Schistosoma mansoni: ultrastructure of cercarial escape glands

While in the sporocyst, the cercaria of Schistosoma mansoni has a pair of unicellular escape glands whose funduses are located together on one side of the body. The funduses taper into microtubule lined ducts that open on the anterior surface of the oral sucker through desmosome supported pores in the immediate vicinity of the ducts of the acetabular glands. The glands contain membrane-bound secretory granules which have a fine medium-dense, homogeneously granular material in their matrices. A large membrane-bound reservoir of granular material, whose texture is similar to that of the secretory granules, is often seen in the cytoplasm of the funduses. In free-swimming cercariae, the ducts in the oral sucker are the only obvious remains of the escape gland.     

Schistosoma mansoni: histochemical analysis of the postacetabular gland secretion of cercariae

Contents of the funduses and ducts of the postacetabular glands of Schistosoma mansoni cercariae, the secreted deposits, and the surface film were compared by their histochemical reactions. Techniques for carbohydrate-containing substances, neutral and acid mucosubstance, proteins and amino acids, and enzymes were used. The secretion reacted differently before (within the glands) and after (in secreted deposits) emission.Before emission, the postacetabular gland contents reacted as a neutral mucosubstance containing periodate-engendered and periodate-reactive aldehydes rich in vic-glycols or their substituted amines, probably hexoses other than glucose, such as fucose or galactose. No reactions of significance were observed for acid groups or for glycogen or lipids. In this state, the secretion is termed mucigen.After emission, the secretion stained not only as mucigen, but also as acid mucosubstance, apparently sialomucin. After emission, it is termed mucin.It is probable that acid radicals were present in mucigen but were masked stearically by the presence of adjacent neutral radicals or basic proteins. The surface film reacted as both a neutral and an acid mucosubstance. Evidence suggested that the film itself was neutral and that the reaction for acid mucosubstance was from an overlay of mucin secreted from the postacetabular glands.Proteins and amino acids, especially arginine, and some tyrosine and tryptophan were indicated in mucigen and in mucin by the histochemical tests. There was no histochemical evidence of enzymes. Secretion of the postacetabular glands is concluded from histochemical reactions, as from earlier chromatographic data (Stirewalt and Evans 1960), to be a carbohydrate-protein-lipid complex.     

日本血吸虫尾蚴发育的超微结构观察：Ⅱ.腺体

在透射电镜下观察不同发育期日本血吸虫尾蚴的腺体。结果：胚球期（Ｓ２）主要出现体细胞分裂与分化,首次证明分泌细胞及其小体在Ｓ２出现,雏体期（Ｓ３）见到前钻腺细胞体与钻腺管束及分泌小体。成熟前期（Ｓ４）钻腺分泌小体基质分Ａ／Ｂ为主两型,分别演变为成熟期（Ｓ）５的后／前钻腺分泌小体。头腺分泌小体亦在Ｓ４出现。从前钻腺体排至头器远端腺管的分泌小体,显眼透明球消失成为致密同质性小体,已为大家共识。而在后钻腺     

日本血吸虫尾蚴头器、腺体及体被超微结构的观察

本文报告用扫描与透射电镜观察大陆品系日本血吸虫(Schistosoma japonicum)尾蚴的头器、膆体及体被的超微结构。 从不同角度扫描电镜观察日本血吸虫的尾蚴头器前端,见有5对钻腺的开口,开口的周围有围褶,围褶的外侧分布有7对无鞘单纤毛的感觉乳突,这些结构靠近头器的腹侧围成马蹄形,顶端为无棘区。作者综合有关图像重建日本血吸虫尾蚴头器表面结构的示意图,供参考。 日本血吸虫尾蚴的体被、头腺及钻腺与曼氏血吸虫尾蚴基本相似,但在前钻腺分泌小体我们另见有连续性条索状透明物,对它的形成及其性质进行了讨论。     

Schistosoma mansoni: Development of acetabular glands of cercaria at ultrastructural level

Cercariae of Schistosoma mansoni in daughter sporocysts in Biomphalaria glabrata were studied with the electron microscope to observe the maturing process of their acetabular glands. The undifferentiated acetabular gland displays its enlarged basal area (fundus) and extended narrow process (duct) before other organ systems are recognized. Its fundus contains a prominent nucleus and subcellular organelles typical of active secretory cells.The secretory granules of the postacetabular glands are formed in a milieu of dilated rough endoplasmic reticulum and Golgi. Two morphologically different secretory granules are produced: (1) homogeneously granular ones, and (2) other granular ones with electron dense bodies in their matrices. Mostly, the homogeneously granular ones are produced first in the fundus and are forced into the ducts as the other type is formed.The secretory granules of preacetabular glands are formed from translucent vacuoles which arise from an environment of endoplasmic reticulum and Golgi. Two morphologically different secretory granules are produced: (1) one type has a homogeneous dense matrix, and (2) the other type has a less dense matrix containing electron-lucid bodies.The duct of an undifferentiated acetabular gland has either filamentous material or microtubules dispersed in its cytoplasm. Once microtubules are formed, they persist during the life of the cercaria. The microtubules are believed to have possibly two functions: (1) to support the long duct, and (2) to assist the movement of the secretory granules into the channels of the ducts where they remain until released during host penetration.Few of the subcellular organelles associated with secretory granules formation are seen in the duct except the area in close proximity to the fundus; thus, the few secretory granules produced in the duct are in this region.     

Structural and ultrastructural features of boar bulbourethral glands

The morphological features of boar bulbourethral glands were examined by light and transmission microscopy. Bulbourethral glands are compound tubuloalveolar glands surrounded by a capsule of dense connective tissue and arranged in multiple lobules formed by endpieces and excretory ducts. Endpieces and excretory ducts are both lined by a single epithelium of mucous cells with a basal nucleus. Epithelial cells accumulate secretory granules containing neutral and carboxylated acid mucosubstances and a small amount of sulphated acid mucosubstances. The ultrastructure of epithelial cells varies according to the secretory cycle. In initial stages, the cells show a columnar shape and secretory granules unevenly distributed in the cytoplasm. As the synthesis of mucosubstances progresses, the amount of the secretory granules increases and the cellular shape becomes pyramidal. Secretory granules can contain inclusions and present differences among them according to their different phases of formation. In pyramidal cells, secretory products are released into the lumen by a merocrine mechanism.     

日本血吸虫尾蚴人工方法转变的童虫超微结构的观察

本文报道日本血吸虫尾蚴经注射器推压和血清孵育两种人工方法转变的童虫与载体皮肤型童虫的透射及扫描电镜的观察结果。描述了三种童虫在转变后3小时至12小时其糖膜、外质膜、体被内包含体及腺体的超微结构的变化。     

The development of the sweat and sebaceous glands in the skin of the one-humped camel (Camelus dromedarius)

The sweat gland primordium appeared as a solid bud from the ental side of the epithelial cords of the growing hair follicles in the CRL 36 cm-fetus from the primary hair follicles and in the CRL 64 cm-fetus from the secondary ones. In the CRL 68 cm-fetus the glands were tubular with a slight curving of their lower third, which became convoluted at the CRL 83 cm-stage. At the latter age, clear myoepithelial cells were observed in the secretory portion as also in the duct. The buds of the sebaceous glands could be observed in the CRL 45 cm-fetus from the primary hair follicles and in the CRL 68 cm-fetus from the secondary ones. At the CRL 83 cm-fetal stage, the branched glands were elongated in shape and opened into the follicles by two separated ducts, united at the hair canal. The glands were in function nearly from its early development.     

Schistosoma mansoni: description of the head gland of cercariae and schistosomules at the ultrastructural level.

The head gland of the cercaria of Schistosoma mansoni appears to be a relatively large unicellular entity consisting of a fundus tapering into a system of multiple ducts that opens into the integument at the anterior end of the oral sucker. The fundus is located in the posteriodorsal area of the oral sucker and contains most of the secretory granules. The ducts are usually narrow and devoid of secretory granules especially near their integumental junctions in the cercaria. In Schistosomules of S. mansoni the fundus is reduced and the ducts are distended as secretory granules move en masse into the integument during the penetration of cercaria into their host where they may provide material for repair of the integument of the oral sucker damaged during penetration. The head gland has a strong affinity for luxol fast blue and acid hematin stains which suggests the presence of phospholipids.     

Occurrence and morphometry of the hypopharyngeal glands inScaptotrigona postica Lat. (Hymenoptera, Apidae, Meliponinae)

As compared toApis mellifera where only workers have hypopharyngeal glands, inScaptotrigona postica, these glands occur in workers, queens and males. They are composed of two long axial ducts with many unicellular secretory alveoli interconnected by secretory canaliculi. The axial ducts are longer in males than in workers, but the alveolar areas of queens and males are generally smaller. In workers the alveoli have their greatest size in the nurses or middle-aged individuals while in queens and males they are larger in newly emerged individuals. The results indicate that the glands in workers may produce food for the brood as inA. mellifera, since they are well developed in the nurse workers. However, the function of the glands in queens and males remains to be clarified since these individuals have no part in brood care.     

The post-embryonic changes in Melipona quadrifasciata anthidioides Lep. (Hym. Apoidea). II. Development of the salivary glands system

The paper deals with the development of the salivary gland system in Melipona quadrifasciata anthidioides, which begins in the prepupal stage. The silk glands degenerate by autolysis at the end of the larval stage. Degeneration is characterized by cytoplasmic vacuolization and pycnosis of the nuclei of the secretory cells. The glandular secretory portion of degenerated silk glands separates from the excretory ducts. The salivary glands develop from the duct of the larval silk glands. The thoracic salivary glands develop from the ducts of the secretory tubules and the head salivary glands from the terminal excretory duct. The mandibular glands appear in the prepupa as invaginations of mandibular segments, and their differentiation to attain the adult configuration occurs during pupation. The hypopharyngeal glands have their origin from evaginations of the ventral anterior portion of the pharynx. A long tubule first appears with walls formed by more than one cellular layer. Then some cells separate from the lumen of the duct, staying attached to it by a cuticular channel in part intracellular. The initial duct constitutes the axial duct, in which the channel of the secretory cells opens. During the development of salivary and mandibular glands, they recapitulate primitive stages of the phylogeny of the bees. During the development of salivary glands system, mitosis accounts for only part of the growth. Most of the growth occurs by increase in size of cells rather than by cell division. In brown-eyed and pigmented pupae six days before emergence, the salivary gland system is completely developed, although not yet functioning.     

Ultrastructural observations on mehlis' gland in the monogeneans, Diplozoon paradoxum and Calicotyle kröyeri

Mehlis' gland of both Diplozoon paradoxum and Calicotyle kröyeri is composed of two cell types that taper to form ducts opening into the lumen of the ootype. The cells are invested with fibrous interstitial material and form a close structural relationship with surrounding parenchyma. The most prevalent cell type, the S₁ cell, is characterized by an extensive GER with narrow cisternae containing a finely granular material, and numerous Golgi stacks involved in the formation of multi-vesicular secretory bodies. In the S₂ cells the GER cisternae are greatly distended with a finely filamentous material and the Golgi give rise to dense secretory bodies with a packed fibrous appearance. There are species differences in the fine structure of the secretory bodies and these may reflect differences in the chemical composition of the glands. The ducts of the glands are lined with microtubules and are anchored to the ootype epithelium by septate desmosomes. They convey the secretory products to the ootype where they are released, apparently by exocytosis involving membrane fusion, into the lumen. The ootype is lined by a highly folded cellular epithelium which in D. paradoxum is ciliated. The cells contain profiles of GER and Golgi complexes and produce a third type of secretion which is also discharged into the ootype lumen.     

Structure of the male reproductive accessory glands of Pterostichus nigrita (Coleoptera: Carabidae), their role in spermatophore formation

Accessory gland secretions of male insects have many important functions including the formation of spermatophores. We used light and electron microscopy to investigate the structure of the accessory glands and posterior vasa deferentia of the carabid beetle Pterostichus nigrita to try to determine where spermatophore material is produced. Each accessory gland and posterior vas deferens had an outer layer of longitudinal muscle, beneath which was a layer of connective tissue and a thin band of circular muscle, all of which surrounded a layer of epithelial cells lining the lumen of the ducts. Based on the ultrastructure of the epithelial cells, and their secretory products, we identified two epithelial cell types in each region (distal and proximal) of the accessory glands and four types in the posterior vas deferens. Most secretory products, which stained positively for proteins and some mucins, were released into the lumen of the ducts by apocrine secretion. The accessory glands produced one type of secretory product whereas in posterior vasa deferentia, four types of secretory products were found layered in the lumen. Our results suggest that most of the structural material used to construct a spermatophore is produced by the cells of the posterior vasa deferentia.     

Morphology and ultrastructure of the abdominal integumentary glands of Acanthoscelides obtectus Say (Coleoptera : Bruchidae)

The morphology of the abdominal integumentary glands of the bean weevil Acanthoscelides obtectus (Coleoptera : Bruchidae) is described. There are 2 types: glands with long secretory ducts and ampullate glands with short ducts. The former are distributed throughout the integument and have 2 secretory cells, one of which is connected to the reservoir in the distal receptor zone, and the other to the duct. The duct, which is 100 μm long, has an epicuticular structure and its evacuation pore is 0.5 μm in diameter. It is surrounded by cytoplasm rich in microtubules. The epicuticular structure of the duct is resolved into fine filaments in the distal region. The ampullate glands exist only on the abdominal tergites and the pygidium. They are composed of an epicuticular receptor ampoule and a short duct connected to one secretory cell. The 2 types of glands can be placed in class 3 according to the nomenclature of Noirot and Quennedey (1974. Annu. Rev. Entomol. 19: 61–80).     

Schistosoma mansoni: localization of calcium-detecting reagents in electron-lucent areas of specific preacetabular gland granules

In an attempt to establish the exact location of calcium within the preacetabular glands of cercariae of Schistosoma mansoni, these larvae were exposed to reagents (potassium oxalate, potassium pyroantimonate, chloranilic acid, and silver nitrate) useful in the detection of calcium, and were subsequently observed with the aid of light and electron microscopes. Cercariae incubated in potassium oxalate and viewed in polarized light showed birefringence only in the preacetabular gland funduses. At the ultrastructural level, the preacetabular glands of potassium oxalate-treated cercariae had no electron-dense precipitate, but instead had translucent, irregularly shaped inclusions, similar to spaces left by volatilized calcium oxalate as described by others. Pyroantimonate treatment, on the other hand, localized the reaction in the electron-lucent areas of the light-spotted granules. The von Kossa silver nitrate procedure destroyed the secretory granules; therefore, an electron-dense precipitate was distributed throughout the gland. However, pretreatment with chloranilic acid before fixation preserved the granules, and subsequent exposure to the von Kossa silver nitrate gave a reaction identical to that obtained with the pyroantimonate alone. When viewed in polarized light, chloranilic acid-incubated cercariae showed birefringence in the fundus and duct areas.     

Histology and histochemistry of the accessory reproductive glands in the male hairy-nosed wombat (Lasiorhinus latifrons)

Summary The accessory male reproductive glands of the hairy-nosed wombat, Lasiorhinus latifrons, are a prostate and three pairs of Cowper's glands. Component units of all are branched tubular structures of varying epithelial makeup and secretory content. The prostate has the carrotlike shape and three consecutive regions commonly found in marsupials. The regions differ in their tubular histology and histochemistry: all contain secretory globules in glandular lumina. Cowper's glands A and B are histologically identical except for the absence of interstitial mast cells from gland B: gland C is characterized by narrower tubules and larger epithelial cells. Histochemical tests for protein, carbohydrate and iron indicate that glycogen is a major secretory product of the prostate (largely posterior region), iron is also secreted (mainly posterior region) and a small quantity of acid mucin is produced (mainly central region). Glycogen is a feature also of anterior prostatic glandular epithelium and of the capping cells of the urethral transitional epithelium. Cowper's gland A has considerable protein in its secretion, gland B a neutral glycoprotein and gland C a sialomucin: the latter two also exhibit cytoplasmic glycogen in their secretory cells.     

A comparative ultrastructural study of in vivo and in vitro derived adults of Microphallus similis

Davtes C. 1980. A comparative ultrastructural study of in vivo and in vitro derived adults of Microphallus similis. International Journal for Parasitology10: 217–266. The ultrastructure of in vitro cultured adults of Microphallus similis was examined by TEM and SEM and compared to that of metacercariae and in vivo grown adults. In cultured flukes the most conspicuous abnormalities were observed in secretory cells, especially those of the tegument, digestive caecum, forebody glands and vitellaria. In the tegumental cells and the forebody gland cells, the secretory granules appeared to lose some of their contents within the cell bodies suggesting that there may be some defect in the transport and/or packaging of secretory granules in vitro. In the vitellaria of cultured flukes some of the granules lost their characteristic appearance, becoming ragged in outline and very electrondense. The premature tanning of the vitelline secretions within the vitellaria is correlated with abnormal egg production in vitro. The caecal cells of cultured flukes differed from those of the metacercaria and the normal adult in several important respects which suggested that their function was probably impaired.     

Anatomical studies of the secretory structures: Glandular trichomes and ducts, in Grindelia pulchella Dunal (Astereae, Asteraceae)

The ultrastructure of the glandular trichomes and secretory ducts of Grindelia pulchella was studied. Plastids, mitochondria and endoplasmic reticulum are involved in the secretory process of both, trichomes and ducts. A special tissue with “transfer cells” is associated with the duct epithelial cells. The secretion is produced in the transfer cells and then is transferred to the duct epithelial cells where it accumulates in the vacuoles. The occurrence of cavities within the cell walls of the trichome cells and duct epithelial cells is described. The secretion is accumulated between the cell wall and the cuticle of these cells. When the cuticle is broken the secretion is released. We conclude that granulocrine secretion operates in this species.     

Monoclonal Antibodies to the Esophageal Glands and Stylet Secretions of Heterodera glycines

Three monodonal antibodies (MAbs) that bound to secretory granules within the subventral esophageal glands of second-stage juveniles (J2) of the soybean cyst nematode (SCN), Heterodera glycines, were developed from intrasplenic immunizations of a mouse with homogenates of SCN J2. Two MAbs to the secretory granules within subventral glands and one MAb to granules within the dorsal esophageal gland of SCN J2 were developed by intrasplenic immunizations with J2 stylet secretions. Stylet secretions, produced in vitro by incubating SCN J2 in 5-methoxy DMT oxalate, were solubilized with a high pH buffer and concentrated for use as antigen. Three of the five MAbs specific to the subventral esophageal glands bound to stylet secretions from SCN J2 in immunofluorescence and ELISA assays. Two of these three MAbs also bound to secretory granules within both the dorsal and subventral esophageal glands of young SCN females. All five of the subventral gland MAbs bound to the subventral glands of Heterodera schachtii and one bound to the subventral glands of Globodera tabacum, but none bound to any structures in Meloidogyne incognita or Caenorhabditis elegans.