A study of the histology of the digestive tract of the Nile tilapia

The digestive tract of Oreochromis niloticus is described, in order to resolve discrepancies found between previous accounts. Two types of goblet cells were found in the oesophagus, which differed in size, and in staining characteristics with periodic acid-Schiff and alcian blue. A region with tubular glands consisting of large mucous cells was continuous from the entry of the oesophagus, across the anterior part of the stomach to the pyloric valve, essentially providing a bypass circumventing the sac-like portion of the stomach. This region, which is lined with striated muscle, may be a means of disposing of unwanted material, either by regurgitating it, or by passing it rapidly along to the intestine. Large mucus cells in the tubular glands and the neck cells of the gastric glands probably protect the mucosa from the very acid contents of the stomach. An ileorectal valve was present. There is therefore a separate intestine and rectum in O. niloticus , as in most teleosts.     

Histochemistry of the utero-vaginal junction with special reference to the sperm-host glands in the oviduct of the domestic duck.

The "utero-vaginal junction" that connects the uterus and vagina of duck oviduct differs histologically and histochemically from the adjacent zones. The region is characterised by low, somewhat longitudinally arranged mucosal folds, lined by tall columner cilliated cells with apical nuclei alternating with mucous secreting goblet cells containing basal nuclei. Within the propria of the mucosa there are numerous tubular glands--the sperm host glands--which are responsible for sperm storage after copulation. The goblet cells of the utero-vaginal junction contain an admixture of neutral, sulfated and nonsulfated acid mucopolysaccharides, while the sperm host glands are devoid of any mucopolysaccharide and secrete complex lipoidal materials and exhibit intense acid phosphatase activity. The functional significance of the secretory materials of the sperm host glands have been discussed in the light of sperm release mechanism.     

Histological and ultrastructural study of the digestive tract of rice field eel, Monopterus albus

The histological characteristics of the digestive tract and the ultrastructure of mucosal cells of the stomach and intestine of rice field eel, Monopterus albus, are described to provide a basis for future studies on its digestive physiology. The digestive tract of the rice field eel is a long and coiled tube composed of four layers: mucosa, lamina propria‐submucosa, muscularis and serosa. The pharynx and oesophagus mucosa is lined with a stratified epithelium. The stomach includes the cardiac and pyloric portions and the fundus. Many gastric pits are formed by invaginations of the mucosal layer and tubular gastric glands formed by the columnar cells in the fundus. The intestine is separated from the stomach by a loop valve and divided into a proximal portion and a distal portion. The proximal intestinal epithelium consists of columnar cells with microvilli towards the lumen and goblet cells. The enterocytes are joined at the apical surface by the junctional complex, including the evident desmosomas. Numerous lysosomes and some vesicles are evident in the upper cytoplasm of the cells, and a moderate amount of endoplasmic reticulum and lysosomes are scattered in the supranuclear cytoplasm. The epithelium becomes progressively thicker and the folds containing large numbers of goblet cells are fewer and shorter in the distal portion of the intestine. At the ultrastuctural level, the columnar cells of the tubular gastric glands have numerous clear vacuoles and channels. A moderate amount of pepsinogen granules are present in the stomach. The enterocytes of the intestinal mucosa display a moderate amount of endoplasmic reticulum and lysosomes, and long and regular microvilli.     

The gallbladder of the Capivara Hydrochoerus hydrochoeris (Mammalia: Rodentia)

The authors studied morphological and histochemically the mucopolysaccharides and proteins in the gallbladder tubular glands and epithelial cells of the capivara Hydrochoerus hydrochoeris. Based on the results the authors concluded: 1. the gallbladder single columnar epithelium consists of secretory, migrating, and goblet cells; 2. in the lamina propria are single coiled tubular glands; 3. goblet and tubular gland cells show neutral and sulphated mucopolysaccharides and sialic acid; 4. columnar cells show neutral mucopolysaccharides and protein radicals; 5. migrating cells show only protein radicals.     

Morphological, micromorphological and histochemical studies on the parotid salivary glands of the one-humped camel (Camelus dromedarius).

The morphology, blood and nerve supply of the parotid salivary glands of the one-humped camel were studied in detail. The intraglandular portion of the duct system was also examined. The histological and histochemical studies showed that the parotid salivary glands of the camel are of the tubuloacinar type and are serumocoid in nature. The secretory acini and tubules show themselves in 3 different forms according to the different phases of their secretory cycle. The duct system of the gland contains goblet cells between its lining epithelium. The intercalated ducts show ampullation followed by narrowing that help in mixing the secretion. Intraepithelial glands are found in the terminal part of the parotid duct.     

Morphology of the nasal fossae and associated structures of the hamster (Mesocricetus auratus)

The hamster nasal cavity consists of vestibular, non-olfactory and olfactory portions. Much of the non-olfactory nasal cavity surface is lined by cuboidal, stratified cuboidal, and low columnar epithelia, devoid of cilia. Goblet cells and ciliated respiratory epithelium are present over only a small portion of the nasal cavity surface. The largest glandular masses in the hamster nose are the maxillary recess glands, the vomeronasal glands and the lateral nasal gland 1; these three glands contain neutral mucopolysaccharides (PAS-positive). Other nasal glands contain both acidic and neutral mucopolysaccharides; the staining reaction for acidic mucopolysaccharide is stronger in goblet cells and olfactory glands than in the other nasal glands. The ducts which open into the nasal vestibule are the excretory ducts of compound tubuloacinar serous glands. The one major PAS-positive gland whose duct opens into the nasal vestibule is the lateral nasal gland 1. The ducts of the compound tubuloacinar vomeronasal glands open into the lumen of the vomeronasal organ, which is connected to the ventral nasal meatus by means of the vomeronasal duct. The ducts of the branched tubuloacinar maxillary recess glands open into the maxillary recess. Few ducts open into the caudal half of the nasal cavity.     

Distribution of epithelia and glands of the nasal septum mucosa in the rat.

A histotopographic study of the nasal septum mucosa in rats was made using semi-serial sections stained with PAS-hematoxylin, reconstructed in form of maps representing the structure in a sagittal plane. The stratified squamous, respiratory and olfactory epithelia and Masera's organ cover 14.8, 43.6, 41.6 and 1.8%, respectively, of the septal surface (117.1 mm2). In the vestibular region, only ducts of PAS-negative glands of the respiratory region are found, and below the septum there is the infraseptal gland with PAS-negative acini. In the respiratory region, PAS-negative acinous glands form two groups: the superior and the inferior one occupying 10.5 and 1.5%, respectively, of the septal area. PAS-positive acinous glands are in the inferior half of the respiratory region and in a small anteroinferior portion of the olfactory region. Besides goblet cells broadly distributed, the respiratory epithelium presents scattered intraepithelial PAS-positive glands which are concentrated in the anterior portion and close to the nasopharyngeal duct. In the olfactory region prevail Bowman's PAS-positive glands which are also present in the mucosa of Masera's organ, but are not seen in the olfactory mucosa of Jacobson's organ. In the latter, PAS-positive glands are found in the respiratory mucosa. Globular leukocytes, cells of connective tissue origin, are constantly infiltrating the superior regions of the respiratory and olfactory epithelia, being more numerous in female rats.     

Morphological characterisation of the digestive tract of the catfish Lophiosilurus alexandri Steindachner, 1876 (Siluriformes,Pseudopimelodidae)

The anatomical arrangement of the digestive tract and the length (cm) of the oesophagus and intestine of the catfish Lophiosilurus alexandri were described, and the intestinal coefficient was determined. L. alexandri oesophagus is short, in median position, and presents longitudinally folded mucosa, whilst its epithelium is stratified and non-keratinised, with mucous, claviform and epithelial cells. Stomach has “C” shape, with folded mucosa along cardiac region, disordered in the fundic region, and directed to the sphincter in the pyloric region. Its epithelium is simple prismatic, and cardiac and fundic portions have gastric glands. Cranial intestine is formed by pyloric flexure and descending loop attached to the right side of stomach. Middle intestine is winding and positioned to the right of caudal portion of stomach. Caudal intestine is linear and with a median position up to the anus. Intestinal coefficient was 1.39 ± 0.30 cm. Epithelium is simple prismatic with brush border and contains epithelial and goblet cells. Caudal region has highest concentration of goblet cells. Were detected neutral glycoproteins, carboxylated and sulphated acid glycoconjugates for mucous cells and goblet cells, and neutral glycoproteins for the apical region of gastric epithelial cells. Morphological features could be related to piscivorous species feeding habit.     

Mucosubstance histochemistry of Brunner's glands, pyloric glands and duodenal goblet cells in the ferret

The mucosubstance of Brunner's glands, pyloric glands and duodenal goblet cells were studied using the various histochemical methods. The secretions of both Brunner's and pyloric glands were similar in their histochemical reactions. They contained neutral mucosubstances as in these glands in man. The duodenal goblet cells showed variations in their histochemical characters. (i) The secretions of most of the deep cells and the majority of superficial cells contained sialidase-labile and sialidase-resistant sialomucins. (ii) There were a few superficial and occasional deep cells, the secretions of which contained sulphated mucosubstances. (iii) There were some goblet cells, more in the villi than in the crypts, the secretions of which contained a mixture of sialomucins and a sulphated mucin. The sialomucin was mostly sialidase-labile and partly sialidase-resistant.     

Mucosubstance histochemistry of Brunner's glands,pyloric glands and duodenal goblet cells in the ferret

Summary The mucosubstance of Brunner's glands, pyloric glands and duodenal goblet cells were studied using the various histochemical methods.The secretions of both Brunner's and pyloric glands were similar in their histochemical reactions. They contained neutral mucosubstances as in these glands in man.The duodenal goblet cells showed variations in their histochemical characters. (i) The secretions of most of the deep cells and the majority of superficial cells contained sialidase-labile and sialidase-resistant sialomucins. (ii) There were a few superficial and occasional deep cells, the secretions of which contained sulphated mucosubstances. (iii) There were some goblet cells, more in the villi than in the crypts, the secretions of which contained a mixture of sialomycins and a sulphated mucin. The sialomucin was mostly sialidase-labile and partly sialidase-resistant.     

Histochemical study of glycoconjugates in the nasal mucosa of the rat and guinea pig

Summary A histochemical study was carried out on the glycoconjugates of the nasal mucosa of rat and guinea pig using conventional techniques and peroxidase-labelled lectins. Both the respiratory mucosa and neuroepithelium were studied. Sulphate and sialic acid groups were found in the mucous layer of the neuroepithelia, Bowman's glands and goblet cells. In contrast, the nasal glands did not possess these groups, and only a few showed neutral mucins. Carbohydrate residues were more numerous in the acini of the Jacobson glands. Thus, the nasal glands in the rat and guinea pig are probably of a serous type because of the scarcity of carbohydrate residues.     

Duodenal microanatomy of the domestic cat (Felis catus)

Duodenal samples were taken from similar locations in six cats, processed, stained, and examined via light microscope. There were no prominent circular folds (plicae circulares) or stratum compactum (lamina subglandularis). The 1072 microns x 201 microns villi were covered by 46 microns high columnar epitheliocytes proximally which decreased in height (41 microns) distally and displayed a 1.1-1.7 microns striated border. Globular leukocytes, mononuclear cells, and twenty-eight goblet cells (exocrinocytus calciformis) per villus were seen. The intestinal gland (crypt of Lieberkuhn) epithelium was 20 microns tall and had a less distinct striated border. The 515 microns simple straight tubular intestinal gland layer displayed distal branching. Many mitotic figures, 12 goblet cells per gland, and occasional columnar to triangular cells with red cytoplasmic granules were seen. The thickness of the lamina propria mucosa (glandular portion) decreased from proximal to distal (563-465 microns). The lamina muscularis mucosa had two layers and decreased in thickness distally (71-28 microns). The proximal muscularis mucosa was penetrated by the ducts of submucosal (Brunner's, duodenal) glands. The tela submucosa decreased in thickness distally (593-192 microns) and contained submucosal glands with 11.5-75 microns lumina for the first 1.5-2.5 cm. However, submucosal glands could be found to a distance of 8 cm. The glandular epithelium ranged from 7.5-22.5 microns in height. Only one type of secretory cell was observed, with both mucous and serous properties. The tunica muscularis ranged from 190-1425 microns (median thickness of 557 microns) and had two layers.     

Ontogeny of the digestive tract during larval development of yellowtail flounder: a light microscopic and mucous histochemical study

The histological development and mucous histochemistry of the alimentary tract in larval yellowtail flounder were studied using light microscopy. Samples were taken when the larvae were first offered food at 3 days post-hatch, then at 7, 10, 29, 36, and 46 days post-hatch, at which time they were metamorphosing. Regional partitioning of the digestive tract into the buccal cavity, pharynx, oesophagus, post-oesophageal swelling (PES), intestine, and rectum was complete by day 10. Goblet cells were present only in the buccal cavity, pharynx and intestine by day 7, but increased in number and distribution as development continued. By day 29, the posterior zone of the oesophagus had a marked increase in goblet cell density and mucosal folding. At the transition from oesophagus to PES/stomach stratified epithelium with goblet cells changed abruptly to a columnar epithelium with no goblet cells. Multicellular glands in the PES of 36-day larvae allowed it to be defined as a stomach. The distinct brush border of columnar epithelium and the presence of goblet cells characterize the intestine and rectum. All goblet cells throughout the digestive tract were strongly positive for acid mucins as was the luminal layer of the stratified epithelia lining the buccal cavity, pharynx and oesophagus. The PES/stomach epithelium stained weakly for neutral mucins. No mucin staining was associated with the gastric glandular epithelium. The brush borders of the intestine and rectum were strongly positive for combinations of neutral and acid mucins.     

Anatomical features and histology of the digestive tract of two related neotropical omnivorous fishes (Characiformes; Anostomidae)

The estimated mean intestinal coefficients of Leporinus friderici Bloch, 1794 and L. taeniofasciatus Britski, 1997, from the Upper Tocantins River, central-western Brazil, were 1·25±0·15 and 1·14±0·07, respectively. The external surfaces of the lips have taste buds. The histological structure is composed of four layers: mucosa, submucosa, muscular, and serosa. No muscularis mucosa is detected. The oesophageal epithelium is stratified in L. friderici and pseudostratified in L. taeniofasciatus , the latter with PAS+ basal cells and eosinophilic apical cells. A thick layer of adipose tissue was found within the submucosa. Leporinus taeniofasciatus has a sphincter separating the cardiac and fundic portions of the stomach. In both species, gastric glands are present in the stomach, except in its pyloric portion. The pyloric caeca possess a simple columnar epithelium with brush border and three types of goblet cells. Rodlet cells were found in L. friderici . The three portions of the intestine showed no histological differences. Anatomical and histological features of the digestive tract are consistent with the omnivorous habit of both these species.     

The respiratory system of the genusCallithrix,the South American monkey

It has been described the cytology of the following parts of the respiratory system of some South American primates:Callithrix jacchus andCallithrix argentata melanura. The nasal cavities are divided into three parts: a vestibule, covered with a stratified nonkeratinized squamous epithelium; the respiratory portion, consisting of a pseudostratified columnar ciliated epithelium with goblet cells and the olfactory portion which is also covered with a high respiratory epithelium without goblet cells. The trachea is lined with a mucous membrane, whose epithelium is pseudostratified columnar ciliated with scarce goblet cells in the proximal portion unlike to the distal one. In the dorsal portion of the trachea, at the level of the gap between the two ends of incomplete cartilaginous rings, the epithelial lining is of transitional type. The incomplete hyaline cartilaginous rings present centers of calcification. The right and left lungs consist of two and three lobes respectively characteristic for these species, but they are not divided into lobules by connective tissue as in other ones. The bronchi, bronchioles and the respiratory portion, respiratory bronchioles, alveolar ducts, alveolar sacs, and alveoli present the typical respiratory structure with exception of their cartilaginous configuration; the cartilage continues as far as the respiratory bronchioles and alveolar ducts. These last structures are formed by a thin squamous epithelium, in which we observed two types of alveolar lining cells. This work was supported by grants from the Consejo Nacional de Investigaciones Cientificas y Técnicas (CONICET) and EHIGE program. Postgraduated fellow from CONICET. established Investigator and Director of EHIGE (Estudio Histológico comparado del Sistema de Glándulas Endócrinas) from CONICET.     

Some morphological and histochemical studies on the intestinal tract of the Brazilian sloth (Bradypus tridactylus)

The intestinal of the 3-toed sloth, Bradypus tridactylus, was studied macroscopically, with light microscope and with histochemical methods for mucosubstances. Macroscopically, the inner surface of the duodenum shows longitudinal and circular folds. There is no caecum, nor appendix. The large intestine consists of a short colon and a large rectal pouch, which has a thick wall. The mucosa of the small intestine has long leaf-shaped villi covered with columnar epithelium having a well developed striated border, and the goblet cells are scattered among the columnar cells. An association between neutral and acidic mucosubstances was detected in the goblet cells. The duodenal (Brunner's) glands are confined exclusively in the lamina propria of the duodenum. No Paneth cells were observed in the crypt lining. Argyrophil and argentaffin cells were found in the entire length of the intestine. The large intestine does not possess villi, but many goblet cells were observed in its mucosa.     

Segmentation of microscopic images of small intestinal glands with directional 2-D filters

We present an image segmentation algorithm for small intestinal glands consisting of goblet cells that are evenly distributed and arranged in parallel at the base. Making use of the properties of the chain distribution of the goblet cells, directional 2-dimensional (2-D) linear filters with different orientations were designed to enhance the rims of the intestinal glands. Segmentations are based on the combined responses of the multiple zero-phase directional 2-D linear filters. For comparisons, outputs of combined directional filters are shown along with those of the comparable nondirectional Gaussian filters. Segmentation results of small intestinal glands of both normal and cancer cases are provided.     

Morphological assessment of the activity of mucus-producing structures of the rat duodenum after administration of varying-dispersion wheat germ rations

Three groups of Wistar rats were fed a wheat-bran diet of different size particles for each group during three months. Goblet cells and duodenal glands are sated to develop a more intensive mucous secretion in case of coarse bran particles. Mucous composition and the length of the area of the duodenal glands are not influenced by the size of the diet particles. The idea of the goblet cell renewal rate and the diet particle size correlation is suggested.     

Cytochemical features of the digestive tract mucosa of Hemisorubim platyrhynchos (Siluriformes: Pimelodidae)

Membranous organelles, acid glycoconjugates and lipids were characterized in the digestive tract mucosa of Hemisorubim platyrhynchos by cytochemistry techniques. Two types of mucous‐secreting cells were observed in the digestive tract epithelium: goblet cells in the oesophagus and intestine and epithelial cells in the stomach. These cells had a Golgi apparatus more developed than the other cell types. The cytochemical analysis revealed that secretory granules are reactive to acid glycoconjugates, varying in reaction intensity according to the region of the digestive tract. Acid glycoconjugate reactions were also observed in oesophageal epithelial cell microridges and in enterocyte microvilli. In the digestive tract, acid glycoconjugates act to protect the epithelial surface, increasing mucous viscosity, which facilitates the passage of food, prevents the binding of parasites and facilitates their removal. Through lipid staining, a coated membrane was observed around each secretory granule of the oesophageal and intestinal goblet cells, while gastric epithelial cells granules were fully reactive. Oxynticopeptic cells of the gastric glands showed lipid droplets in the cytoplasm and also in the mitochondrial matrix, which act as an energy reserve for these cells that have a high energy demand. Enterocytes showed a well‐developed smooth endoplasmic reticulum, especially in the apical region of the cell, being related to absorption and resynthesis of lipids.     

Use of an antiserum against deglycosylated human mucins for cellular localization of their peptide precursors: antigenic similarities between bronchial and intestinal mucins

Highly glycosylated regions of mucins, or glycopeptides, were obtained by proteolysis of human bronchial mucins. They were deglycosylated by treatment with a trifluoromethane sulfonic acid/anisole mixture and subsequent solvolysis with anhydrous liquid hydrogen fluoride. The resulting peptides were then used to raise an immune serum in rabbit. This immune serum was used to localize the peptide precursors of human respiratory mucins within bronchial cells, using an immunohistochemical method. Two main patterns of labeling were observed in the goblet cells: the entire cytoplasm of some goblet cells was immunoreactive, whereas in other cells the labeling was concentrated around the nucleus. In the respiratory mucous glands, the labeling was localized around or below the nucleus. The serous cells were not stained. Similar labeling was observed in human colon goblet cells. This immune serum seems to be specific for mucin-secreting cells and has a strong affinity for the perinuclear region of these cells.