Ultrastructure of the colon of Locusta migratoria

The ultrastructure of the colon of Locusta migratoria is described. The colon is lined by a thick cuticle that, for the most part, adheres to the underlying epithelium. The cuboid epithelial cells are characterized by moderate invaginations of the apical and, to a lesser extent, basal plasma membranes; the lateral plasma membranes are relatively flat. The bulk of the mitochondria are located in the apical region of the cell and are not particularly associated with any of the plasma membranes. The basal region of the cells contains much rough endoplasmic reticulum, glycogenlike granules, and a predominance of spherical, electron-dense bodies of various sizes. Where muscle fibers make contact with the epithelium, the cells are much reduced; the cytoplasm is usually less electron-dense, and, typically, the nucleus has a thick layer of granular material associated with the inner nuclear membrane. The apical and basal plasma membranes of the reduced epithelial cells contain numerous hemidesmosomes. The apical hemidesmosomes occur in pairs around an extracellular space that contains electron-opaque material. The latter forms tonofibrillae that extend into the endocuticle. Bundles of microtubules are associated with the hemidesmosomes. The tubules traverse the cell from the apical to the basal region. The possible significance of these findings is discussed.     

Fine structure of the Malpighian tubules in the housefly, Musca domestica

The epithelium of the Malpighian tubules in the housefly is comprised of four distinct cellular types. Type I cells are characterized by the presence of intimate associations between infoldings of basal plasma membrane and mitochondria. On the luminal surface, cytoplasm is extended into microvilli which contain mitochondria. Membrane-bound vacuoles in the cytoplasm seem to progressively accumulate granular material. Type II cells have dilated canaliculi. Microvilli lack mitochondria. The Type III cell has not been reported previously in Malpighian tubules. It has very well-developed granular endoplasmic reticulum which contains intracisternal bundles of tubules. Cytoplasm contains numerous electron dense bodies. Type IV cells occur in the common duct region of the Malpighian tubules. Mitochondria do not extend into the microvilli.     

An ultrastructural and histochemical study of autoimmune aspermatogenesis in the rat testis

Summary Immune aspermatogenesis was induced in young rats by the method of Freundet al. (1954) and testes were studied by electron microscopic and histochemical methods. At time of sacrifice the testes of several animals were markedly atrophic as demonstrated by reduction in weight. Sections of seminiferous tubules exhibited primarily profiles of Sertoli cells but germinal elements were sparse or absent. The ultrastructure of Sertoli cells appeared to be normal except for the presence of areas of dilated smooth endoplasmic reticulum and fragments of phagocytized germ cells in the cytoplasm.Light microscopic sections showed an apparent hyperplasia of intertubular tissue. Electron micrographs revealed a moderate to extreme vesiculation of the smooth endoplasmic reticulum in many interstitial cells. Macrophages and lymphocytes were often observed in contact with these cells.There was increased localization of non-specific esterase and acid phosphatase associated with lipid bodies of the tubules and in intertubular areas.This work was supported in part by USPHS Grant FR 5391.     

Occurrence and Ultrastructure of Collar Cells in the Stomach Gastrodermis of Polypodium hydriforme Ussov (Cnidaria)

The existence of collar cells lining the stomach gastrodermis in free-living Polypodium hydriforme and their ultrastructure are described. The collar cells are provided with a collar consisting of 9–10 microvilli which encircles a central flagellum and forms a flagellar pit. At the bottom of the pit around the basal part of the flagellum there is fine crystalline material which extends also in the spaces between the microvilli and keeps them straight. The flagellum has a typical axoneme (9+2), its basal body is located below the apical surface of the collar cell and continues into a striated rootlet. An accessory centriole is situated close to the upper part of the rootlet. The cell nucleus is located in the basal part of the cell. Prominent mitochondria with tubular cristae, Golgi cisternae and fragments of rough endoplasmic reticulum are situated mostly in the basal part of the cytoplasm. Discoidal vesicles are abundant in the apical cytoplasm. The collar cells are connected to each other by septate junctions and interdigitations. The ultrastructure of collar cells described here is discussed in comparison to that of other Cnidarians and in connection with the problem of Polypodium's systematic position.     

Ultrastructure and function of follicle cell in the ovary of Branchiostoma belcheri

The ultrastructure of follicle cells in the ovary at different developmental stages ofBranchiostoma has been observed in detail with a transmission electron microscope. The results indicate that only one kind of follicle cell exists with structural features related to steroid hormone biosynthesis: (i) oval or round mitochondria with tubules; (ii) smooth surfaced endoplasmic reticulum; (iii) several large lipid droplets in the cytoplasm; (iv) a well developed Golgi complex and tubular rough surfaced endoplasmic reticulum, as can be found in mammalian theca interna cells. In addition, as steroid hormone synthesizing cells, they obviously play an important role in the phagocytosis of relict gametes and cellular debris and may have a nutritive function for the oocytes. They can produce abundant secretory granules in stages III-IV ovaries. In mature ovaries they transform into flat epithelial cells with numerous microfilaments which may play a role in ovulation.     

Fine structure of the dorsal epithelium of the tongue of the freshwater turtle,Geoclemys reevesii (Chelonia,Emydinae)

Scanning electron microscopy shows that lingual papillae occur all over the dorsal surface of the tongue of the freshwater turtle, Geoclemys reevesii. The surface of each papilla is composed of compactly distributed hemispherical bulges, each composed of a single cell. Microvilli are widely distributed over the surface of cells. Histological examination reveals that the connective tissue penetrates deep into the center of papillae and that the epithelium is stratified columnar. Under the transmission electron microscope, the cells of the basal and the deep intermediate layers of the epithelium appear rounded. A large nucleus lies in the central area of each cell. The cytoplasm contains mitochondria, endoplasmic reticulum and free ribosomes. The cell membrane form numerous processes. The shallow intermediate layer contains two types of cell. The cytoplasm of the first has numerous fine granules, in addition to mitochondria, ribosomes, and endoplasmic reticulum. The other type of cell contains highly electron-dense granules. The surface layer shows two cell types. One type consists of typical mucous cells. The other type of cell contains fine, electron-lucent granules. The latter cells lie on the free-surface side, covering the mucous cells, and have microvilli on their free surfaces.     

Asymmetry in the cytoplasm of oocytes of largescale yellowfish Labeobarbus marequensis Smith 1841 (Teleostei: Cypriniformes: Cyprinidae)

The ovaries of the largescale yellowfish, Labeobarbus marequensis (Teleostei: Cypriniformes: Cyprinidae), are made up of the germinal epithelium, nests of late chromatin nucleolus stage oocytes, and ovarian follicles. Each follicle is composed of a single oocyte, which is surrounded by somatic follicular cells and a basal lamina covered by thecal cells. We describe polarization and ultrastructure of oocytes during the primary growth stage. The oocyte nucleus contains lampbrush chromosomes, nuclear bodies and fibrillar material in which multiple nucleoli arise. Nuage aggregations composed of material of a nuclear origin are present in the perinuclear cytoplasm. The Balbiani body (Bb) contains aggregations of nuage, rough endoplasmic reticulum, individual mitochondria and complexes of mitochondria with nuage (cement). Some mitochondria in the Bb come into close contact with endoplasmic reticulum cisternae and vesicles that contain granular material. At the start of primary growth, the Bb is present in the cytoplasm close to the nucleus. Next, it expands towards the oocyte plasma membrane. In these oocytes, a spherical structure, the so-called yolk nucleus, arises in the Bb. It consists of granular nuage in which mitochondria and vesicles containing granular material are immersed. Later, the Bb becomes fragmented and a fully grown yolk nucleus is present in the vegetal region. It contains numerous threads composed of granular nuage, mitochondria, lysosome-like organelles and autophagosomes. We discuss the formation of autophagosomes in the cytoplasm of primary growth oocytes. During the final step of primary growth, the cortical alveoli arise in the cytoplasm and are distributed evenly. The eggshell is deposited on the external surface of the oocyte plasma membrane and is made up of two egg envelopes that are pierced by numerous pore canals. The external egg envelope is covered in protuberances. During primary growth no lipid droplets are synthesized or stored in the oocytes.     

Previtellogenic oocytes of South African largemouth bass Micropterus salmoides Lacépède 1802 (Actinopterygii,Perciformes) - the Balbiani body,cortical alveoli and developing eggshell

The ovaries of the largemouth bass Micropterus salmoides, an alien and invasive species in South Africa, contain a germinal epithelium which consists of germline and somatic cells, as well as previtellogenic and late vitellogenic ovarian follicles. The ovarian follicle consists of an oocyte surrounded by follicular cells and a basal lamina; thecal cells adjacent to this lamina are covered by an extracellular matrix. In this article, we describe the Balbiani body and the polarization and ultrastructure of the cytoplasm (ooplasm) in previtellogenic oocytes. The nucleoplasm in all examined oocytes contains lampbrush chromosomes, nuclear bodies and several nucleoli near the nuclear envelope. The ultrastructure of the nucleoli is described. Numerous nuage aggregations are present in the perinuclear cytoplasm in germline cells as well as in the ooplasm. Possible roles of these aggregations are discussed. The ooplasm contains the Balbiani body, which defines the future vegetal region in early previtellogenic oocytes. It is comprised of nuage aggregations, rough endoplasmic reticulum, Golgi apparatus, mitochondria, complexes of mitochondria with nuage-like material, and lysosome-like organelles. In mid-previtellogenic oocytes, the Balbiani body surrounds the nucleus and later disperses in the ooplasm. The lysosome-like organelles fuse and transform into vesicles containing material which is highly electron dense. As a result of the fusion of the vesicles of Golgi and rough endoplasmic reticulum, the cortical alveoli arise and distribute uniformly throughout the ooplasm of late previtellogenic oocytes. During this stage, the deposition of the eggshell (zona radiata) begins. The eggshell is penetrated by canals containing microvilli and consists of the following: the internal and the external egg envelope. In the external envelope three sublayers can be distinguished.     

Ultrastructural determination of gingival Langerhans cells in alloxan-induced diabetic rats

The ultrastructure of Langerhans cells has not been fully investigated in diabetes-associated gingival tissues. The present study was carried out to investigate the ultrastructure of gingival Langerhans cells in alloxan-induced diabetic rats. Gingival biopsies were obtained from 22 diabetic and 18 control rats. Langerhans cells were observed by transmission electron microscopy (TEM) in the basal layers of healthy oral epithelium. On rare occasions, Langerhans cells were found in the suprabasal layers of the oral epithelium. Langerhans cells in the oral epithelium of diabetic rats were seen in the basal and suprabasal layers. Usually, Langerhans cells had clear cytoplasm and convoluted or indented nuclei and few or no specific granules. The clear cytoplasm contained mitochondria, lysosomes and a small number of rough-surfaced endoplasmic reticulum regions, but it lacked tonofilament. Occasionally, centrioles were also observed in the cytoplasm. The membrane of Langerhans cells had no junctional complexes such as desmosomes. In diabetic rats, Langerhans cell precursors were developed into specific granule-bearing cells. Both Langerhans cells and their granules were more frequent in the gingiva of diabetic rats than in the control group. These data suggest that Langerhans cells play an important role in explaining the pathogenesis and development of diabetic gingivitis.     

Occurrence of unusual heterogeneous lipid-containing granule-storing cells in the main excretory duct epithelium of the male mouse submandibular gland

Summary The fine structure of the main excretory duct epithelium of the male mouse submandibular glands was investigated by scanning and transmission electron microscopy. Three principal cell-types were observed: type I and II, and basal cells. This epithelium was characterized by the presence of intercellular canaliculi. Type-I cells were the most numerous. They had an abundance of mitochondria, well-developed Golgi apparatus, a few electron-lucent lipid-containing granules and poorly developed basal infoldings. These cells were also characterized by many glycogen granules throughout the cytoplasm and abundant smooth endoplasmic reticulum in the apical cytoplasm. Type-II cells were the second most numerous. Their most characteristic feature was the presence of abundant heterogeneous lipid-containing granules having acid phosphatase activity at the periphery. They were concentrated in the infra- and supranuclear cytoplasm. The granules may be derived from mitochondrial transformation and seem to be a special kind of secondary autolysosome. Type-II cells also contained abundant mitochondria throughout the cytoplasm, much smooth endoplasmic reticulum in the apical cytoplasm, a well developed Golgi apparatus adjacent to the heterogeneous lipid-containing granules and no basal infoldings. Basal cells were situated adjacent to the basal lamina. They had a large nucleus and the cytoplasm was filled with glycogen granules.     

The ultrastructure of malpighian tubules and the chemical composition of the cocoon of Aeolothrips intermedius Bagnall (Thysanoptera)

The secretory activity of the two branched malpighian tubules (MTs) of the second‐instar larva in Aeolothrips intermedius is described. MTs of adult thrips have the typical ultrastructure of excretory epithelium with apical microvilli containing long mitochondria and a rich system of basal membrane infoldings. In the second‐instar larva just before pupation, the ultrastructure of MT epithelial cells is dramatically different, and there are numerous huge Golgi systems in the cytoplasm. These cells are involved in an intense secretory activity to produce an electron‐dense product which is released into the MTs lumen. This secretion is extruded from the hindgut and used by the second‐instar larva to build an elaborate protective cocoon for pupation. Electron‐spray‐ionization mass spectrometry analysis of the cocoon revealed the presence of a β‐N‐acetyl‐glucosamine, the main component of chitin, which is also present in the cocoons of Neuroptera and some Coleoptera. J. Morphol., 2010. © 2009 Wiley‐Liss, Inc.     

Structural and ultrastructural features of boar seminal vesicles

The morphological features of boar seminal vesicles were examined by light and transmission microscopy. Boar seminal vesicles consist of glandular tissue arranged in multiple lobules containing a system of ramified secretory tubules. The secretory tubules are composed of a mucosa formed by an epithelium and an underlying lamina propria and, are surrounded by a muscular layer. The epithelium is made up of columnar cells and occasional basal cells. Mast cells are frequently found among epithelial cells. Three types of columnar cells, considered different stages of the secretory cell cycle, are present: principal cells, clear cells and dense cells. Principal cells are functionally differentiated cells characterised by abundant mitochondria, great development of the rough endoplasmic reticulum and presence of secretory granules in their cytoplasm. The apical surface of many principal cells shows apical blebs filled with PAS-positive material. No acid mucosubstances are detected. Microvilli cover the apical surface except in the apical blebs. Dense cells, arranged between principal cells, are also functional differentiated cells but with signs of cellular degeneration. Clear cells are an initial differentiated stage of columnar cells and are characterised by the presence of a poorly developed rough endoplasmic reticulum and by the absence of secretory granules. Proliferating cells are present among columnar cells. Basal cells contain scarce cytoplasm, few organelles and no secretory granules. The lack of mitotic activity in these cells suggests that they do not act as precursors of columnar cells.     

Ultrastructural, histochemical and cytochemical characterization of intestinal epithelial cells in Aplysia depilans (Gastropoda, Opisthobranchia)

To improve the current knowledge about the digestive system in opisthobranchs, light and electron microscopy methods were used to characterize the epithelial cells in the mid‐intestine of Aplysia depilans. This epithelium is mainly formed by columnar cells intermingled with two types of secretory cells, named mucous cells and granular cells. Columnar cells bear microvilli on their apical surface and most of them are ciliated. Mitochondria, multivesicular bodies, lysosomes and lipid droplets are the main components of the cytoplasm in the region above the nucleus of these cells. Peroxisomes are mainly found in middle and basal regions, usually close to mitochondria. Mucous cells are filled with large secretory vesicles containing thin electron‐dense filaments surrounded by electron‐lucent material in which acidic mucopolysaccharides were detected. The basal region includes the nucleus, several Golgi stacks and many dilated rough endoplasmic reticulum cisternae containing tubular structures. The granular cells are characterized by very high amounts of flat rough endoplasmic reticulum cisternae and electron‐dense spherical secretory granules containing glycoproteins. Enteroendocrine cells containing small electron‐dense granules are occasionally present in the basal region of the epithelium. Intraepithelial nerve fibres are abundant and seem to establish contacts with secretory and enteroendocrine cells.     

Intracellular Transport and Elimination of Resin from Epithelial Duct-cells of Pinus halepensis

The ultrastructure of the resin secreting cells of root ductsof young Pinus halepensis seedlings was studied. It is suggestedthat the endoplasmic reticulum (ER) in addition to taking partin resin synthesis also plays a role in transporting the resinfrom the plastids, mitochondria and nuclear envelope to theplasmalemma. By fusing with the plasmalemma the ER releasesthe resin to the outside of the protoplast. The resin producedin the ground cytoplasm and by the Golgi apparatus seems tobe eliminated by plasmalemma invaginations. Pinus halepensis, resin secretion, root ducts, endoplasmic reticulum     

Ultrastructure of the sternal glands inThrips validus uzel (Thysanoptera,terebrantia)

Summary The ultrastructure of the sternal glands of the males ofThrips validus is consistent with the hypothesis that they are involved in pheromone production. The secretory cells, which are strongly modified epidermal cells, are characterized by the abundance of mitochondria and the presence of agranular, tubular endoplasmic reticulum (ATER) and microbodies. Each of the numerous apical microvilli encloses one or several tubular extensions of ATER. Some mitochondria are in close contact with ATER tubules. The mitochondrial matrix is probably involved in the elaboration of the secretory product, which is extruded and possibly modified by the agranular reticulum. The secretion is sudanophilic, but not osmiophilic. No lipid droplets are found in the cytoplasm. After storage in the strongly dilated subcuticular space, the secretion is released by epicuticular ductules with a diameter of about 120 å.I should like to thank the staff of the EM laboratory of the Zoological Institute for technical assistance, especially the photographer, Mrs. M. Ullmann     

Ultrastructural investigations of Arbutus unedo-Laccaria amethystea mycorrhiza synthesized in vitro

Summary Anatomy and ultrastructure of the arbutoid mycorrhiza of Arbutus unedo-Laccaria amethystea from axenic culture are described. In comparison to non-inoculated roots, the rhizodermal cells of mycorrhizas are of greater volume, their nuclei are enlarged and show an irregular shape, plasmalemma and cytoplasm with mitochondria, plastids, endoplasmic reticulum and dictyosomes are increased. Several ontogenetical states are documented. The arbutoid mycorrhiza as a connecting link between ectomycorrhiza and ericoid mycorrhiza is discussed.     

Aspects of sieve element ultrastructure in Primula obconica

Summary At maturity, the enucleate sieve element of Primula obconica is lined with a parietal layer of cytoplasm consisting of plasmalemma, one or more cisterna-like layers of endoplasmic reticulum, numerous mitochondria and plastids, and a membrane which apparently separates these cytoplasmic components from a large central cavity. The central cavity contains numerous longitudinally oriented slime tubules. We believe these tubules normally form strands which run the length of the cell and traverse consecutive cells through the sieve-plate pores. Developmental aspects are discussed.This research has been supported by NSF Grant GB 3193.     

甜菜夜蛾微孢子虫研究:Ⅲ.超微结构与致病机理

从甜菜夜蛾幼虫体内首次分离到一种侵染寄主脂肪体、马氏管和中肠的微孢子虫,该微孢子虫对甜菜夜蛾、菜青虫和棉铃虫幼虫有较强的致病力,并可经卵垂直传播;水平传播主要借助于病虫的粪便及虫尸。用电镜观察了该微孢子虫感染甜菜夜蛾幼虫后的超微结构变化。结果表明：寄主细胞被感染后,细胞核膨大并变形,由正常的圆球形被挤压成长条状,但核膜及核周间隙没有发生变化;线粒体体积变小,嵴增宽,嵴的排列方向发生改变,双层膜部分     

取食转Bt基因水稻对稻纵卷叶螟幼虫中肠的组织病理学效应

利用透射电镜观察了稻纵卷叶螟 Cnaphalocrocis medinalis（Guenée）幼虫取食转Bt基因水稻后中肠的组织病理变化。结果表明：稻纵卷叶螟幼虫取食转cry1Ab基因水稻后,中肠上皮细胞的线粒体先发生形态变化,随连续取食时间的延长线粒体出现凝聚、内嵴稀疏、空泡化等,在后期还呈凝聚态随突起脱落或沿杯腔边沿单一排列。内质网的变化也很明显,病变过程中伴随着粗糙内质网的肿胀、核糖体脱落,粗糙内质网增多等现象。细胞核的变化较小,在处理后期出现细胞核拉长、核仁聚集等变化。组织病变程度不一,有的细胞在病变早期就出现了空泡化。     

Observations on the gametolytic gland in the anaspidean opisthobranchs,Phyllaplysia taylori and Aplysia californica

The wall of the gametolytic gland in Aplysia and Phyllaplysia consists of a muscular layer lined with an epithelium incorporating four distinct cell types, some of which show intense secretory activity. The cytoplasm of these cells, rich in RNA, has a peripheral layer of densely-packed mitochondria in association with a smooth endoplasmic reticulum. Lipid globules, perhaps resulting from absorption of lumen contents by microvilli, appear in the cytoplasm in the course of growth and reproductive activity. A basal band of fibrillar material appears to serve as a cytoplasmic skeleton. The elaboration of cell types, extensive areas of cytoplasmic RNA, and vigorous secretory activity suggest important roles for this organ such as development of food reserves, recycling of sexual materials of high physiological value, and interaction with the bag cells of the nervous system in coordinating ovulation with the availability of capacitated, exogenous sperm.