negative cells, and the epithelium height. This has influence in the secretory activity of the epithelium and possibly alters the fluid microenvironment of the gilt's uterine tube. The biological impact of regional variations in the epithelial cells of the gilt′s uterine tube needs further investigation to understand the implications that the reproductive processes can have in the uterine tube.     

Histology and histochemistry of the pharyngeal cavity and oesophagus of the silverside Odontesthes bonariensis (Cuvier and Valenciennes)

The histology of the pharyngeal cavity and oesophagus of the freshwater 'silverside'Odontesthes bonariensis (Cuvier and Valenciennes) and the characteristics of their mucous cells were investigated. The histological characterization of its digestive wall revealed that the mucosa is thrown with longitudinal folds. The epithelium covering the folds was stratified with abundant mucous cells and gustative corpuscles, which are lacking in the oesophagus. The muscularis mucosa was absent. The submucosa presented the compactum stratum. The muscularis was organized in longitudinal and circular layers of muscular striated fibres. The serosa with a flat epithelium was located only in the oesophagus. Using histochemical procedures including methods for localization and characterization of glycoproteins (GPs), no differences were detected between the mucous cells contents of the pharyngeal cavity and those of the oesophagus. The mucous cells showed a weak periodic acid-Schiff (PAS) positive reaction in their content. The reactions for the differential analysis of sialic acids from GPs are feeble for periodic acid-Schiff at low temperature and low pH (PA*S) and KOH/PA*S and strong for periodic acid/borohydride/KOH/PAS (PA/Bh/KOH/PAS) and KOH/PA*/Bh/PAS revealing the scarce presence of C7 or C9 substituted and non-substituted sialic acids and the abundance of C7, C8 substituted sialic acids, O-acyl sugars and neutral sugars respectively. The results suggest that the pharyngeal cavity with the gustative corpuscles would induce the gastric secretion whereas the oesophagus is mainly involved in the transport of the food bolus to the stomach with the aid of abundant secretion of mucus. GPs secreted on the surface of the mucous cells, likely related to environmental conditions, would be involved in the lubrication, protection against abrasion and inhibition of microorganism proliferation.     

Ultrastructural examination of the host cellular response in the gills of Atlantic salmon, Salmo salar, with amoebic gill disease

Gills from Atlantic salmon with experimentally induced amoebic gill disease (Neoparamoeba spp.) were examined with transmission electron microscopy to assess pathology and host-cell responses. Amoebae were found either on the surface epithelium or with pseudopodia extending deeply into invaginations of epithelial cells. The amoebae had various densities along the plasma membrane and contained electron-dense deposits within their cytoplasm. Surface epithelial cells sloughed from the gills and had features consistent with apoptosis, including rounded shape, loss of surface microridges, and hypercondensation of nuclear chromatin. Affected areas of gills had fusion of secondary lamellae with interlamellar spaces occupied by mitotic epithelial cells and eosinophils. Eosinophils contained abundant fusiform-shaped granules that measured approximately 1 microm long and 360 nm wide. The granule consisted of an electron-dense matrix with a central inclusion that was less electron-dense, consisting of particulate and fibrillar material. In many instances, the central inclusion appeared empty and 90% of the eosinophils had morphology suggestive of piecemeal degranulation. Also observed within affected areas were a few neutrophils, mucous cells releasing mucus, and a small number of dendritic-like cells.     

Effects of glucagon‐like peptides 1 and 2 and epidermal growth factor on the epithelial barrier of the rumen of adult sheep

Epidermal growth factor (EGF) and glucagon‐like peptides (GLP) modulate the tight junctions (TJ) of the intestinal epithelial barrier (EB) of monogastric animals. This work tried to elucidate whether GLP‐1, GLP‐2 and EGF can affect the EB of the rumen. Ovine ruminal epithelia were incubated in Ussing chambers for 7 hr with 25 or 250 nM of either GLP‐1 or GLP‐2 on the serosal side, with 2.5 nM of EGF on the serosal side or with 0.25 or 2.5 nM EGF on the mucosal side. No treatment affected tissue conductance. Short‐circuit current (I_sc) was affected by time and treatment and their interactions. Only 250 nM of either GLP‐1 or GLP‐2 decreased I_sc in certain periods compared with 25 nM GLP‐1 or 0.25 nM mucosally applied EGF; however, not when compared to control epithelia. Fluorescein flux rates (J_fluor) of ruminal epithelia were affected by treatment, time and time × treatment interaction. The time × treatment interaction was based on an increase in J_fluor between the first and last hour in epithelia incubated with 25 nM GLP‐1 or GLP‐2 and in epithelia incubated with EGF. After 7 hr incubation, claudin‐7 mRNA expression was downregulated in all treatments. Claudin‐1 mRNA was upregulated after incubation with 2.5 nM EGF on the serosal side, claudin‐4 mRNA was downregulated by 2.5 nM EGF on the mucosal side, and occludin mRNA was increased after incubation with 250 nM GLP‐2. The protein abundance of all tested TJ proteins was not influenced by treatment. We conclude that GLP‐1, GLP‐2, and EGF have no obvious acute effects on the EB of ruminal epithelia under simulated physiological conditions ex vivo. However, by decreasing the mRNA expression of claudin‐7 and partly affecting other TJ proteins, they may modulate EB in the longer term or under certain conditions.     

Clinical and Pathological Effects of the Polyopisthocotylean Monogenean,Gamacallum macroura in White Bass

Abstract

An aquaculture research facility experienced high mortality rates in white bass Morone chrysops associated with a monogenean infestation of the gills, but not in striped bass Morone saxatilis in the same facility. All mortalities had pale gills. Monogeneans, identified as Gamacallum macroura (MacCallum and MacCallum 1913) Unnithan 1971, were found on the gills. Pale-gilled and healthy white bass were selected with no particular attention to condition for venipuncture and euthanasia for postmortem examination, including parasite counts from gills. The median packed cell volume (PCV) of fish with gill pallor was 12.5% (range 9–37%) while PVC of fish with more normal color was 30% (27–33%). Association between the PCV and gill pallor score was statistically significant, as was the association between PCV and the number of monogeneans found on the gills of each fish. Median estimated white blood cell count of fish with gill pallor, at 12.05 × 10^3/μL (range 3.8–24.7), was significantly lower than of apparently healthy fish: 24.7 × 10³/μL (17.3–31.5). Histopathology of the gill arches of pale-gilled fish revealed multifocal moderate to severe branchitis, focal areas of dilated hyperplastic lamellae occluded by fibrin, and monogeneans attached to the lamellae. Fish that were apparently healthy had grossly similar histologic lesions, but at lower frequency and severity.

Received May 27, 2011; accepted July 12, 2012