Localization of NO-Ergic Structures in Oral Lobes, Labia, and Esophagus of the Bivalve Mollusc Crenomytilus grayanus

Localization of NO-ergic elements in oral lobes, labia, and esophagus in the bivalve mollusc, mussel Crenomytilus grayanus was studied using histochemical technique [1] for detection of NADPH-diaphorase (EC 1.6.99.1). The NO-producing elements were revealed in all studied parts of the digestive system. NADPH-diaphorase was found in nerve and secretory cells as well as in nerve plexuses. Numerous NO-ergic nerve cells were observed in the basal part of epithelium of labia and of the initial part of esophagus as well as in the subepithelial area of these organs. In the middle and posterior parts of esophagus, only subepithelially located NO-ergic nerve cell are present. Basiepithelial NO-producing secretory cells are found in all the parts, but most of these cells are observed in labia and the initial part of esophagus. Subepithelial secretory cells labeled with diformazan granules are spread from the folded surface of oral lobes to the initial part of esophagus; no such cells were found on the smooth surface of the lobes. The deposit labeled basi- and subepithelial nerve plexuses in all studied organs except for oral lobes. These plexuses are the most developed in labia and the initial part of esophagus of the studied mollusc.     

An autoradiographic investigation of the proliferative activity of pyloric caeca and gondas of Asterias rubens

The proliferative activity of the pyloric caeca of Asterias rubens was investigated. Autoradiographic experiments using intracoelomically injected (methyl-³H)-thymidine were performed throughout the year and incorporation into pyloric caeca and into gonads was studied. Tritiated thymidine was found to be incorporated mainly in the coelomic lining of both organs. Cell divisions in the coelomic lining may be necessary for the growth of these organs, for the production of coelomocytes or, in the case of the pyloric caeca, for growth of the digestive epithelium. Proliferative activity of the digestive epithelium of the pyloric caeca was only observed in the median duct. It is hypothesized that new cells, arising from mitosis, grow from the median duct to the side lobes and differentiate into storage cells, for example. The existence of a mitosis-inducing or mitosis-stimulating substance is discussed. In the ovaries follicle cells were found to incorporate (methyl-³H)-thymidine; in the testis, proliferation of the germinal epithelium occurred simultaneously in all spermatogenic columns. First, the spermatogonia and then later the spermatocytes became labeled. Absorption of substances from the coelomic fluid is discussed.     

An immunohistochemical study of the pancreatic endocrine cells of the nude mouse, Balb/c-nu/nu

The regional distribution and frequency of the pancreatic endocrine cells in the nude mouse, Balb/c-nu/nu were studied by immunohistochemical (peroxidase anti-peroxidase; PAP) methods using specific antisera against insulin, glucagon, somatostatin and human pancreatic polypeptide (hPP). The pancreas of the mouse was divided into two lobes, the splenic and duodenal lobes, and each lobe was subdivided into three regions, the pancreatic islets (central and peripheral regions), the exocrine region and the pancreatic duct region (consisting of duct epithelium and surrounding connective tissue--sub-epithelial connective tissue). In the pancreatic islets, most of insulin-immunoreactive (IR) cells were located in the central region, and glucagon-, somatostatin and hPP-IR cells were located in the peripheral region regardless of the lobe. In the splenic part, glucagon-IR cells were also located in the central regions, and more numerous somatostatin-IR cells were detected in the central regions compared to those of the duodenal part. hPP-IR cells were restricted to the peripheral regions in both lobes but more numerous cells were detected in the duodenal portion as compared to those of the splenic portion. In the exocrine parenchyma of the splenic lobe, only insulin-, glucagon- and somatostatin-IR cells were detected.. Here, the insulin- and glucagon-IR cells formed cell clusters, while somatostatin-IR cells were present as solitary cells. In the exocrine region of the duodenal portion, only insulin-, somatostatin- and hPP-IR cells were observed, with the same distributional pattern as that found in the splenic lobe. However, clusters of cells consisting only of hPP-IR cells were distributed in the pancreas parenchyma as small islets. In the pancreatic duct region, only solitary hPP-IR cells were demonstrated in the sub-epithelial connective tissue regions of the splenic portion. In conclusion, some strain-dependent characteristic distributional patterns of pancreatic endocrine cells, especially of the hPP-IR cells, were found in the nude mouse. In addition, somewhat different distributional patterns were found between the two pancreatic lobes.     

A Golgi study of the hypothalamus of Actinopterygii

The posterior hypothalami of the polypteriform, Calamoichthys, and of the teleost, Anguilla, were studied by means of the Golgi technique. In Calamoichthys, the lateral lobes are not developed and the median lobe is simple. In Anguilla, the median (tuberal) lobe shows lophodendritic, CSF-contacting cells and horizontal cells in the periventricular grey and some reticular elements directed toward the cell-poor lateral areas. In the lateral lobes the periventricular grey is formed by multipolar neurons and a diffuse population of multipolar cells of uncertain identity. The nucleus diffusus lobi lateralis is formed by scarce multipolar neurons, often placed next to the external surface of the brain. The organization of the lateral lobes in Actinopterygii is reminiscent of highly developed integrative regions.     

The trophotaenial placenta of a viviparous goodeid fish. I. Ultrastructure of the internal ovarian epithelium, the maternal component

Embryos of goodeid fishes develop to term within the ovarian lumen, where they undergo considerable increase in weight due to transfer of maternal nutrients across a trophotaenial placenta. The placenta consists of an embryonic component, the trophotaeniae, and a maternal component, the ovarian lining. The latter was examined by transmission electron microscopy, scanning electron microscopy, and light microscopy in both gravid and nongravid ovaries of the viviparous goodeid fish, Ameca splendens. The single median ovary of A. splendens is a hollow structure whose lumen is divided into lateral chambers by a highly folded longitudinal ovarian septum. Germinal tissue occurs within folds of the ovarian lining that extend into each of the two lateral chambers. Matrotrophic embryonic development takes place within ovarian chambers. During gestation, the lining of the ovarian lumen is in direct apposition to body surfaces and trophotaenial epithelia of developing embryos. The ovarian lining consists of a simple cuboidal epithelium, termed the internal ovarian epithelium (IOE), overlying a well-vascularized bed of connective tissue. Cells of the IOE are apically convex. Well-developed granular and agranular endoplasmic reticula and numerous large membrane-bound vesicles with electron-dense content occupy the apical cytoplasm of IOE cells. Two functional states of the same cell type are distinguished within the IOE. Phase I cells contain few, if any, large apically situated vesicles; Phase II cells contain many. Secretory products of the IOE are presumed to be an important source of nutrients for embryonic development. Structural and functional relationships of the IOE to the trophotaenial epithelium of developing embryos are discussed in relation to maternal-embryonic nutrient transfer processes.     

High‐resolution imaging of the actin cytoskeleton and epithelial sodium channel,CFTR, and aquaporin‐9 localization in the vas deferens

Vas deferens is a conduit for sperm and fluid from the epididymis to the urethra. The duct is surrounded by a thick smooth muscle layer. To map the actin cytoskeleton of the duct and its epithelium, we reacted sections of the proximal and distal regions with fluorescent phalloidin. Confocal microscopic imaging showed that the cylinder‐shaped epithelium of the proximal region has a thick apical border of actin filaments that form microvilli. The epithelium of the distal region is covered with tall stereocilia (13–18 µm) that extend from the apical border into the lumen. In both regions, the lateral and basal cell borders showed a thin lining of actin cytoskeleton. The vas deferens epithelium contains various channels to regulate the fluid composition in the lumen. We mapped the localization of the epithelial sodium channel (ENaC), aquaporin‐9 (AQP9), and cystic fibrosis transmembrane conductance regulator (CFTR) in the rat and mouse vas deferens. ENaC and AQP9 immunofluorescence were localized on the luminal surface and stereocilia and also in the basal and smooth muscle layers. CFTR immunofluorescence appeared only on the luminal surface and in smooth muscle layers. The localization of all three channels on the apical surface of the columnar epithelial cells provides clear evidence that these channels are involved concurrently in the regulation of fluid and electrolyte balance in the lumen of the vas deferens. ENaC allows the flow of Na⁺ ions from the lumen into the cytoplasm, and the osmotic gradient generated provides the driving force for the passive flow of water through AQP channels.     

Morphology of the bovine epididymis

The epididymis of the bull was divided into six regions, and morphological differences between regions were studied. The epithelium of all regions contained four cell types: principal and basal epithelial cells, and intraepithelial lymphocytes and macrophages. The epithelium of regions II-V also contained a few apical cells. Principal cells of all regions possessed an endocytotic apparatus including stereocilia underlain by canaliculi, coated vesicles, and subapical vacuoles (up to 1 micron in diameter); however, large vacuoles with a flocculent content and multivesicular bodies (up to 5 microns in diameter) were most numerous in regions II, III, and IV. The unique features of principal cells of region I were the presence of well-developed Golgi bodies, few lipid droplets, and whorls of smooth endoplasmic reticulum in the supranuclear cytoplasm. Numerous mitochondria, distended cisternae of rough endoplasmic reticulum, and dense granules characterized the infranuclear cytoplasm of the principal cells of regions II-VI; however, these features were more developed in region V. Apical cells were characterized by the apical location of the nucleus, many mitochondria in the apical cytoplasm, and few microvilli at the luminal border. Basal cells with few cytoplasmic lipid droplets were present throughout the length of the epididymis but appeared more numerous in region V. Intraepithelial lymphocytes were present at all levels of the epithelium but were never seen in the lumen. Intraepithelial macrophages containing heterogeneous granules, eccentric nuclei, and pseudopods were invariably seen near the basal area of the epithelium in all regions. These observations are discussed in an effort to define the role of each cell type in the epididymal epithelium.     

The brain structure of selected trypanorhynch tapeworms

The brain architecture in four species of tapeworms from the order Trypanorhyncha has been studied. In all species, the brain consists of paired anterior and lateral lobes, and an unpaired central lobe. The anterior lobes connect by dorsal and ventral semicircular commissures; the central and lateral lobes connect by a median and an X-shaped crisscross commissure. In the center of the brain, five well-developed compact neuropils are present. The brain occupies a medial position in the scolex pars bothrialis. The ventral excretory vessels are situated outside the lateral lobes of the brain; the dorsal excretory vessels are located inside the brain and dorsal to the median commissure. The brain gives rize four anterior proboscis nerves and four posterior bulbar nerves with myelinated giant axons (GAs). The cell bodies of the GAs are located within the X-commissure and in the bulbar nerves. Highly developed serotonergic neuropils are present in the anterior and lateral lobes; numerous 5-HT neurons are found in the brain lobes including the central unpaired lobe. The X-cross commissure consists of the α-tub-immunoreactive and 5-HT-IR neurites. Eight ultrastructural types of neurons were found in the brain of the three species investigated. In addition, different types of synapses were present in the neuropils. Glial cells ensheath the brain lobes, the neuropils, the GAs, and the bulbar nerves. Glia cell processes form complex branching patterns of thin cytoplasmic sheets sandwiched between adjacent neural processes and filling the space between neurons. Multilayer myelin-like envelopes and a mesaxon-like structure have been found in Trypanorhyncha nervous system. We compared the brain architecture of Trypanorhyncha with that of an early basal cestode taxon, that is, Diphyllobothriidea, and present a hypothesis about the homology of the anterior brain lobes in order Trypanorhyncha; and the lateral lobes and median commissure are homologous brain structures within Eucestoda.     

Morphological and biochemical analyses of the salivary glands of the malaria vector, Anopheles darlingi.

Adult Anopheles darlingi salivary glands are paired organs located on either side of the esophagus. The male glands consist of a single small lobe. The female gland is composed of two lateral lobes, with distinct proximal and distal portions, and a medial lobe. The lobes are acinar structures, organized as a unicellular epithelium that surrounds a salivary canal. The general cellular architecture is similar among the lobes, with secretory material appearing as large masses that push the cellular structures to the periphery of the organ. Cells of the proximal-lateral lobes show asynchronous cycles of secretory activity and contain secretory masses with finely filamentous aspect. In the distal-lateral lobes, cells display synchronous cycles of activity, and have a dense secretory product with mottled pattern. Cells of the medial lobe have secretory masses uniformly stained and highly electrondense. Biochemical analysis of the adult female salivary glands revealed apyrase, alpha-glucosidase and lysozyme activities. Alpha-glucosidase and lysozyme activities are detected mostly in the proximal lobes while apyrase is mainly accumulated in the distal lobes. This differential distribution of the analyzed enzymes reflects a specialization of different regions for sugar and blood feeding. Thus, the morphological differences observed in the lobes correlate with functional ones.     

Immunohistochemical studies on the spinal dorsal horn of the turtle Chrysemys d'orbigny.

Immunohistochemical methods were used to characterize some of the systems of nerve fibers occurring in the spinal dorsal horns of the turtle Chrysemys d'orbigny. Substance P (SP), calcitonin gene-related peptide (CGRP) and leuenkephalin (Enk) immunoreactive fibers were found concentrated in the superficial horn region, termed here synaptic field Ia. From this zone the immunoreactive fibers project to deeper dorsal horn regions. Comparison with histological images obtained after HRP labeling of dorsal root axons indicates that SP-, CGRP- and Enk-immunoreactive fibers are small-diameter primary sensory fibers entering the cord via synaptic field Ia. It is posulated here that these three substances may coexist in the same fibers. Enk-positive fibers also occur randomly scattered in the lateral funiculi, showing a conspicuous increase in density at the perimedullary plexus level. Tyrosine hydroxylase (TH) immunoreactive fibers were found in the more compact dorsal horn neuropil (synaptic field II) and also forming bilateral conspicuous bundles in the lateral funiculi. TH-immunoreactive cell bodies were found in the epithelium lining the central canal. Taking into account data derived from Golgi impregnated material it is proposed that they represent epithelial cells undergoing neural differentiation.     

The stomach of Oreochromis niloticus has three regions

The stomach of Oreochromis niloticus was divided into three distinct regions: initial, middle and terminal, corresponding roughly to the cardiac, fundic, and pyloric portions of the mammalian stomach. Grossly, the organ showed initial and terminal portions, the former connected to the distal part of the oesophagus and the latter to the proximal portion of the intestine. There was also a middle region, forming a large blind diverticulum communicating with the first two at their point of junction. The initial or cardiac region was shorter than the middle region but longer than the terminal one, and had a smooth surface devoid of gastric pits. The epithelium in this region was simple columnar devoid of goblet cells, with glandular regions in the lamina propria. The mucosa of the middle or fundic region had gastric pits lined by columnar epithelium, and simple tubular glands filled most of the lamina propria. The terminal or pyloric part of the stomach was very short and its mucosa was slightly folded and devoid of both gastric pits and mucous glandular cells. The lining epithelium of this portion of the stomach was simple columnar and a few goblet cells were seen at its junction with the first part of the intestine. The tunica muscularis of the stomach contained skeletal muscle in the initial and terminal regions, usually intermingled with smooth muscle fibres. Skeletal muscle fibres were also observed in the first portion of the small intestine, near the junction with the stomach.     

The normal development of the anorectum in the pig

The development of the anorectum was studied in forty-four embryos and foetuses of pig varying in length from 9 mm total length to 210 mm crownrump length and in three newborn pigs. The presence of some features during critical stages in the development of the cloaca in the pig such as an epithelial mass protruding into the dorsal cloaca near its intestinal orifice and distinct differences in the type of epithelium in different regions of the cloacal system greatly facilitated the study of the developmental process. Thus it could be established that a change in position of the dorsal cloaca and adjacent structures such as the distal part of the gut and the urorectal septum via the dorsal part of the cloacal plate towards the tailgroove is of major importance for the partition of the cloaca into a separate intestinal and urogenital division. A subsequent disintegration of the dorsal part of the cloacal plate results in two separate openings for both the systems at the same time. Disintegration of the ventral part of the cloacal plate leads only to a further widening of the external opening of the urogenital system. In the cloacal system three distinct zones were discerned, a dorsal and ventral cloacal and a cloacal plate region. From the dorsal cloacal epithelium the whole anorectal segment between the intestinal mucosa and the anal epidermis develops. The epithelium of ventral cloacal origin seems to disappear completely . Cloacal plate epithelium forms the epithelial lining of distal parts of the urogenital system. The penile urethra in the male is formed by a ventralward movement of the urogenital opening by the growing perineum and not by fusion of genital folds.     

Observations on the laternal vaginae and birth canals in the marsupials Isoodon macrourus and Perameles nasuta (Mammalia)

The laternal vaginae in the bandicoots Isoodon macrourus and Perameles nasuta wer long, straight and tabular, and consisted of a mascular sheath, an intermediate connective tissue layer and a luminal epithelium. The muscle layer had an inwardly projecting longitudinal ridge in I. macrourus but not in P. nasuta . In both species, a glassy layer was present immediately below the epithelium which was usually stratified columnar in type, although a non-keratinzing squamous type occured in small regions in some P. nasuta during pregnancy. The distance between the lateral vaginae in the birth canal region increased during pregnancy and reached a maximum at birth. The birth canal lacked an epithelial lining and was patent in some animals for more than half the lactation period. The allantoic stalks were often retained within the birth canal region throughout the lactation period and in some animals during the next pregnancy and even during the early part of the subsequent lactation     

Morphological and histochemical investigations of esophagogastric tract of a lizard, Laudakia stellio (Agamidae, Linnaeus 1758)

Histological structures of esophagus and stomach tissue samples of Lacerta stellio have been studied, and glycosaminoglycan (GAG) distribution has been histochemically determined. Histologically, esophagus and stomach of L. stellio are composed of four layers: mucosa, submucosa, muscularis mucosae and serosa. Mucosa of esophagus is covered by simple columnar ciliated epithelium with many mucous secreting goblet cells and contains branched tubular glands.Stomach of L. stellio is composed of fundus (oral and aboral) and pylorus regions. Mucosa is covered by columnar epithelium. Fundic glands are branched tubular glands while pyloric glands are usually simple tubular glands. In both regions of the stomach, glands are subdivided into three areas as base, neck and isthmus. Both in the esophagus and stomach, muscular layer is in the form of smooth muscle having inner circular and outer longitudinal layers.According to the results obtained by Alcian Blue (pH 5.8)/Periodic Acid Schiff staining, stomach is similar to esophagus in that neutral mucins and hyaluronic acid (HA) are dominant in isthmus and neck regions of gland tissue of stomach. In the base of the stomach, only neutral mucins have been observed. HA has been observed to be dominant in all other regions of both stomach and esophagus, along with some but not much sulphated GAGs.     

Ultrastructure of the anterior alimentary tract of infective-stage Wuchereria bancrofti (Nematoda: Filarioidea).

The anterior alimentary tract of infective-stage Wuchereria bancrofti is divided into the following segments: stoma or buccal capsule, muscular esophagus, glandular esophagus, esophageal-intestinal valve, and intestine. Invaginated external cuticle lines only the anterior stoma. External cuticle and esophageal lining are not continuous and are ultrastructurally distinct; the latter is compared morphologically to the amorphous component of elastin. The glandular esophagus is a composite structure of a stellate contractile epithelial core, surrounded by a sleeve of secretory epithelium. The glandular cytoplasm shows evidence of formation and release of dense secretory granules. At least 2 nerve cell bodies lie within the esophagus approximately 15 micrometer anterior to the esophageal-intestinal valve and their associated processes pass forward and backward through the contractile epithelium. Materials interpreted as ingested flight muscle mitochondria of the mosquito vector appear in various stages of degeneration within the intestinal lumen. It is suggested that, although simple by comparison to some other nematodes, the anterior alimentary tract of infective-stage W. bancrofti functions in the ingestion and breakdown of nutrient materials. The ultrastructure of the excretory cell likewise suggests a functional capability.     

Light and electron microscopic observation on the appearance of immunoreactive LHRH in perinatal rat hypothalamus

Summary The appearance and localization of LHRH were studied in the developing hypothalamus of perinatal rats using the unlabelled antibody method. By light microscopy, immunoreactive LHRH was first detected as brown dots on day 18.5 of gestation in the OVLT and on day 19.5 in the median eminence, respectively. When the median eminence was examined by the preembedding immunohistochemistry technique for electron microscopy, the occurrence of immunoreactive LHRH fibers could be demonstrated on day 18.5. These fibers were thin and very occasionally encountered near the surface of the lateral regions of the median eminence. The axoplasm contained a few immunopositive secretory granules and also extragranular immunoreactive products. With development, a gradual increase was noted both in number and size of nerve fibers with a concomitant accumulation of secretory granules within the axoplasm.A possible physiological significance of LHRH is discussed in relation to the onset of hypothalamo-hypophysial system in fetal life.     

A Golgi study of the hypothalamus of Actinopterygii

Summary The posterior hypothalami of the polypteriform, Calamoichthys, and of the teleost, Anguilla, were studied by means of the Golgi technique. In Calamoichthys, the lateral lobes are not developed and the median lobe is simple. In Anguilla, the median (tuberal) lobe shows lophodendritic, CSF-contacting cells and horizontal cells in the periventricular grey and some reticular elements directed toward the cell-poor lateral areas. In the lateral lobes the periventricular grey is formed by multipolar neurons and a diffuse population of multipolar cells of uncertain identity. The nucleus diffusus lobi lateralis is formed by scarce multipolar neurons, often placed next to the external surface of the brain. The organization of the lateral lobes in Actinopterygii is reminiscent of highly developed integrative regions.Work performed under CNR Project Biology of Reproduction     

The effect of lobar obstruction on regional perfusion in the intact dog.

The effect of acute obstruction of the right lower lobes (RLL) on the relative perfusion of different lung regions was studied using Xenon-133 in anesthetized artificially ventilated supine dogs. When the RLL were obstructed at functional residual capacity (FRC) and the rest of the lung was inflated to a transpulmonary pressure of 10 or 20 cm H2O (1 cm H2O = 94.1 N/m2), relative perfusion increased within 10 s to the obstructed lobes by 59 and 92%, respectively. The increase was less marked but still present (17 and 42%, respectively) when obstruction was maintained for 15 min, at a time when arterial hypoxemia had occurred. Hence, there was increased perfusion to an obstructed hypoxic region. The perfusion distribution correlated with the difference in alveolar pressure between the obstructed lobes and the unobstructed lobes such that relative perfusion was always increased to the low alveolar pressure region.     

Stomach of Aplysia depilans (Mollusca,Opisthobranchia): a histochemical,ultrastructural, and cytochemical study

We report the results of a morphological, histochemical, and cytochemical characterization of the Aplysia depilans stomach, an organ little studied in opisthobranchs. Very thin ciliated cells with microvilli on their apical surfaces are predominant in the epithelium lining the lumen of the stomach. Many lysosomes with a strong arylsulphatase activity were present in the apical regions of these cells that could also contain some lipid droplets and glycogen. Small peroxisomes were observed, usually around lipid droplets or mitochondria. Bottle-shaped secretory cells are very common in this epithelium and produce a secretion rich in proteins and acidic mucopolysaccharides. Most of the cytoplasm of these mucus-producing cells was filled with a very high number of granules and the nucleus is dislocated to the basal region. Cisternae of rough endoplasmic reticulum were abundant around the nucleus and several Golgi stacks were also present in this area. In spite of the variation in the electron density of the granules, only one type of secretory cell seems to be present in the stomach epithelium, since granules with very different electron densities were frequently found in the same cell. A few neurons were also found in the stomach epithelium of this species. Fibrocytes, muscle cells, nerves, and amebocytes were observed in the connective tissue of the stomach wall.     

Specificity of histological interrelations of cardial glands of the esophagus with its multi-layer lining]

Bioptates obtained from 163 mature persons have been studied, using spiral sections. When the conditions of functioning are altered (at the gastro-esophageal reflux) the organ's integument can destroy, but the defects formed in the lining are covered with a simple cylinder epithelium of the cardial glands. A connection between Barrett's syndrome in the esophagus with its cardial gland is demonstrated. The most widely distributed histological forms of Barrett's esophagus are described.