Histology and Ultrastructure of the Body Wall in the Phoronid Phoronopsis harmeri

The histology and ultrastructure of the body wall in Phoronopsis harmeriwere studied using light microscopy and TEM. The ectoderm epithelium of tentacles, anterior body region, and ampulla consists of monociliary cells. Gram-negative bacteria were found between microvilli, in the protocuticle of the anterior region, and in the ampulla. The epithelium of the posterior body region lacks both monociliary cells and bacteria. The bundles of nerve fibers run between the layer of epithelial cells and basal membrane. The musculature of the body wall comprises circular and longitudinal muscles. The circular muscle fibers are applied to the basal membrane and constitute a solid layer extending almost throughout the length of the body. This pattern is broken in the posterior body region, where there is no solid layer of circular musculature, and the latter is arranged in isolated muscle bands. In the ampullar (terminal) body region, the inversion of circular and longitudinal muscle layers takes place, so that the latter appears to be pressed against the basal membrane. The apical surfaces of longitudinal muscle cells bear cytoplasmic processes; some of the cells have a flagellum. The basal portion of the longitudinal muscle cells forms a cytoplasmic process containing bundles of tonofilaments. The processes of all cells making up the muscle bands are interwoven and anchored to the basal membrane.     

宽体金线蛭消化道的组织学观察

运用解剖学和组织学方法对宽体金线蛭消化道的结构进行了组织学研究。结果表明,宽体金线蛭的嗉囊向两侧伸出11对侧盲囊,第6对侧盲囊狭长并延伸到直肠两侧;咽主要由黏膜层、肌层和外膜构成,外膜几乎不可见;食道、嗉囊、肠和直肠管壁由黏膜层、黏膜下层、肌层和浆膜构成;咽和直肠的上皮具纹状缘。除肠外,其他消化道的上皮细胞均无发达的纤毛,且黏膜上皮皆为单层柱状上皮;除肠和直肠外,腺体及导管较少;直肠的黏膜肌层为内环外纵两层,其他各部均为纵行肌一层;消化道各部黏膜下层较发达;外膜为浆膜,与黏膜下层分界不明显。     

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 ultrastructure of the innervation of the intestinal wall in the teleosts Myoxocephalus scorpius and Pleuronectes platessa

Summary The innervation of the intestinal wall in the teleosts Myoxocephalus and Pleuronectes was examined electron microscopically. Two classes of axons can be identified. The first, which is in the majority, contains numerous 50–150 nm granular vesicles as well as some 40–50 nm agranular vesicles while the second contains predominantly the 40–50 nm agranular vesicles. Chromate/dichromate staining methods suggest that the first type is aminergic. Both types lie in close association with the perikarya of intrinsic myenteric neurons but only axons containing predominantly agranular vesicles have synaptic membrane specialisations. No axon bundles pass into the longitudinal muscle layer in Myoxocephalus gut and though some do in Pleuronectes, they do not closely approach the smooth muscle cells. Axons containing large granular vesicles lie in intimate contact with the myocytes of the circular muscle layer. Both axon types pass through the submucosa to form a plexus underneath the mucosal epithelium. Varicosities containing agranular or granular vesicles are separated from the epithelial cells by a gap of about 200 nm in which lies a basal lamina.     

Fine structure of the midgut of Sinopanorpa tincta (Navás) (Mecoptera: Panorpidae)

Fine structure of the midgut and degeneration of the midgut epithelium of the scorpionfly Sinopanorpa tincta (Navás) adults were investigated using light microscopy and scanning and transmission electron microscopy. The results show that the tubular midgut lacks gastric caeca and is composed of an outer longitudinal and an inner circular muscle layer, a basal lamina, an epithelium and a lumen from the outside to inside. A peritrophic membrane was not found in the lumen. A mass of nodules was observed on the surface of the basal lamina. Three types of cells were recognized in the epithelium: digestive, secretory, and regenerative cells. The digestive cells contain irregular-shaped infoldings in the basal membrane and two types of microvilli in the apical membrane. The secretory cells are characterized by irregular shape and large quantities of secretory granules in the basal cytoplasm. The regenerative cells are triangular in shape and distributed only in the nodules. The epithelial cells are degenerated through programmed cell-death mechanisms (apoptosis and necrosis). The type, function, and degeneration of the epithelial cells of the midgut are briefly discussed.     

Scanning electron microscopy of the muscle coat of the guinea-pig small intestine

Summary We have studied the layers of the muscular coat of the guinea-pig small intestine after enzymatic and chemical removal of extracellular connective tissue. The cells of the longitudinal muscle layer are wider, have rougher surfaces, more finger-like processes and more complex terminations, but fewer intercellular junctions than cells in the circular muscle layer. A special layer of wide, flat cells with a dense innervation exists at the inner margin of the circular muscle layer, facing the submucosa. The ganglia of the myenteric and submucosal plexuses are covered by a smooth basal lamina, a delicate feltwork of collagen fibrils, and innumerable connective tissue cells. The neuronal and glial cell processes at the surface of ganglia form an interlocking mosaic, which is loosely packed in newborn and young animals, but becomes tightly packed in adults. The arrangement of glial cells becomes progressively looser along finer nerve bundles. Single varicose nerve fibres are rarely exposed, but multiaxonal bundles are common. Fibroblast-like cells of characteristic shape and orientation are found in the serosa; around nerve ganglia; in the intermuscular connective tissue layer and in the circular muscle, where they bridge nerve bundles and muscle cells; at the submucosal face of the special, flattened inner circular muscle layer; and in the submucosa. Some of these fibroblast like cells correspond to interstitial cells of Cajal. Other structures readily visualized by scanning electron microscopy are blood and lymphatic vessels and their periendothelial cells. The relationship of cellular elements to connective tissue was studied with three different preparative procedures: (1) freeze-cracked specimens of intact, undigested intestine; (2) stretch preparations of longitudinal muscle with adhering myenteric plexus; (3) sheets of submucosal collagen bundles from which all cellular elements had been removed by prolonged detergent extraction.     

Morphological Descriptions of the Esophagus of the Sea Bream (<Emphasis Type="Italic">Sparus aurata</Emphasis>, Linneaus 1758)

The current work prepared to describe the microscopic morphological appearance of the esophagus of the gilthead sea bream (Sparus aurata). The esophageal wall was organized into four tunica; mucosa, submucosa, muscularis and serosa. There are many goblets cells in the esophageal epithelium. The tunica muscularis is very thick and consisting of; an outer circular thick layer and an inner longitudinal layer of striated muscle. The presences of the many goblet cells help in the esophageal lubrication and protection. By the histochemical reactions with Alcian blue and PAS staining, the esopgaster secretory epithelium devoid from any goblet cells. There are many mucous droplets of the high electron density and the low electron density between surface epithelial cells within the goblet cells. The obtained results of the current investigation may help to understanding the physiology of the esophageal digestive functions in Sparus aurata.     

C-kit-immunopositive interstitial cells of Cajal in human embryonal and fetal oesophagus

Interstitial cells of Cajal (ICC) are morphologically and functionally intercalated between the elements of the enteric nervous system and the smooth muscle cells (SMCs) in the musculature of the digestive tract. Kit immunohistochemistry reliably identifies the location of these cells and provides information on changes in ICC distribution and density. Human oesophagus specimens (7 embryos, 23 fetuses at 7-27 weeks gestational age; both sexes) were exposed to Kit antibodies to determine ICC differentiation. Enteric plexuses were examined immunohistochemically by using anti-neuron-specific enolase, whereas the differentiation of SMCs was studied with antibodies against α-smooth-muscle actin and desmin. By week 7, c-kit-immunopositive cells were present along the entire oesophagus in the form of an uninterrupted layer around the myenteric plexus (MP) elements. From the beginning of the 3rd month, the number of ICC progressively decreased around the MP ganglia but increased within the muscle layers. Concomitantly, differences in the number and distribution of ICC were established in the various portions of the oesophagus: specifically, ICC were abundant in the lower portion, less numerous in the middle region and rare in the upper part. By the 5th month of development, the relationship as found in later developmental stages had been established: C-kit IR ICC were present within the circular muscle layer, within the longitudinal layer and in the connective septa surrounding the muscle bundles but were completely missing around the MP ganglia.     

Ultrastructure of midgut endocrine cells in the adult mosquito, Aedes aegypti

The ultrastructure of endocrine cells in the midgut of the adult mosquito, Aedes aegypti, resembled that of endocrine cells in the vertebrate gastro-intestinal tract. Midgut endocrine cells, positioned basally in the epithelium as single cells, were cone-shaped and smaller than the columnar digestive cells. The most distinctive characteristic of endocrine cells was numerous round secretory granules along the lateral and basal plasma membranes where contents of the granules were released by exocytosis. Secretory granules in each individual cell were exclusively of one type, either solid or 'haloed', and for all cells observed, the range in granule diameter was 60-120 nm. The cytoplasm varied in density from clear to dark. Lamellar bodies were prominent in the apical and lateral cellular regions and did not exhibit acid phosphatase activity. The basal plasma membrane was smooth adjacent to the basal lamina, whereas in digestive cells the membrane formed a labyrinth. Some endocrine cells reached the midgut lumen and were capped by microvilli; a system of vesicles and tubules extended from beneath the microvilli to the cell body. An estimated 500 endocrine cells were distributed in both the thoracic and abdominal regions of the adult midgut. In one midgut, we classified a sample of endocrine cells according to cytoplasmic density and granule type and size; endocrine cells with certain types of granules had specific distributions within the midgut.     

金丝猴食管和胃连接部的组织学研究

本文研究了金丝猴食管和胃连接处的组织结构。金丝猴的食管粘膜为典型的复民鳞状上皮,食管末端含有粘膜腺,粘膜表面有轻微的角质化。管壁外纵肌层有少量的横纹肌。与胃粘膜的连接均位于胃的贲门部以内,两种上皮的连接是突然的,不存在过渡。 贲门腺为少量的分枝管状腺,短而直,由粘膜细胞构成,对PAS染色呈阳性反应。     

小熊猫胃的解剖和组织结构研究

小熊猫的胃属单室腺型胃,它以角切迹为界,可分为胃底部和幽门部两部分。胃壁由粘膜、粘膜下层、肌层和浆膜四层组成。四上皮为单层柱状上皮,具有分泌粘液的功能。胃腺有贲门腺、胃底腺、幽门腺三种,但贲门腺不发达。主细胞、壁细胞和粘液细胞的数量与分布呈现规律性变化。肌层发达,特别是内环行肌发达。并与大熊猫胃的结构作了比较。     

Light,electron microscopical,and immunocytochemical investigation of the stomach wall of the tigerfish Hydrocynus forskahlii

The wall of the stomach of the tigerfish is described and compared with that of other vertebrates. Light microscopic and ultrastructural characteristics of the stomach wall correspond to a large extent to those of other vertebrates, although some differences are found. The mucosa contains (1) surface epithelium characterized by narrow columnar cells with abundant mucous granules; (2) gastric glands consisting of pepsinogenic cells of variable height, containing tubulovesicles and bearing microvilli; (3) five granulated cell types located basally in the epithelium (types 1–5); and (4) lamina propria and muscularis mucosae. Connective tissue separating smooth muscle fibers of the muscularis mucosae constitutes a stratum compactum. The submucosa contains a loose connective tissue, a tunica muscularis of inner circular and outer longitudinal layers, and a serosa of mesothelium and subjacent connective tissue. Immunocytochemical tests with antisera to five polypeptides show gastrin/cholecystokinin (CCK), vasoactive intestinal polypeptide (VIP) immunoreactivities in some cells of the gastric glands, and somatostatin in cells lying among epithelial cells lining the gastric luminal surface or gastric pits.     

日本沼虾消化道形态和组织学特点

应用石蜡切片和扫描电镜技术对日本沼虾消化道进行了研究。结果表明,食道壁向腔内形成四个纵突,食道上皮由单层柱状细胞构成,上皮下的结缔组织中具有放射肌和皮肤腺,环肌层近于连续。食道和胃连结处的管腔背方具食道瓣,胃内具胃磨、滤器和滤沟等结构,胃的组织学结构中除无皮肤腺分布外与食道相似。中肠较长,约占整个消化道的７１７％,具一对中肠前盲囊。中肠上皮细胞大致有两种类型,基膜着色深,环肌层连续,纵肌成束分散排列。后肠为一短管,管腔呈迷路状,其中部为一球形膨大的直肠。后肠的组织学结构与前肠相似。     

A morphological and histochemical analysis of the neuroendocrine system of the gut in Acipenser transmontanus

Morphological, histochemical and immunohistochemical data are presented to demonstrate that the enteric nervous system of the sturgeon is in part composed and arranged differently from other fish. It is composed of neurons which distribute both to the tunica propria-submucosa and tunica muscularis. Nerve cell bodies are small and nerve terminals run in bundles which are both unmyelinated and myelinated. The presence of myelinated nerve fibres in the enteric nervous system of vertebrates is infrequent. Ganglionated plexuses are only found in relation to the musculature. In contrast with the other tracts of the gut, the musculature of the oesophagus is arranged into two orthogonal layers, and the inner layer is composed of striated muscle fibres. Enzymes related to the classical neurotransmitters acetylcholine and adrenaline and some possible accessory neuromediators (CGRP-, somatostatin-, ANP-, substance P-, NPY-like peptides, and nitric oxide) were identified histochemically and immunohistochemically in components of the enteric nervous system, especially those which innervate the oesophagus. The diffuse endocrine system was limited to a gastric cell type, which synthesized a somatostatin-like peptide. Some of these special features of the enteric nervous system may possibly be related to functional properties peculiar to the sturgeon gut, which also shows aspects of morphological organization that are different to those of other fish.     

Pre-natal innervation of the human female genital tract

In the human fetus of 14 weeks, ganglia on either sides of the Müllerian uterovaginal canal contained two types of cells. In the 16th week, axons invaded the basal zone of the stratified squamous epithelium at the sides of the upper vagina. In the 20th week, vesicular nuclei typified the large neurons in the midportion of the cervico-vaginal ganglion. During the 22nd week, capsulated ganglia invaded the wall of the upper vagina forming three concentrically disposed strata. Non-capsulated clusters invaded its lamina propria. At the 24th week, axons were shaded after reaching the superficial zone of the stratified vaginal epithelium. In the 28th week, satellites surrounded the mature neurons and sheath cells enveloped the axons. Ganglia invaded the splitted muscle layer of the upper vagina at 30 weeks. Intraepithelial fibres invaded the whole thickness of the endometrium, the columnar epithelium of the cervix and uterine tube at 40 weeks. Nerve cells were detected among the basal epithelial cells of the lower vagina and its subepithelial plexus.     

Ultrastructural features of the gut in the white sturgeon, Acipenser transmontanus

Electron-microscopic examinations of the sturgeon gut were performed. Oesophageal goblet cells were abundant in the stratified epithelium. The ultrastructural features of the secretory granules of the oesophageal and intestinal goblet cells were quite similar to those of other vertebrates. Lobules of multilocular adipose tissue were observed in the deep tunica propriasubmucosa of the oesophagus, in close association with vasculature and large fibre bundles of myelinated and unmyelinated axons. Similarly composed nerve fibre bundles were observed in the cardiac stomach, too. The presence of myelinated axons is an unusual feature in the vertebrate enteric nervous system. Cardiac and fundic zones of the stomach showed an epithelium with columnar ciliated and non-ciliated cells, the latter equipped with fuzzy microvilli. Cells lining the tubular gastric proper glands were markedly granulated. Intestinal superficial epithelium was columnar and contained ciliated, as well as non-ciliated and goblet cells. In the tunica propria all over the intestine, the presence and ultrastructure of granulated cells was in addition described. Intraepithelial granulated leukocytes were seen throughout the alimentary canal. Various types of endocrine cells were seen both in the stomach and in the intestine, the size of their granules was measured and their ultrastructure described and compared to that of mammalian cell types.     

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。     

Immunolocalization of type IV collagen and laminin during rat gonadal morphogenesis and postnatal development of the testis and epididymis

Summary The distribution of type IV collagen and laminin was studied by immunocytochemistry during rat gonadal morphogenesis and postnatal development of the testis and epididymis. Immunostaining appeared as early as the 12th day of gestation along the basement membranes of the mesonephric-gonadal complex. The connection between some mesonephric tubules and coelomic epithelium was seen between the 12th and 13th day of gestation. Discontinuous immunostained basement membranes delineated the differentiating sexual cords in 13-day-old fetuses; this process probably began in the inner part of the gonadal ridge. The seminiferous cords surrounded by a continuous immunoreactive basement membrane are separated from the coelomic epithelium by the differentiating tunica albuginea in 14-day-old fetuses. During the postnatal maturation of epididymis and testis, the differentiation of peritubular cells is accompanied by a progressive organisation of the extracellular matrix into a continuous basement membrane. This change is associated with a gradual condensation of peritubular cells inducing an increase of immunostaining. In adult animals, the tubular wall of epididymis is thicker than the lamina propria of seminiferous tubules. Both type IV collagen and laminin immunostaining paralleled during ontogenesis at the light-microscope level.     

Immunolocalization of type IV collagen and laminin during rat gonadal morphogenesis and postnatal development of the testis and epididymis

The distribution of type IV collagen and laminin was studied by immunocytochemistry during rat gonadal morphogenesis and postnatal development of the testis and epididymis. Immunostaining appeared as early as the 12th day of gestation along the basement membranes of the mesonephric-gonadal complex. The connection between some mesonephric tubules and coelomic epithelium was seen between the 12th and 13th day of gestation. Discontinuous immunostained basement membranes delineated the differentiating sexual cords in 13-day-old fetuses; this process probably began in the inner part of the gonadal ridge. The seminiferous cords surrounded by a continuous immunoreactive basement membrane are separated from the coelomic epithelium by the differentiating tunica albuginea in 14-day-old fetuses. During the postnatal maturation of epididymis and testis, the differentiation of peritubular cells is accompanied by a progressive organisation of the extracellular matrix into a continuous basement membrane. This change is associated with a gradual condensation of peritubular cells inducing an increase of immunostaining. In adult animals, the tubular wall of epididymis is thicker than the lamina propria of seminiferous tubules. Both type IV collagen and laminin immunostaining paralleled during ontogenesis at the light-microscope level.     

Histological and histochemical observations on the forestomach of goat during pre-natal life.

Non-keratinized, stratified squamous epithelium lined the mucosa of the fore-stomach. The mucosal appendages in the form of ruminal papillae did not develop in the rumen during this study, however, omasal laminae and reticular ribs were evident in groups I and II, respectively. Cytoplasmic accumulations were evident in the middle layer of the epithelium, which is characteristic of this region. The thickness of the epithelium increased constantly in the rumen and reticulum, but in the omasum it remained constant with the increase in the size of the fetus. The corial papillae in the rumen, reticulum and omasum appeared at the 12.7-, 11.5-and 14.6-cm CVR stage, respectively. The muscularis mucosae appeared in the omasum at the 14.6-cm CVR stage in the first-order laminae. The tunica muscularis consisted of spirally arranged muscle fibre bundles. Cross-cut muscle fibre bundles below the tip of the omasal laminae descended downward with the increase in the size of the fetus and continued with the inner circular layer. Acid and alkaline phosphatases and fat could not be observed. The concentration of glycogen in the epithelium was maximum in group III and minimum in group II.