龟足消化系统形态和组织学特点

应用光学显微镜观察龟足（Capitulum mitella）消化系统的形态和组织结构。龟足的消化系统包括消化腺和消化道。消化腺一对,呈长囊状,含有分泌细胞（B细胞）、吸收细胞（R细胞）、储存细胞（F细胞）和胚细胞（E细胞）4种类型细胞。消化道呈U型,由口、食道、胃、肠、直肠和肛门组成,各部分的结构由内到外可分为黏膜层、黏膜下层、肌层和外膜4层。口器为咀嚼型,包括一片上唇、一对触须、一对大颚以及两对小颚。食道细短,具几丁质层但无基膜,管壁向腔内突起形成明显的纵褶突;食道前段的环肌特别发达,同时独有放射肌。胃略呈球袋状,肠较长;胃和肠的组织结构相似,没有几丁质层,上皮细胞都有发达的微绒毛。直肠细长,外膜分布有16组纵肌;直肠前段的组织结构与胃、肠相似,而直肠后段有几丁质层覆盖,黏膜层、黏膜下层、肌层和外膜渐退化,16组纵肌渐发达。肛门16组更加发达的纵肌挤入上皮细胞下方,在外膜外另出现一层明显的环肌。龟足消化道各部分的组织结构差异明显,反映了它们功能的差异。     

东方铃蟾消化道组织学的初步研究

采用组织学方法对东方铃蟾的消化道进行了研究。结果表明:肠分为十二指肠、空肠和大肠。消化道管壁由粘膜层、粘膜下层、肌层和浆膜层构成。食道、胃和肠均为单层柱状上皮。胃和十二指肠的粘膜皱褶最丰富。食道腺为复泡状腺,胃腺属于单管状腺,肠的各段无多细胞腺体,但空肠和大肠有丰富的杯状细胞。肌层均为平滑肌,内层环肌较厚,外侧纵肌较薄,其中大肠的外侧纵肌最发达。     

桃小食心虫幼虫的消化道和马氏管的显微结构观察

利用光学显微镜和扫描电子显微镜,在形态学和组织学水平上研究_『桃小食心虫 Carposina sasakii 幼虫消化道和屿氏管的结构.桃小食心虫幼虫消化道由前肠、中肠和后肠组成.前肠细短,肌肉层薄.前肠与中肠交界处有突出的胃盲囊.中肠长且粗大,内有围食膜,肠壁细胞较大,外层为发达的环肌和纵肌.后肠上皮细胞内陷很深.6根念珠状的马氏管位于中、后肠分界处.     

石磺消化系统的组织学观察

对石磺消化系统各部分结构进行组织学观察.石磺的消化系统由消化道和消化腺两部分组成.消化道包括口、食道、贲门胃、幽门胃、中肠和后肠,不具吻;消化腺包括肝胰腺、唾液腺和肛门腺.在光学显微镜下,消化道由粘膜层、粘膜下层、肌层和外膜4层组成;肌层主要为环肌,粘膜层主要为柱状细胞.肝胰腺甚为发达,组织结构显示肝胰腺由很多分支的腺管组成,腺管由腺细胞、分泌细胞等组成.唾液腺和肛门腺发达.     

黄脸油葫芦消化道和马氏管的组织学观察

应用石蜡切片技术对黄脸油葫芦Teleogryllus emma(Ohmachi and Matsumura)成虫消化道和马氏管的显微结构进行观察。消化道由前肠、中肠和后肠3部分组成:前肠由内向外可分为6层:内膜、肠壁细胞层、底膜、纵肌、环肌和围膜;中肠组织结构也分为6层,即由内向外依次为围食膜、肠壁细胞层、底膜、环肌、纵肌和围膜;后肠的组织结构与前肠基本相似,但内膜比前肠的薄,且肌肉的排列较前肠不规则,与中肠的肌肉排列相似,即环肌在内,纵肌在外。消化道各部位的结构差异与功能有密切关系。马氏管管壁由8个左右形状多变并具有显著细胞核的大形的单层上皮细胞组成。     

宽体沙鳅消化系统的结构

运用形态解剖和组织学方法对宽体沙鳅消化系统进行了研究.宽体沙鳅的胃呈U形;消化道较短,为体长的1.02±0.05倍.咽部粘膜层味蕾发达;未见食道纵肌层;胃分贲门部、盲囊部和幽门部,贲门部具胃腺,盲囊部环肌层发达,幽门部肌肉层3层,呈纵-环-纵排列,幽门括约肌发达;肠各段组织结构无明显差异;肝脏2叶,左叶发达;胰腺组织弥散在肝、脾、胃、肠等的系膜上或随血管的分支进入肝脏组织内.     

美洲黑石斑鱼消化道的形态结构

采用解剖和光镜技术观察了美洲黑石斑鱼消化道的形态及组织学结构。消化道由口咽腔、食道、胃、肠构成。口咽腔较大,具颌齿、腭齿及犁齿;舌由基舌骨突出部分覆盖粘膜构成。食道、胃及肠均由粘膜层、粘膜下层、肌层及外膜构成。食道粘膜层绒毛分柱状上皮区及扁平上皮区,扁平上皮区表面为杯状细胞层;食道粘膜下层中有食道腺。胃呈V形,由贲门部、胃体部及幽门部组成,胃壁粘膜层上皮为单层柱状上皮,胃腺位于贲门部与胃体部的固有层中。肠细长,呈S型,由前、中、后肠构成,粘膜层向肠腔突起形成肠绒毛,粘膜上皮为单层柱状上皮,上皮游离面有微绒毛密集排列而成的纹状缘,上皮中含有杯状细胞,且杯状细胞的数量从前向后呈递减趋势;肠长/体长约为1.6。胃与小肠相接处有3对指状幽门盲囊,幽门盲囊的组织学结构与肠相同。     

太白蝎蛉消化道形态学与组织学研究

利用光学显微镜和扫描电子显微镜, 在形态学和组织学水平上研究了太白蝎蛉Panorpa obtusa Cheng成虫消化道的结构。结果表明： 蝎蛉消化道由前肠、中肠、和后肠组成。前肠包括咽喉、食道、和前胃, 但没有嗉囊,其中咽喉可分为骨化的前咽和附着扩肌的后咽（咽喉唧筒）; 前胃壁很厚,内膜上长有许多排列整齐、紧密的棕色胃刺,司过滤、暂时储存和磨碎食物的功能; 前肠末端有6个贲门瓣伸入中肠。中肠较长且膨大,其肠壁细胞由柱状细胞和再生细胞组成; 肠壁细胞外分别为环肌和纵肌,无胃盲囊,也未观察到围食膜。6根棕红色的马氏管位于中、 后肠分界处。后肠分为不对称的“V”字型回肠、环状结肠、以及膨大透明的直肠, 直肠内壁上有6个交替排列的直肠垫。最后简要讨论了蝎蛉消化道的结构与功能,及其在蝎蛉科昆虫分类中的意义。     

银鲳消化道形态与组织学结构特征及其消化酶活性

为了解银鲳(Pampus argenteus)消化道结构特点与其功能及食性的相关性, 采用解剖、石蜡切片、AB-PAS染色及酶活性检测技术对银鲳消化道的形态、组织结构、黏液细胞分布及消化酶活性进行研究。结果显示, 银鲳的消化道由口咽腔(舌)、食道侧囊、食道、胃及肠构成, 胃肠交界处有很多幽门盲囊。食道侧囊呈椭球形, 食道粗短, 胃呈U型, 肠有多个盘曲, 肠指数为2.03。舌上皮内有少量味蕾及较多黏液细胞。食道侧囊、食道、胃及肠均由黏膜层、黏膜下层、肌层及浆膜组成。食道侧囊内皱襞较发达, 被覆复层扁平上皮, 内含较多黏液细胞, 且以Ⅳ型为主, 皱襞顶端及侧面有内含角质刺的次级突起; 黏膜下层及肌层中有固定皱襞的骨质脚根; 侧囊内胃蛋白酶活性较高。食道内皱襞较高, 被覆复层扁平上皮, 内含较多黏液细胞, 且以Ⅳ型为主。胃内皱襞发达, 被覆单层柱状上皮, 未见黏液细胞分布; 胃腺发达, 胃内蛋白酶活性较高。肠道内褶襞多, 高度呈先下降后上升趋势, 黏液细胞密度前、中肠较高, 后肠较低, 且均以Ⅰ型为主; 肠道内胰蛋白酶、脂肪酶、淀粉酶及碱性磷酸酶活性较高。幽门盲囊组织结构与肠相似。银鲳的消化道结构特点、黏液细胞分布及消化酶活性与其功能及偏肉食的杂食性相适应。     

香鱼消化道及肝脏的形态结构特征

采用解剖及石蜡切片显微技术观察了香鱼消化道及肝脏的组织学结构。香鱼消化道由口咽腔、食道、胃及肠构成。口咽腔大且狭长,其底壁前部有一对粘膜褶,两颌边缘着生宽扁梳状齿,腭骨及舌骨具齿,犁骨无齿;舌由基舌骨突出部分覆盖粘膜构成,舌粘膜上皮为复层扁平上皮,含有较多的杯状细胞和味蕾。食道、胃及肠均由粘膜层、粘膜下层、肌层及外膜构成。食道粘膜层上皮为复层扁平上皮,杯状细胞发达。胃呈V形,由贲门部、胃体部及幽门部组成,胃壁粘膜上皮为单层柱状上皮,贲门部与胃体部的固有层中有胃腺。肠较短,由前、中、后肠构成,肠壁粘膜上皮为单层柱状上皮,其游离面具微绒毛;上皮细胞间有杯状细胞。幽门盲囊有350～400条,其组织学结构与肠相同。肝脏单叶,外被浆膜;肝细胞形态不规则,肝小叶界限不明显。     

The digestive tract of the amberjack Seriola dumerili, Risso: a light and scanning electron microscope study

The histology of the digestive tract of the amberjack ( Seriola dumerili , Risso) was studied using light and scanning electron microscopy. The anterior oesophagus mucosa displays primary and secondary folds lined with a stratified squamous epithelium with fingerprint-like microridges which is substituted, on the top of the oesogaster folds, by a simple columnar epithelium with short microvilli. Only primary folds are present in the stomach. The anterior portion is rich in simple tubular glands, whereas the oesogaster and the pyloric region are devoid of them. Pyloric caeca and anterior and middle intestine mucosa display the same pattern of folding. The dominant cell type is the enterocyte, which exhibits larger and thinner microvilli in the caeca than in the intestine. The columnar epithelium of the rectum is replaced, in the anal sphincter, by a stratified flattened epithelium. Goblet cells are numerous throughout the whole length of the tract with the exception of the initial part of the oesophagus, the oesogaster, the stomach and the anal sphincter. Mucosubstances have been shown to vary in the different regions of the gut: acid mucines are found in the oesophagus, pyloric stomach, caeca, intestine and rectum, whereas neutral mucosubstances dominate in the anterior portion of the stomach. The muscularis is well developed throughout the length of the tract: two layers of striated muscle at the oesophageal level; two layers of smooth muscle in the stomach wall and three at the intestinal level.     

Feeding and gut physiology in Acanthopleura spinigera (Mollusca)

The morphology and histology of the alimentary canal of the rock chiton Acanthopleura spinigera are described and the ability of regions of the gut to digest specific substrates investigated. The oesophagus is produced into a pair of thin-walled lateral pouches, the salivary glands or "sugar glands" which empty into the stomach. Folds of the capacious stomach are almost obscured by the large digestive gland over which is coiled the intestine. Histologically the gut consists of an outer layer of connective tissue, an inner muscular layer and a ciliated epithelium which varies in thickness from one region to the next. Proteases are most active in the stomach, digestive gland and anterior intestine at pH 6·5 and in the posterior intestine at pH 7·5-8·5. The digestion of lipoidal substance was greatest in the stomach and digestive gland and least in anterior intestine. There was little increase in the amount of digestion product obtained after 20 hours incubation. All regions of the alimentary canal and salivary gland were capable of digesting carbohydrates except that many low molecular weight carbohydrates were digested by salivary gland extracts only. The amylases were most active at pH 6–6·5. It is concluded that digestive enzymes are distributed throughout the intestinal tract but the amount of enzyme present varies from region to region, and is greatest just after feeding.     

Morphological and histochemical peculiarities of the gut in the white sturgeon, Acipenser transmontanus.

The gut of adult sturgeon was examined. The oesophageal mucosa contained numerous caliciform cells, synthesizing both neutral and acidic glycoconjugates, the latter of the sialylated type. The deep tunica propria-submucosa contained lobules of multilocular adipose tissue, specially abundant during the cold season. The oesophageal tunica muscularis was made up of a large sheath of striated muscle fibres, arranged orthogonally to a thin, subserous smooth muscle layer. The siphon-shaped stomach showed a ciliated epithelium in cardiac and gastric proper gland zones, where tubular glands were present in the tunica propria. The columnar cells which composed the superficial epithelium and gastric pits were demonstrated to synthesize almost exclusively neutral glycoconjugates. Appendices pyloricae constituted a glandular body equipped with intestinal mucosa. The intestinal mucosa was organized in folds, containing numerous caliciform cells which synthesized neutral or acidic glycoconjugates, the latter either of the sialylated and sulphated type. The sulphoglycoconjugates were more abundant in the caliciform cells of the distal intestinal tracts. The tunica propria-submucosa of the spiral valve (medium intestine) contained lymphatic tissue and large lymphatic follicles. A muscularis mucosae was present only in the rectum, where in addition a peculiar granular cell type was present in the superficial tunica propria-submucosa, possibly related to defensive properties. The subserous connective tissue contained pancreatic lobules all along the stomach and intestine. The enteric nervous system showed some special aspects, the most intriguing of which was the presence of large, longitudinally oriented nerve bundles in the t. propria-submucosa of oesophagus and cardiac stomach. The nerve bundles contained, near unmyelinated nerves, some myelinated nerves, as well as neuronal bodies. Both these aspects are exceptional in vertebrates and obscure in their significance. The structural and histochemical aspects we here describe are in part different from those described for other fish. Some of these special features are possibly related with special functional roles, others require a deeper insight and different approaches to clarify them functionally.     

Morphology and histology of the alimentary tracts of ambassidae (Cuvier) (Teleostei) in relation to feeding

The gross morphology and histology of the alimentary tracts of three species of glassy perchlet; Ambassis productus, A. natalensis, and A. gymnocephalus from estuaries on the southeast coast of Africa were investigated. The anatomy of the digestive tracts in all three species was found to be similar. Well-developed dentition and pharyngeal teeth together with a distensible stomach and a low relative gut length (RGL) suggest a predatory and carnivorous habit for all three species. The relative gut lengths of Ambassis species from different estuarine systems are compared‥ Differences in RGL for A. productus and A. natalensis from the Kosi and St Lucia systems with fish from Mdloti estuary are discussed. It is suggested that decreased RGL for fish at Mdloti is attributable to decreased food availability and not to a lack in the calorific content of their diet. Histological investigation revealed the presence of the following regions: a pharynx; an oesophagus; a stomach differentiated into cardiac and pyloric regions; a duodenum or upper intestine; an ileum or lower intestine; and a rectum. Pyloric and rectal sphincters are present. The tunics of the above regions are described. The epithelium of the oesophagus contains taste buds and numerous mucus cells, and varies from stratified anteriorly to simple columnar posteriorly. The muscularis comprises dorsally and ventrally located inner muscle bundles and an outer circular layer. Both layers consist of striated fibres. Gastric glands are present in the mucosa of the cardiac stomach but are absent in the pylorus. Columnar absorbing cells and goblet cells are present in the epithelium of the upper and lower intestine. The rectum is distinguished from the intestine by the proliferation of mucous-secreting cells which are thought to aid defecation.     

Ultrastructural Studies of the Visceral Muscles of Chaetognaths

The visceral musculature of Chaetognaths was studied with special attention given to the digestive apparatus muscle. In the head the digestive apparatus muscle is relatively thick; individual muscles are difficult to distinguish at the anatomical level; in the anterior part of the oesophagus discontinuous bundles and layers of cross-striated fibers are found. As a group however, the oesophageal musculature completely covers the oesophageal epithelium. The prominent muscle layers around the oesophagus probably help to force food into the intestine against the turgor pressure of the trunk cavity which tends to collapse the intestine. Around the intestine the musculature is largely circular and smooth. The intestinal epithelium is ciliated despite its muscular covering. Muscle fibers are not individually innervated. They form myoepithelial structures with various intercellular junction types. In the intestinal muscle the fibers show myoendothelial-like junctions. Sphincters composed of myoepidermal cells surround the anus and the female gonopores. The somatic side of the general cavity is lined with a polymorphic squamous epithelium. Sometimes myoepithelial cells are found, with the occasional presence of extracellular matrix basal to the layer of the squamous epithelium. The ontogenetic relations between the polymorphic epithelium and the composite ‘mesenteries’ remain to be established. We have now some idea about the architecture of the body of Chaetognaths in relation to contractile structures.     

The microscopic anatomy of the oesophagus, stomach and intestine of the channel catfish, Ictalurus punctatus

An anatomical study of the digestive tract of the channel catfish revealed that the oesophageal mucosa was longitudinally folded and that secondary folds were occasionally located on the primary longitudinal folds. The infoldings were more numerous near the stomach. The stratified squamous epithelium covering the folds was made up of a basal layer, large mucous cells and simple squamous cells on the surface. The epithelium on the side of the folds consisted primarily of mucous secreting cells. Taste buds were observed between mucous cells on the apical portion of the oesophageal folds and were more prevalent in the cranial part of the oesophagus. The remaining layers of the oesophagus were: a lamina propria-submucosa, tunica muscularis and adventitia or serosa.
The J-shaped stomach had two regions: a large sac-shaped region containing gastric glands and a smaller, nonglandular pyloric region. The large rugae of the stomach became gradually smaller near the pylorus. There was a well developed pyloric sphincter. The mucosa included a simple columnar epithelium, a lamina propria and adventitia or serosa.
The intestine could be differentiated into a thick ascending segment, a descending segment, a thin convoluted segment and a thicker terminal segment, the rectum. Many mucosal folds containing branched villi characterized the ascending segment of the intestine. The descending and convoluted segments contained fewer folds with shorter and less-branching villi and were smaller in diameter and thinner walled. Descending and convoluted segments were also mildly convoluted and accounted for 80% of the total length of the intestine. An intestinal valve with a sphincter marked the beginning of the rectum. There was an approximately four-fold increase in the thickness of the tunica muscularis of the terminal segment of the intestine.     

白胸苦恶鸟消化管的组织学观察

采用石蜡切片技术对白胸苦恶鸟(Amaurornis phoenicurus)的消化道进行了组织学观察.结果表明,食管皱襞发达,黏膜上皮为复层扁平上皮,食管腺发达,颈段多于胸段,黏膜肌层为一层纵肌,厚约0.06 ～0.26 mm.肌层为一层厚约0.19～0.27mm的环肌.腺胃被覆单层柱状上皮,固有层内有单管腺和复管腺两种腺体,单管腺仅深约0.11 ～0.20 mm;复管腺厚约1.19～1.26 mm,占管壁的77.8％ ～80.4％.肌胃的类角质层发达,厚约0.16～0.24 mm.肌胃腺呈管状,与类角质层突起形成皱襞.肌层发达,由内环外纵两层平滑肌构成.肠绒毛无分支和中央乳糜管,十二指肠绒毛长而密集,空肠绒毛呈细长指状,直肠绒毛长且呈叶状.十二指肠与直肠肠绒毛内有大量致密淋巴小结,盲肠绒毛短,肠腺少.     

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.     

Ultrastructure of the foregut and associated glands of Calicotyle kröyeri (Monogenea: Monopisthocotylea)

The mouth, pharynx and oesophagus of Calicotyle are lined by syncytial epithelia, and there are numerous unicellular glands associated with the oesophagus. An infolding of unmodified external tegument lines the mouth cavity and is connected by discrete cytoplasmic processes to subjacent perikarya. It contains two types of secretory body and its luminal surface is invested with a finely filamentous coating. The pharynx and oesophagus are lined by irregularly-folded epithelia that are interconnected by a septate desmosome. Membranous inclusions distinguish the pharynx epithelium and there is a well developed basal lamina for insertion of the pharyngeal muscles. The oesophagus epithelium is perforated by the openings of the oesophageal glands. These lie in the surrounding parenchyma and produce a dense, membrane-bound secretion which is conveyed by duct-like extensions of the glands to the oesophagus lumen. The ducts are supported in places by microtubules and are anchored to the oesophageal epithelium by septate desmosomes. A septate desmosome also marks the junction between the epithelium and the gut caeca.