脉红螺消化系统的形态学研究

脉红螺消化系统由十二个器官组成。其消化管壁都由粘膜层、粘膜下层、肌层和外膜四层结构构成。作者对消化腺的细胞进行了较详细的描述,并利用组化方法测定消化腺细胞中含有的酶类。作者还对部分器官的超微结构进行了观察。     

皱纹盘鲍消化腺细胞类型和分泌产物

对皱纹盘鲍消化腺进行了组织学、组织化学、超微结构及酶活性测定等研究。消化腺由消化细胞和嗜碱性细胞组成。消化细胞能内吞腺管腔内的外源性物质,细胞内充满大量与异噬功能有关的囊泡。消化细胞具有内吞和细胞内消化、分泌、贮存等功能。嗜碱性细胞含有发达的粗面内质网以及许多含铁的折光小体,具有分泌和贮存金属离子的功能。消化腺还呈现多种水解酶活性。     

The effects of naphthalene on the ultrastructure of the hepatopancreas of the fiddler crab, Uca minax

The hepatopancreas of the red-jointed fiddler crab, Uca minax, is a bilateral evagination of the midgut, composed of numerous blind-ending tubules. Groups of these tubules empty into collecting ducts which join to form the main hepatopancreatic duct. Ultrastructural examination of tubules from the hepatopancreas of adult fiddler crabs revealed four major cell types, designated as E, R, B, and F cells. The E cells were found at the apex of the tubule and were assumed to serve as meristematic tissue. The R cells were most numerous and were scattered along the length of the tubule. Characterized by extensive smooth and rough endoplasmic reticulum and abundant lipid and glycogen reserves, the R cell was assumed to function in absorption and storage of the organic products of digestion. The B cells were recognized by the presence of a single, large apical vacuole that likely functioned in the secretion of digestive enzymes into the lumen of the hepatopancreas. The F cells, which contained extensive amounts of rough endoplasmic reticulum, were believed to be responsible for the synthesis of digestive enzymes. Electron microscopy of the hepatopancreas of crabs exposed to naphthalene for 5 days revealed that those cells with abundant membrane lipids (F cells) and abundant storage lipids (R cells) were most altered while those cells having little membrane or storage lipids (B and E cells) were only slightly altered. Furthermore, alterations in the F and R cells were not uniform along the length of the tubule, but increased in severity toward the proximal end.     

Changes in the digestive gland of the loliginid squid Sepioteuthis lessoniana (Lesson 1830) associated with feeding

Changes associated with feeding in the histological and cytological structure of the digestive gland of the loliginid squid Sepioteuthis lessoniana were examined, along with the nature of both the intracellular and extracellular enzymes produced by the gland. The timing of the release of the extracellular enzymes during the digestive cycle was also determined using a quantitative experimental program. Like that of all coleoid cephalopods, the digestive gland was characterised by one type of cell with several functional stages. As is the case for other loliginid squids, however, the digestive cells did not contain the large enzyme-carrying boules that characterise the digestive glands of most cephalopods. Instead, smaller secretory granules were found in the digestive cells and these may be the enzyme carriers. The prominent rough endoplasmic reticulum, large mitochondria and active Golgi complexes present in the digestive cells are characteristic of cephalopods and indicate a high metabolic activity. Like that of other cephalopods, endocytotic absorption of nutrients and intracellular digestion occurs in the digestive gland of this squid. From quantitative and qualitative examinations of structural changes in the digestive gland of S. lessoniana after feeding, a schedule of its function during the course of digestion was proposed. This indicated that digestion was very rapid, being completed in as little as 4 h in S. lessoniana. Extracellular digestive enzymes were only released after the first hour following feeding, which implies that they are stored in the stomach between meals to increase digestive efficiency.     

Fine structure of the midgut gland of Phalangium opilio (Chelicerata,Phalangida)

Summary The fine structure of the midgut gland and the changes in composition associated with the digestive activity were examined in Phalangium opilio. In the epithelium four different types of cells are present: ferment cells, resorption cells, and digestion cells which probably turn into excretion cells, as can be seen by many intermediate stages. Ferment cells are found only in the midgut gland and in no other epithelia; therefore they should be regarded as a cell type. The relationship between digestion and resorption cells is not yet clear. No regeneration zone or single regeneration cells could be identified.The ultrastructural changes in these different cells during digestion are described, and their functional aspects are discussed. A hypothetical digestive cycle is constructed from these data. The results are compared with those on other chelicerate midgut glands.     

凹耳蛙消化道组织学和嗜银细胞形态观察

为了揭示凹耳蛙(Odorrana tormota)消化道的基本特征,运用石蜡切片法和龙桂开银浸法对凹耳蛙消化道组织学结构及嗜银细胞的形态与分布密度进行了观察。结果显示:①凹耳蛙的胃壁具明显的纵行皱襞和胃小凹,胃腺发达,小肠可分为十二指肠和回肠,杯状细胞分散在十二指肠上皮细胞之间,十二指肠中未见十二指肠腺分布。②凹耳蛙嗜银细胞见于消化道全长,呈毛笔头样、锥体形、梭形、椭圆形和长条形等;幽门腺上皮和十二指肠绒毛上皮中的嗜银细胞具指向腺泡腔或肠腔的突起,提示其可能具有腔分泌的功能。嗜银细胞的分布密度胃幽门部最高,十二指肠和胃体其次,食道最低。据此认为胃既是凹耳蛙的主要消化器官,也是消化道中主要的内分泌器官;十二指肠是凹耳蛙消化道中的主要吸收部位,同时也具有内分泌功能;消化道嗜银细胞具有内分泌的功能,还可能具有腔分泌的功能。     

Ultrastructural changes in the abdominal midgut of the mosquito, Culiseta melanura, during the gonotrophic cycle

Abdominal midguts of the mosquito, Culiseta melanura, were examined by light and electron microscopy 1 hr-14 days days after blood feeding. Epithelial cells were drastically altered from columnar to squamous in form after engorgement, and returned to columnar by day 4 after feeding. Accumulation of mitochondria along brush borders of digestive cells, followed by the appearance of large secondary lysosomes, accompanied blood digestion. Evidence was obtained that myelin-like material in the lysosomes, probably the result of mitochondrial autolysis, is extruded into the lumen. Digestive cells resumed their pre-blood meal appearance by 10-14 days post-engorgement. Regenerative cells were scattered throughout the basal portion of the epithelium, along with endocrine cells. Other midgut cells containing large, microvilli-lined apical cavities were identified in most specimens. No evidence of division or differentiation was obtained for any cell types.     

Cloning of cDNAs and hybridization analysis of lysozymes from two oyster species, Crassostrea gigas and Ostrea edulis

In bivalve molluscs including oysters, lysozymes play an important role in the host defense mechanisms against invading microbes. However, it remains unclear in which sites/cells the lysozyme genes are expressed and which subsequently produced the enzyme. This study cloned lysozyme cDNAs from the digestive organs of Pacific oyster Crassostrea gigas and European flat oyster Ostrea edulis. Both complete sequences of two oysters' lysozymes were composed of 137 amino acids. Two translated proteins present a high content in cysteine residues. Phylogenetic analyses showed that these oysters' lysozymes clustered with the invertebrate-type lysozymes of other bivalve species. In the Pacific oyster, lysozyme mRNA was expressed in all tissues except for those of the adductor muscle. In situ hybridization analyses revealed that lysozyme mRNA was expressed strongly in basophil cells in the digestive gland tubule of C. gigas, but not in digestive cells. Results indicated that the basophil cells of the oyster digestive gland are the sites of lysozyme synthesis.     

Absorption of ferritin by cells of the digestive gland in Nassarius tegula (Gastropoda : Prosobranchia)

Within 12 min after the prosobranch snail, Nassarius, begins feeding on ferritin-labeled food, ferritin reaches the lumen of the digestive gland and is absorbed by the digestive cells lining the gland. Within the digestive cells, the ferritin is present in coated pinocytotic vesicles, in microvesicles and in macrovesicles. It is probable that ferritin (and components of the food as well) progresses rapidly in order from the gland lumen to the pinocytotic vesicles to the microvesicles to the macrovesicles. The macro vesicles are presumably an important site of intracellular digestion.     

Venom gland ontogeny in Formicinae, with special reference to the pulvinate convoluted gland (Hymenoptera, Formicidae)

 The primordia of the sclerites associated with the venom gland appear in third-stage larvae. The study aims to link the structure and function of this specialised venom structure in Formicinae, together with glandular ontogeny, and puts emphasis on the relevance of the distinguished glandular subunits contributing to the final secretion. The most conspicuous changes in glandular development occur in the pharate pupa. At this stage, all subunits of the venom gland (the tubule, the convoluted gland and reservoir) are visibly present. Formation of the glandular cuticle starts around day 4 of the pupal stage. Luminal cells in the convoluted gland are provided with abundant free ribosomes and apical microvilli that remain during adult life. Stacks of granular endoplasmic reticulum are also frequently found in these cells. The convoluted gland contains relatively few scattered secretory cells, belonging to type 3 according to Noirot and Quennedey (1974), which contain electron-dense material in their extracellular spaces during adult life. These cells strongly contrast with the apparently general non-glandular nature of the convoluted gland tubule. Histochemical investigation of the secretory cells in the pulvinate convoluted gland reveals that these cells contain lipoid material, most likely to correspond with lipoids demonstrated in earlier chemical analyses. This lipoidal material in minor quantities strongly contrasts with the bulk of acid constituting the secretion. The substances produced in the convoluted gland could act as insulators, thus protecting the insect against its corrosive venom. Accepted: 28 April 1998     

Seasonal variation of xanthine oxidoreductase activity in the digestive gland cells of the mussel Mytilus galloprovincialis: a biochemical, histochemical and immunochemical study

The activity and the tissue distribution of the oxygen radical producing enzyme xanthine oxidoreductase (XOR) were measured in the digestive gland of the common marine mussel Mytilus galloprovincialis Lmk along an annual cycle. No xanthine oxidase (XOX) activity could be measured, the enzyme only displaying xanthine dehydrogenase (XDH) activity in all the cases. This is interpreted as a mechanism to avoid the harmful effects of the oxygen radicals that would be produced by XOX during periods following anoxic conditions at low tide. The highest XDH activities coincided with the late spring/early summer months, the activity maxima being recorded from May to July. Histochemically XOR activity was very pronounced in duct and stomach epithelial cells as well as in the surrounding connective tissue and hemolymph vessels, the activity increasing towards the summer months. These seasonal variations in XDH or XOR activities are possibly linked to hormonal changes governing the reproductive cycle and to changes in food availability. The localization of the protein in the connective tissue lining the hemolymph vessels was confirmed immunohistochemically using a polyclonal antibody against rat liver protein that cross-reacted specifically with a polypeptide of 150 kDa of molecular mass in homogenates of the digestive gland. This polypeptide was linked to cytosolic fractions isolated by differential centrifugation from mussel digestive glands. In paraffin sections the antibody labeled the digestive cells of digestive tubules, as well as the connective tissue surrounding the hemolymph vessels, gonadal follicles, digestive epithelia and certain protozoan parasites. Taken together our results suggest that in the digestive gland of bivalve molluscs XOR is involved in the metabolism of purines and in the scavenging of oxygen free radicals.     

An Unusual Sexually Dimorphic Mosaic Distribution of a Subset of Kallikreins in the Granular Convoluted Tubule of the Mouse Submandibular Gland Detected by an Antibody with Restricted Immunoreactivity

The granular convoluted tubule of the mouse submandibular gland contains a wide variety of biologically active proteins, including several kallikreins. The tubule is under multihormonal regulation, and is sexually dimorphic, being larger in males than in females. Correspondingly, levels of its various protein secretory products are more abundant in males than in females. However, isoelectric focussing studies show that the true tissue kallikrein, mK1, is more abundant in the female than in the male submandibular gland. In this study, an antiserum was prepared with restricted immunoreactivity for mouse mK1, and possibly other kallikrein family members of low abundance in the mouse submandibular gland, and used for the immunocytochemical staining of the granular convoluted tubule cells in the submandibular gland of adult male and female mice, by indirect enzyme-labeled and immunogold-labeled antibody methods for light and electron microscopy, respectively. The distribution of immunoreactive tubule cells showed an unusual sexual dimorphism. In males only a few scattered slender tubule cells were strongly stained, while the more typical large tubule cells were only occasionally weakly positive, and many of them were not stained. By contrast, in females slender tubule cells were not seen, and about two thirds of the more typical tubule cells showed moderate to strong immunostaining. Immunoelectron microscopy revealed that immunostaining was confined to the secretion granules in granular convoluted tubule cells in both sexes. The slender tubule cells of males had many strongly stained small apical secretion granules and occasional basal infoldings; in the weakly positive larger more typical tubule cells not all secretion granules were positive, and there was intergranular variation in the intensity of staining of positive granules. In females, although more tubule cells were stained, intergranular variations in staining intensity were also noted. In both sexes, many tubule cells did not contain any secretion granules that showed immunogold labeling for kallikreins. These findings establish that, in contrast to the situation for the majority of granular convoluted tubules proteins, mK1 and possibly other minor kallikrein family members are more abundant in the granular convoluted tubules of female mice, and that there is considerable variation in the content of these kallikreins not only between different tubule cells, but also in individual secretion granules in any given tubule cell in either sex.     

ULTRASTRUCTURAL LOCALIZATION OF COMPLEX CARBOHYDRATES AND PHOSPHATASES IN DIGESTIVE GLAND CELLS OF FEEDING AND HIBERNATING SNAILS, HELIX LUCORUM (GASTROPODA: HELICIDAE)

The digestive gland of normally-fed snails Helix lucorum, aswell as that of snails which had hibernated for 4 months wereexamined by the use of cytochemical techniques for detectionof acid and alkaline phos-phatase, as well as of periodate-reactive(PA-TCH-SP technique), sulfated (HID-TCH-SP technique) and carboxylatedcarbohydrates (LID-TCH-SP technique). The cytochemical resultssupport the hypothesis of intracellular digestion via lysosomalactivity of material taken up by endocytotic processes by thecells of the digestive gland. Four months hibernation did notaffect the intracellular distribution of polysac-charides andphosphatases in the cells of the digestive gland of H. lucorumcompared to that in the control snails. In addition, hibernationaffected the percentage of the calcium cells which significantlyincreased compared to the non-hibernating snails, whiie thepercentages of the digestive and excretory cells remained almoststable. However, the periodate-reactive sulfated and carboxylatedpolysaccharides of the digestive gland cells decreased in thehibernated snails compared to the controls. The results suggestthat the cytochemistry of periodate-reactive, sulfated and carboxylatedpolysaccharides used in the present study could, also, be appliedto the study of lysosomal activities. (Received 1 October 1991; accepted 4 December 1991)     

An examination of the role of the digestive gland of two loliginid squids,with respect to lipid: storage or excretion?

The role of the digestive gland, with respect to non-structural lipid, was examined using proximal analysis, histochemistry and quantitative histological techniques in the tropical loliginid squids Sepioteuthis lessoniana (Lesson) and Photololigo sp. The digestive gland of both species was characterized by large and numerous lipid droplets in the apical portion of the digestive cells and very few in the basal portion. The apical lipid droplets were released into the lumen of the gland and subsequently rapidly removed. Despite the numerous large apical lipid droplets, the lipid concentration in the digestive glands of S. lessoniana and Photololigo sp. was lower than that reported for most squid species. There was no relationship between lipid concentration and stage of digestion, suggesting that lipid is not stored in the gland after a meal. There was also no relationship between lipid concentration and the sex of an individual or stage of reproductive maturity, suggesting that these squids are not storing lipid in the digestive gland for use in fuelling reproductive maturation or providing an energy source for oocytes. I believe this study is the first to combine proximal analysis and quantitative histological techniques to examine the role of the squid digestive gland with respect to non-structural lipids. The results indicate that the digestive gland of these tropical loliginid squids is excreting, not storing, excess dietary lipid.     

Fine structure and function of the digestive cell of Sepia officinalis (Mollusca: Cephalopoda)

The post–embryonic development of the digestive gland has been studied by light and electron microscopy on animals reared in the laboratory. The gland reaches its "adult" structure around the end of the first month after hatching.
The infrastructural changes of the digestive gland have been followed during digestion at various ages (5,10,20,30 days and "adult"); ferritin was used for a tracer to study absorption.
These experiments have produced evidence of endocytosis intake of large proteins and further intracellular digestion inside the digestive cell. The residues of digestion are excreted in a "brown body" while the metabolites are used in new syntheses for the cell itself. These results demonstrate that "ancestral" digestive processes have been kept in at least one cephalopod.     

Pharyngeal and Gastrodermal Ultrastructure of Prorhynchus stagnalis Schultze, 1851 (Turbellaria,Lecithoepitheliata)

The digestive tract of a freshwater Lecithoepitheliata turbellarian, Prorhynchus stagnalis, has been studied at the ultrastructural level. The buccal tube connecting the mouth opening to the pharynx is lined by an insunk epithelium, and is provided with two kinds of secretory cells. The bulbous pharynx itself, typical of the genus, is a highly muscular organ, also lined internally by an insunk epithelium; it also bears at least two different types of gland cells. Externally the pharynx is enveloped by a thin, flat epithelium. The gastrodermis consists of phagocytes and Minotian gland cells, as typical for most Tricladida. No ciliary covering was observed along the whole digestive system; instead, phagocytic cells have long microvillar projections. Preliminary attempts to follow the digestive process using external markers and cytochemical reaction for acid phosphatase were successful in demonstrating endocytic activity in the phagocytes. These data, besides being a contribution to morphology and systematics, also speak in favour of the general digestive theory of Turbellaria proposed by Jennings and serve as a starting point for experimental studies on intracellular digestion within the Lecithoepitheliata.     

Histopathology of the digestive gland of the bivalve mollusk Crenomytilus grayanus (Dunker, 1853) from southwestern Peter the Great Bay, Sea of Japan

The histomorphology of the digestive gland of the bivalve mollusk Crenomytilus grayanus from Sivuchya Bay, which is located in the southwest of Peter the Great Bay and subjected to the effect of polluted waters of Tumannaya River, was studied. Pathological changes of the digestive tubules, channels, and connective tissue of the gland were recorded in all the mussels studied. The epithelium of the tubules and channels was characteristic with erosive disturbances and by heavy vacuolization of digestive cells; connective tissue of the gland was specified by cells with lipofuscin (granulocytomes) and by foci of cells necrosis and lysis. Nervous fibers running in the gland were swollen in some mollusks. Strongly basophilic spherical formations, presumably one of the development stages of a parasitic plasmodium, were found in the granulocytomes and among vesicular cells of connective tissue of all the mussels. It was concluded that pathological changes in digestive gland of Gray’s mussel might be caused by chronic pollution of the bay and by parasitic invasion.     

Microstructural and histochemical advances on the digestive gland of the common cuttlefish,Sepia officinalis L.

The cephalopod digestive gland is a complex organ that, although analogous to the vertebrate liver, has additional functions, with special (albeit not exclusive) note on its active role in digestion. Although the structure of the digestive cell and its main constituents are well known (among which “boules” and brown bodies are distinctive features), histological details of other cell types and the general structure of the digestive gland need still further research. By a thorough combination of histological and histochemical techniques, it is shown that the digestive gland diverticula of the common cuttlefish (Sepia officinalis L.) are comprised of three essential cell types: digestive, basal and excretory. Basal (“pyramidal”) cells are multi-functional, being responsible for cell replacement and detoxification, mainly through the production of calcic spherulae containing metals like copper and lead in a complex organic matrix of proteins and ribonucleins. Since copper- and lead-positive spherulae were almost absent from other cell types and lumen of the tubules, it appears that controlled bioaccumulation of these metals, rather than excretion, is the main detoxification mechanism. The results show that the organ is crossed by an intricate network of blood vessels, especially arteries and arterioles, whose contents share histochemical properties with a particular set of “boules” that are shed into the lumen of diverticula for elimination, suggesting that the organ actively removes unwanted metabolites from the haemolymph. Conversely, the rarer excretory cells appear to be specialized in the elimination of salts. Although the exact nature of many excretory and secretory products, as the metabolic pathways that originate them, remain elusive, the findings suggest an intricate interaction between the different cell types and between these and the surrounding media: haemolymph and digestive tract.     

The labial gland system of larvae of the imported fire ant,Solenopsis invicta Buren

Summary The authors describe the ultrastructure of the labial gland system in imported fire ant larvae, Solenopsis invicta Buren and present an enzyme analysis of enzymes in labial-gland secretions and midgut contents. The tubes of the labial gland produce and secrete a proteinaceous substance rich in digestive enzymes. The narrow cells of the reservoir of the gland have little or no secretory function but the lumen stores the proteinaceous secretion. The labial-gland enzymes include proteases and amylases, which function in extraintestinal digestion of solid food placed on the anteroventral body region of 4th-instar larvae by adult workers. The midgut contains proteases, amylases, and upases. Lipids appear to be predigested by the workers before being fed to the larvae.Approved as TA 15262 by the Director of the Texas Agricultural Experiment Station in cooperation with ARS/USDA. Supported by the Texas Department of Agriculure interagency agreement IAC-0487 (78-79)We would like to thank Rosemary Kamas, Dr. John Mirenda, and Mike Strand for their help in dissections of larvae and Dr. Howard Williams for his advice and suggestions