Oxynticopeptic Cells Research Articles

Structural-functional changes in the proventriculus of poultry infected with transmissive viral proventriculitis

Transmissive viral proventriculitis (TVP) is a new avian disease, the etiology and pathogenesis and diagnostics of which remain unidentified, being therefore a subject of an active ongoing discussion among researchers and veterinary doctors. Cases of the disease have been reported and registered in many countries of the world. On poultry farms of Ukraine, this disease started to be diagnosed in 2019, according to the characteristic pathognomic changes. The article presents the results of pathoanatomical, histological and electronic-microscopical studies of the glandular part of the stomach of 62 ill broiler chickens aged 24-28 days and 7 clinical healthy broiler chickens of the same age. The samples of the proventriculus from the infected and clinically healthy chickens were fixated in 10% aqueous solution of neutral formalin and in 1.5% solution of glutaraldehyde in 0.2 molar cacodylate buffer (рН 7.2). Pathoanatomic necropsy of the infected broiler chickens revealed overall anemia, decrease in the volume of the spleen, thymus and fecal sac. In the glandular part of the stomach, the wall was slightly thickened, non-homogenously stained on the section, the mucous membrane being swollen, covered by dense whitish mucous. According to the histological study, the proventriculus of the broiler chickens had lymphocytic necrotizing proventriculitis. In the tubular-alveolar structures of the mucous membrane, there prevailed alteration of the secretory epithelium, with its transformation into ductal epithelium, combined with lymphocytic infiltration of the interstitium. Intensive necrosis of most glandular (oxynticopeptic) cells was accompanied by their exfoliation from the basal membrane of the secretory parts, with desquamated cells accumulating in enlarged lumens of alveoli and excretory ducts. Further, necrotized oxynticopeptic cells in the tubular-alveolar glands were actively replaced by cylindrical ductal cells, and also their hyperplasia and hypertrophy occurred. Diffusive and multifocal interalveolar round-cell infiltrates were mostly presented by lymphocytes, among which there occurred plasmocytes, macrophages, and heterophils. Ultrastructural studies of secretory cells revealed presence of pathogen virions in nucleus and cytoplasm. Based on the morphological changes in the birds’ proventriculus, we diagnosed transmissive viral proventriculitis, which had not been recorded in Ukraine before.

Histomorphology and ultrastructure of the proventriculus of the broad breasted white turkey (Meleagris gallopavo, Linnaeus 1758).

This study aims to examine the functional morphology of the proventriculus of the broad breasted white turkey (BBWT) (Meleagris gallopavo, Linnaeus 1758) using gross anatomy, light microscopy, gross/histomorphometric analysis, and scanning and transmission electron microscopy. The proventriculus was characterized internally by many elevated papillae with a mound, leafy flower, and lotus flower-shapes. Each papilla was enclosed by concentrically organized mucosal folds with distinct or indistinct proventricular gland openings on its top. Longitudinal folds and grooves at the junction of the proventriculus with the esophagus exhibited various sized and shaped openings of esophageal glands with irregular outlines. Histologically, the surface epithelium of the proventriculus was covered by a thin layer of cuticle, particularly evident at its junction with the gizzard. The lamina epithelialis and propria, and secretory units of proventricular lobules were infiltrated by aggregations of lymphocytes and lymphoid follicles (nodules). Variably shaped glandular lobules of proventricular glands occupied the submucosa, surrounded by thin strands of smooth muscle fibers derived from muscularis mucosa. Triangular, cuboidal, or columnar-shaped secretory oxyntico-peptic cells lined the secretory units. Many telocytes (pyramidal or fusiform-shaped cell bodies with lengthy telopodes) were observed in interstitial tissue. Further, two types of argyrophilic endocrine cells were identified within the glandular epithelium. The morphology of the M. gallopavo proventriculus reflects its dietary habits and behavior.

Histomorphological, histochemical and scanning electron microscopic investigation of the proventriculus (Ventriculus glandularis) of the hooded crow (Corvus cornix).

The current investigation aimed to clarify the histomorphological features, scanning electron microscopy (SEM) and histochemistry of the proventriculus in the adult hooded crow (Corvus cornix). Twenty-two adult birds of both sexes were collected from El-Fayoum and Beni-Suef governorates, Egypt; ten were used for anatomical investigation, two were scanned using SEM, and ten were subjected to routine histological technique. The obtained anatomical results revealed a small-sized spindle-shaped proventriculus obliquely located in the left ventral part of the body cavity with an average body weight, length and diameter of 1.689±0.231gm, 1.54±0.383cm and 3.51±0.416cm, respectively. The histological examination revealed a typical tubular organ. The mucosa exhibited several plicae and sulci that were lined with simple columnar cells. The lamina propria was composed of collagenous connective tissue infiltrated by lymphocytes, lymphatic aggregations and tubular glands. The submucosa consisted of collagenic fibres and compound tubuloalveolar glandular lobules lined with oxynticopeptic cells and enteroendocrine cells. The oxynticopeptic cells reacted negatively with PAS and Alcian Blue stains, whereas the ductal cells reacted positively with PAS only. Enteroendocrine cells were seen singly in the lamina epithelialis mucosae and were abundant in submucosal glands. The tunica musclaris was arranged in two layers covered by serosa. The proventricular glands' openings were noticed by SEM as raised tubes with regular circular outlines surrounded by anastomosed microscopic folds. The obtained histomorphological structure of the hooded crow's proventriculus revealed some shared morphological features with most species of birds and some variations that might be attributed to their diet and feeding behaviour.

Micromorphological study of the upper digestive tract of the Argentine tegu (Salvator merianae).

Argentine black and white tegus (Salvator merianae) are omnivorous lizards native to southeastern Brazil, Uruguay, eastern Paraguay and northern Argentina, and are invasive species in Florida and Georgia, USA. They are opportunistic feeders, which is what allow them to have such a diverse variety of foods. Tegus raised a particular concern due to their adaptive capability to different environments. Our goal was to provide a micromorphology baseline of oesophagus and stomach and correlate findings with their dietary and invasive capabilities. Four Argentine black and white tegus were used for this study. We collected and processed specimens from oesophagus and stomach using standard histological techniques and stained tissue sections using Haematoxylin and Eosin (H&E), Periodic Acid Schiff (PAS), Alcian Blue (AB) and Verhoef's elastic stains. The oesophagus was lined with ciliated pseudostratified columnar epithelium (PSCE) with goblet cells. Gut-associated lymphoid tissues (GALT) were present occasionally in the oesophagus and more frequently in the stomach. Tunica muscularis (Tm) of the oesophageal-gastric junction had distinct smooth muscle which could function as a sphincter. The mucosa of the stomach was lined with simple columnar epithelium (SC). The glands had neck and dark oxyntico-peptic cells. The pyloric sphincter had more GALT and mucus cells than other regions. The Tm outer layer is thinner than the inner. Presence of large number of goblet cells would support faster transit of the bolus. The short digestive tract and the histological features observed are consistent with the ability of tegus consumption of large amount of food.

Ultrastructure and Morphometric Analysis of Interstitial Cells of Cajal in the Gastric Wall of the Bullfrog (Rana catesbeiana)

Interstitial cells of Cajal (ICC) play a vital role in the gastrointestinal motility. However, information on ICC in lower vertebrates is rare. Here, ICC and ICC-like features of the gastric wall in the bullfrog (Rana catesbeiana) were observed by light microscopy and transmission electron microscopy. The lengths and distances of the ICC/ICC-like features were measured by morphometric analysis. The gastric wall contained mucosa, submucosa, tunica muscularis, and serosa. The gastric glands contained mucous cells and oxynticopeptic cells. The ICC with 1–3 processes were located among smooth muscle cells (SMC) of the tunica muscularis. Moreover, the ICC-like features were observed among oxynticopeptic cells of the mucosa. The processes of ICC established direct contacts with SMC. Also, the gap junctions were observed between the processes of ICC and nerve fiber bundles in the tunica muscularis. The multivesicular bodies, including shedding exosomes, were frequently observed between ICC and SMC. In addition, ICC-like features and their processes were observed in close proximity to oxynticopeptic cells and blood vessels. Our findings illustrated that ICC are present in the gastric tunica muscularis, and ICC-like features were in the mucosal lamina propria of the gastric wall of R. catesbeiana. These histological evidences supported the notion that ICC are implicated in gastric motility.

Histology and ultrastructure of the gastrointestinal tract in four temperate marine herbivorous fishes.

While alimentary tract anatomy in many terrestrial herbivorous vertebrates is well documented, the digestive systems of marine herbivorous fishes are poorly characterised. The gastrointestinal tract (GIT) of four species of marine herbivorous fishes from northeastern New Zealand, butterfish Odax pullus (Labridae), marblefish Aplodactylus arctidens (Aplodactylidae), notch-head marblefish A. etheridgii (Aplodactylidae) and silver drummer Kyphosus sydneyanus (Kyphosidae), were examined using histology and transmission electron microscopy (TEM) to provide a detailed histological and ultrastructural description of gut anatomy. Gastric glands were distributed over rugae in the stomach of A. arctidens, A. etheridgii and K. sydneyanus. The luminal surface of the stomach of these three species was lined by columnar mucous cells, and oxynticopeptic cells lined the glands in the stomach. Villi were present along the length of the intestine in all four species. The anterior intestine had thin musculature, and was lined by absorptive cells with long microvilli and numerous small vesicles in the apical cytoplasm. The posterior intestine was lined by absorptive columnar cells with long microvilli, invaginations between microvilli with electron-dense membranes, and pinocytotic vesicles. Surface area generally decreased from the anterior to posterior intestine. Histological and ultrastructural results were consistent with lipid absorption occurring in the anterior GIT and protein absorption in the posterior GIT. The results of this study indicate clear differences in GIT structure among the study species, and digestion models based on chemical reactor theory were developed to characterise these differences.

Histological and histochemical studies of the gastrointestinal tract in the water monitor lizard (Varanus salvator)

AbstractThe histological and histochemical studies of gastrointestinal tract (GI tract) are important for understanding the morphophysiology in animal digestive processes. Therefore, this study aimed to describe and analyse the histological and histochemical characteristics of Varanus salvator GI tract based on two adult wild‐caught specimens (male and female). The results of histological study revealed that most of V. salvator GI tract is quite similar to that of other vertebrates. However, only slight differences were found in some histological aspects. According to the fine structure of stomach, the oxynticopeptic cells of oral fundic region contained numerous secretory granules, while those of the aboral fundic region contained less secretory granules. For the mucin histochemical study, the acid and neutral mucins can be found throughout the GI tract except for pyloric stomach found neutral mucin only. This study provides information about the microanatomic structures of V. salvator GI tract that could be applied to the biological and veterinary sciences, and farming and feeding management.

Morphological and histochemical features of the digestive tract of Leiarius marmoratus (Gill, 1870).

Leiarius marmoratus, a freshwater catfish from Pimelodidae family, shows great biological and commercial relevance because of its geographic distribution and adaptation to fish-farm. The knowledge of the morphological characteristics of the digestive tract is fundamental to the understanding of fish physiology and nutrition, which helps in the planning of diets to provide better management and success in fish farming. Thus, this work described the morphology and histochemistry of the digestive tract of L. marmoratus adults. After euthanasia, the animals were dissected for analysis of the digestive tract. The oesophagus is a short and distensive organ with longitudinal folds that allow the passage of large food, e.g., other fishes. Oesophageal mucosa layer shows a stratified epithelium with goblet cells and club cells. The secretion of goblet cells is composed of neutral and acidic mucins that are anchored in the epithelium luminal face by epithelial cells fingerprint-like microridges, lubricating the surface to facilitate the food sliding. Club cells have protein secretion that can be involved in alarm signals when epithelium is damaged and in immunological defence. The saccular stomach is highly distensible to store large food. Gastric mucosa layer is composed of epithelial cells with intense secretion of neutral mucin to protect against self-digestion of gastric juice. Cardiac and fundic regions of stomach show well-developed gastric glands composed of oxynticopeptic cells. These cells have numerous mitochondria, highlighting their intense activity in the synthesis of acid and enzymes. The intestine is divided into three regions: anterior, middle and posterior. Although it is a short tube, intestine shows longitudinal folds and microvilli of enterocytes to increase the contact surface. These folds are higher in the anterior region of the intestine, highlighting their function in digestion and absorption. Intestinal goblet cells have acidic and neutral mucins that lubricate the epithelium and aid in digestive processes. These cells increase in number towards aboral, and they are related to the protection and lubrication to expulsion of faecal bolus.

Gastrointestinal Tract and Accessory Organs in the Spotted Bent-toed Gecko, Cyrtodactylus peguensis (Boulenger, 1893): A Histological and Histochemical Study

AbstractThe spotted bent-toed gecko Cyrtodactylus peguensis is one of the exploited reptiles in Thailand. In order to provide basic information for the digestive system of this species, we have examined histologically the gastrointestinal and accessory organs of C. peguensis using routine methods. The gastrointestinal region of this reptile started from the stomach and the intestine. The stomach was separated into fundic and pyloric regions. In both regions, the stomach wall was formed by four distinct tissue layers, including mucosa, submucosa, muscularis, and serosa layers. Mucous neck cells and oxynticopeptic cells were identified as glycoprotein-producing cells in the stomach by Periodic acid-Schiff (PAS) staining. The small and large intestines shared many histological characteristics, but the former contained more intestinal folds, while the latter had more PAS-positive goblet cells. Histological characteristics of accessory organs, liver and pancreas, were also provided. Overall, the gastrointestinal and accessory organs of C. peguensis were largely similar to those from other reptiles, but fine structural information will open up considerable opportunities to further studies related to the endocrinology, the physiology, and the conservation of this species.

HISTOCHEMICAL ANALYSIS OF STOMACH OF GRASSCUTTER (Thryonomys swinderianus)

The Grasscutter (Thryonomys swinderianus), is a wild herbivorous rodent peculiar to Africa. It is widely eaten in Nigerian rural communities as a protein source hence its domestication as microlivestock. There is paucity of data on the histochemical studies. This study was aimed at histochemically analyzing the stomach in order to determine if it exhibits regional differences in its qualitative expression of acid, neutral and carboxylated mucin. Seven animals obtained from the wild and domesticated in the animal house of the Department of Human Anatomy, Ahmadu Bello University, Zaria were used. Histologically, stomach of the Grasscutter was simple, glandular and composed of three regions: cardia, fundic‐body and pyloric. Cardia region showed enlongated tubular glands, coiled at the lower end with an opening continuous with the long conspicuous gastric pits. Fundic‐body region showed numerous gastric glands which open into fewer shorter gastric pits while the pyloric region showed simple tubular glands which are highly branched as such obscures the depth of the gastric pits. Histochemically, stomach of the Grasscutter exhibits regional polymorphism in the mucin content with the glands showing weak alcianophilic reactions. Cardia and pyloric regions demonstrated neutral periodic acid Schiff (PAS) reaction characterized by purple coloration thus indicating the presence of neutral mucins. Fundic‐body region exhibited strong PAS positive reaction particularly at the apical cytoplasm of the oxynticopeptic cells indicating the presence of carboxylated mucins. Results demonstrate that regional differences in the expression of mucins occur in the stomach of African Grasscutters, thus this may provide basic information for further nutritional and conservative studies.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Structure of the alimentary tract in the Atlantic mudskipper Periophthalmus barbarus (Gobiidae: Oxudercinae): anatomical, histological and ultrastructural studies

The alimentary tract of oxudercine gobies is characterized by a lack of an anatomically distinct stomach, owing to which they are classified as stomachless. Since the environment, food requirements, and feeding habits have a significant impact on the anatomy of the alimentary tract of fish, it was assumed that predominantly carnivorous, semi-terrestrial mudskippers would have a stomach. In order to verify this hypothesis, anatomical, histological, histochemical and ultrastructural analysis of the alimentary tract of the Atlantic mudskipper Periophthalmus barbarus was performed. The results revealed that despite a lack of clear anatomical distinction within the alimentary tract, there were four well-distinguished sections visible at the histological level: oesophagus, stomach, intestine, and rectum. The division was enhanced by the presence of a pyloric sphincter and an ileorectal valve. The stomach contained tubular glands composed of oxynticopeptic cells. Gland cells had pepsinogen granules and a well-developed tubulovesicular network of smooth membranes, which indicates the secretion of gastric juice. The presence of neutral mucus in the apical region of surface epithelial cells as protection against hydrochloric acid as well as the presence of active pepsin also confirm gastric function. However, low pepsin activity seems to implies low protein digestion. The results of this study indicate that the Atlantic mudskipper P. barbarus has a functional stomach.

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.

Esophagogastric region and liver tissue in dog-faced water snake Cerberus rynchops: Histology and histochemistry

Observation of the esophagogastric region and liver tissue of the dog-faced water snake, Cerberus rynchops, living in Thailand was evaluated using standard histological techniques. The results revealed that the digestive tract of this snake consists of three parts: the oesophagus, stomach and intestine, respectively. From the histological analysis, the longitudinal folds of the oesophagus were lined by pseudostratified columnar epithelia with goblet cells. The goblet cells stained positively with periodic acid-Schiff (PAS) and alcian blue (AB) methods. In the stomach, gastric glands extended into the lamina propria. Each gastric gland had a greater cell size than other regions and also a branched tubular gland was visible in the histological images. The mucous neck cell was positive to PAS and AB reactions, whereas, the oxynticopeptic cells slightly reacted to both PAS and AB staining and were preferentially located in this gland. The liver parenchyma of C. rynchops was composed of hepatic sinusoids and hepatocytes. In conclusion, this was the first study on digestive tract and liver tissue in C. rynchops from the Paknam Pranburi Estuary, Thailand.

Developmental morphology study on the stomach of African ostrich chicks

This study investigates the developmental morphology changes on the proventriculus and gizzard of African ostrich chicks using gross anatomy, and light and transmission electronic microscopy. The body weight; the weight of the proventriculus and gizzard; the thickness of simple tubular glands, muscularis mucosae, compound tubular glands, and muscular layer of the proventriculus; and the thickness of the gizzard glands and muscularis mucosae were measured on postnatal d one, 45, 90, and 334. Under transmission electronic microscopy, the oxynticopeptic cells, mucous cells, and endocrine cells were observed in the proventriculus on postnatal d one, 45, and 90. Our results revealed that the weights of the proventriculus and gizzard (relative to the body weight) both peaked on d 90, respectively, and declined thereafter. The thicknesses of the simple tubular glands, muscularis mucosae, compound tubular glands, muscular layer of the proventriculus, and gizzard glands increased with increasing bird age. However, the thickness of the muscularis mucosae in the gizzard peaked on d 90 and gradually decreased thereafter. The result of transmission electron microscopy revealed that the glands in the submucosa layer of the proventriculus did not differ from other cell types, aside from an increase in cell diameter and an increase in cytoplasmic content. A significant increase in the number of mitochondria and smooth endoplasmic reticulum was noted, as well as an in granules secreted by endocrine cells. Therefore, to improve brood rates of reared African ostrich chicks, feed management ought to be enhanced between postnatal d one and day 90.

Morphology of the proventriculus of African ostrich

The objective of this study was to investigate the morphological features of the proventriculus of African ostrich (Struthio camelus). The location, appearance, and histological characteristics of the proventriculus were observed on postnatal day 90. The entire proventriculus had the appearance of a distensible sac; and exhibited a large number of glands. Under light microscope, the proventriculus wall was composed of mucosa, submucosa, muscular layer and adventitia. The mucosa was further divided into the lamina epithelialis, lamina propria, and muscularis mucosae. The submucosa was relatively thick and contained compound tubular glands having oxynticopeptic cells, mucous cells, and endocrine cells. These features of the proventriculus are possibly related to the dietary habits of the African ostrich, and they imply that this specie has a strong ability to digest and absorb food.

Histomorphological, histochemical, and ultrastructural studies on the stomach of the adult African catfish (Clarias gariepinus)

This study investigated the morphology, histochemistry, and ultrastructure of the adult African catfish (Clarias gariepinus) stomach in order to detect the functional aspects involved in gross and histological studies to get detailed information about the precise cellular structures of different cells lining the stomach. Forty fishes were used in this study. The stomach is a J-shaped sac divided into three regions: (1) cardiac; (2) fundic; and (3) pyloric. Histologically, its wall is composed of four tunics: (1) mucosa; (2) submucosa; (3) muscularis externa; and (4) serosa. The mucosa of the three portions showed thick longitudinal folds lined with simple high columnar cells containing oval basally located nuclei. These cells contained apically located mucosubstances that reacted positively with Periodic–acid Schiff and negatively with Alcian blue stains. Many gastric pits were formed by invaginations of the mucosal layer into the underlying lamina propria and continuous with the openings of the gastric glands. Only the cardiac and fundic regions contained mucosal glands. The fundic glands were lined with oxynticopeptic cells. Enteroendocrine cells were distributed in the gastric wall within the epithelial cells of the gastric mucosa and gland. The lamina propria composed of extensive collagen fibers, many blood vessels, and nerves. Strands of smooth muscle fibers situated between the lamina propria and the submucosa forming lamina muscularis mucosa. Loose connective tissue was the main component of the tunica submucosa. The pyloric portion had the thickest musclosa and the serosal coat of the stomach was formed of loose connective tissue containing blood vessels.

Microanatomy of the digestive system of Supachai's caecilian,Ichthyophis supachaiiTaylor, 1960 (Amphibia: Gymnophiona)

AbstractThe gross anatomy and microanatomy of the digestive system ofIchthyophis supachaiiwere investigated. The microscopic structures of the digestive system are similar to those in other caecilians. Functional and developing teeth are present in adults. The tongue contains the genioglossus muscle. The digestive tract is elongated and consists of the mucosa, submucosa, muscularis and adventitia/serosa. The oesophagus contains longitudinal folds and lacks oesophageal glands. We report for the first time the caecilian gastric rugae and specific localization of oxynticopeptic cells in the anterior gastric region. The intestinal folds are exclusively present in the anterior intestinal region. The liver comprises 30–40 incomplete hepatic lobes, lying in an imbricate manner. Each lobe is enveloped by haematopoietic tissue that produces and delivers blood cells into sinusoids. Hepatic parenchyma is organized into anastomosing, two‐cell‐thick plates, having sinusoids at the basal domain and bile canaliculi at the apical domain of hepatocytes. Pigment cells are scattered inside sinusoids. The pancreas contains pancreatic acini interspersed with islets of Langerhans. The gallbladder proper is thin and continuous with the cystic duct wall. Neutral and carboxylated acid mucosubstances are secreted along the digestive tract, while sulphated mucosubstances are not produced by the stomach and anterior intestinal regions.

Acid and alkaline phosphatase localization in the digestive tract mucosa of the Hemisorubim platyrhynchos

This cytochemical study investigated the acid and alkaline phosphatase of the digestive tract of Hemisorubim platyrhynchos. Acid phosphatase was detected in the lining epithelium throughout the digestive tract, whereas alkaline phosphatase was only observed in the intestine. In the esophagus, an acid phosphatase reaction occurred in the apical cytoplasm of the epithelial cells and was related to epithelial protection and freeing of superficial cells for sloughing. Similar results were also observed in epithelial cells of gastric epithelium. In the gastric glands, acid phosphatase occurred in lysosomes of the oxynticopeptic cells acting in the macromolecule degradation for use as an energy source, whereas in the vesiculotubular system, its presence could be related to secretion processes. Furthermore, acid phosphatase in the intestine occurred in microvilli and lysosomes of the enterocytes and was correlated to absorption and intracellular digestion. However, no difference was reported among the regions of the intestine. However, alkaline phosphatase reaction revealed a large number of reaction dots in the anterior intestine, with the number decreasing toward the posterior intestine. This enzyme has been related to several functions, highlighting its role in the nutrient absorption primarily in the anterior intestine but also being essential in pH regulation because this is a carnivorous species with many gastric glands with secretions that could damage the intestine.

Histogenesis of the stomach of the pre-hatching quail: a light microscopic study.

The current study conducted a careful description of the histological events during the embryonic development of quail stomach. Daily histological specimens from the quail stomach from day4 to day 17 post incubation were examined by light microscopy. The primitive gut tube of the embryonic quail appeared at day4 post incubation. The gut tube consisted of an endodermal epithelium of pseudostratified type, surrounded by splanchnic mesenchyme. The prospective glandular epithelium invaginated at day 5 in the proventriculus and gradually developed to prospective proventricular glands. The muscular coat became distinguished at day 7 and day 8 in the proventriculus and gizzard, respectively. Transformation into simple columnar epithelium occurred in both proventriculus and the gizzard at day 12. The gizzard epithelium gave rise to tubular invaginations also at day 12. Canalization of the gizzard tubular glands was recognized at day 14. By day 15, the proventricular surface epithelium invaginated in a concentric manner around a central cavity to form immature secretory units that contained inactive oxyntico-peptic cells. The mucosal folding in the gizzard appeared at day 15 to form plicae and sulci. The wall of the proventriculus and gizzard at day 17 acquired histological features of post-hatching birds.

Ontogeny of digestive organs during early developmental stages of the tropical whitespotted bamboo shark, Chiloscyllium plagiosum – a histological study

This study was undertaken to address a lack of understanding of the early developmental stages of the tropical elasmobranch whitespotted bamboo shark, Chiloscyllium plagiosum, to assist with advancement of its aquaculture. It is the first report of the histological and ultrastructural characteristics of its developing digestive tract. The study was carried out from hatching to 60 days after hatching (DAH). Embryos for this study were maintained in the laboratory. Histological investigations yielded the following data. At hatching, the gut of an embryo consisted of an undifferentiated straight tube that lay over the yolk sac. The digestive tract was differentiated into buccopharynx, esophagus, stomach, and intestine by 8 DAH. During the preflexion phase (within 16 DAH), the mucous cells of the esophagus were differentiated. Gastric glands were present at 60 DAH, indicating the transition from the embryonic to the juvenile stage and the acquisition of an adult mode of digestion. The lumen of the intestine appeared on 6 DAH; the intestinal valve appeared and divided the intestine into anterior and posterior sections on 20 DAH. The liver and the pancreas were formed on 8 DAH. The yolk sac was partially depleted by 80 DAH. In terms of ultrastructure, on 30 DAH, the anterior section of the esophagus was lined by a stratified epithelium, whereas the posterior section was lined by simple tall columnar epithelial cells. Goblet cells and oxynticopeptic cells were found in the stomach. The pancreatic acinar cells were strongly elongated and of two types: one with a pale and the other with a more opaque cytoplasm.