Immunoelectron microscopical demonstration of endogenous avidin in secretory granules of the hen oviduct mucosa: a preliminary study

Summary The localization of avidin in the oviduct of the laying hen was investigated using ultrastructural immunoperoxidase techniques. Endogenous avidin was localized in secretory granules of both tubular gland cells and non-ciliated single epithelial cells in the magnum mucosa. These immunospecific granules were electron-dense and heterogeneous with a patchy core and dense peripheral region, especially in acinar cells. The size varied from small to large in the gland cells (500–2200 nm in diameter) and remained small in the epithelial cells (180–720 nm). Columnar epithelial cells containing avidin granules strongly resembled the protodifferentiated tubular gland cells appearing in the magnum mucosa of chicks artificially pretreated with ovarian hormones. On the other hand, no avidin was observed in either epithelial goblet cells or ciliated cells in adult hens, although both cell types were shown to produce avidin in young chicks when synchronized by the administration of progesterone. The present results parallel those obtained with biotinylated enzyme affinity methods in our previous cytochemical study.Therefore, avidin is one of the proteins produced and stored in the secretory granules of the tubular gland cells and protodifferentiated acinar cells present in the epithelial layer of the laying hen oviduct. It is not present in goblet cells. Although the initiation of a synthesis may be triggered by progesterone, it is still not clear whether different hormone dependent proteins are localized in the same granules in both the adult hen and the immature chick.     

Fine structural aspects of silk secretion in a spider (Araneus diadematus). I. Elaboration in the pyriform glands

Pyriform glands of Araneus diadematus which produce the silky material used for the attachment discs of the web, consist of two kinds of secretory cells. One, located in the distal half of the glands, elaborates finely fibrillar proteinic granules through an extensive rough endoplasmic reticulum; another, in the proximal half of the glands, secretes complex-structured granules in areas of the cell where Golgi and ergastoplasmic cisternae are equally developed. The opaque nascent granules of secretion appear in swollen Golgi saccules. These aggregate in superposed circular interconnected layers leaving an electron-lucent space between them; in the course of maturation the space is progressively filled with a fibrillar material. Histochemical tests suggest that the secretory product of the proximal half is mainly a protein rich in acidic groups and associated with a carbohydrate component. The two products, extruded by a merocrine process, form respectively the core and the envelope of the silk fibre. The dual composition of the pyriform gland silk, which did not appear from the results of chemical analyses, is compared to the association of fibroin and sericin in Lepidoptera silk and to certain double-layered Trichoptera silks.     

Cytochemical studies of GERL and its role in secretory granule formation in exocrine cells

Synopsis the structure and cytochemistry of GERL was studied in several different exocrine secretory cells, including the exorbital lacrimal gland, parotid, lingual serous (von Ebner's), submandibular, and sublingual salivary glands, and exocrine pancreas of the rat; the lacrimal, parotid and pancreas of the guinea-pig; and the lacrimal gland of the monkey. GERL was morphologically and cytochemically similar in all cell types studied. It was located in the inner Golgi region and consisted of cisternal and tubular portions. Immature secretory granules were in continuity with GERL through multiple tubular connections. Modified cisternae of endoplasmic reticulum, with ribosomes only on one surface, closely paralleled parts of GERL. GERL and immature granules were intensely reactive for acid phosphatase activity, while the inner Golgi saccules were reactive for thiamine pyrophosphatase and nucleoside diphosphatase activities. In the rat exorbital lacrimal and parotid glands, reaction product for endogenous peroxidase, a secretory enzyme, was present in the endoplasmic reticulum, Golgi saccules, immature and mature secretory granules. GERL was usually free of reaction product or contained only a small amount. The widespread occurrence of GERL in secretory cells, and its intimate involvement with the formation of granules, suggest that it is an integral component of the secretory process.     

Immunocytochemical localization of parathyroid hormone in hamster parathyroid gland

The immunocytochemical localization of parathyroid hormone was examined in the hamster parathyroid gland by using the protein A-gold technique. Protein A-gold particles were concentrated over secretory granules, large secretory granules thought to be storage granules and Golgi vacuoles. No protein A-gold particles were detected over large vacuolar bodies and cisternae of the granular endoplasmic reticulum.     

Number and size of intracisternal granules in the adipokinetic hormone-secreting cells of locusts: a phase-dependent characteristic

Abstract.The intracisternal (= ergastoplasmic) granules in the adipokinetic hormone-secreting cells of the glandular lobes of the corpora cardiaca in Locusta migratoria migratorioides represent accumulations of adipokinetic prohormones within cisternae of the rough endoplasmic reticulum. Solitary locusts have more and larger intracisternal granules than gregarious locusts. This coincides with the general locomotor activity and thus the energy metabolism in solitary locusts being quite different from that of gregarious locusts, which apparently has consequences for the amounts of adipokinetic hormones synthesized and/or released and, consequently, for the storage of these hormones in the intracisternal granules. These granules apparently function as supplementary stores of secretory material.     

Ultrastructural changes in the oviduct of the laying hen during the laying cycle

The ultrastructural changes occurring in the fully functional oviduct of Isa Brown laying hens were studied during various stages of the laying cycle. Hens were killed at different positions of the egg in the oviduct. The oviduct was lined by ciliated and non-ciliated cells (also referred to as granular cells). The granular cells in the infundibulum contributed to secretion during egg formation, whereas ciliated cells showed little evidence of secretion. Ultrastructural changes were recorded in the granular and glandular cells of the distal infundibulum. In the magnum, the surface ultrastructure revealed glandular openings associated with the ciliated and granular cells. Cyclic changes were recorded in the glandular cells of the magnum. With respect to the three observed types of glands, the structure of gland type A and C cells varied at different egg positions in the oviduct, whereas type B cells represented a different type of gland cell containing amorphous secretory granules. The surface epithelium of the isthmus was also lined by mitochondrial cells. Two types of glandular cell (types 1 and 2) were recorded in the isthmus during the laying cycle. Intracisternal granules were found in type 2 cells of the isthmus. A predominance of glycogen particles occurred in the tubular shell gland. The granular cells in the shell gland contain many vacuoles. During egg formation, these vacuoles regressed following the formation of extensive rough endoplasmic reticulum; the reverse also occurred. The disintegrated material found in the vacuoles may have been derived from the disintegrating granules. The Physiology Teaching Unit, University of New England, provided financial support to K. Chousalkar for this study.     

Ultrastructure of the sexual segments of the kidney in male and female lizards,Cnemidophorus l. lemniscatus (L.)

Summary Kidneys of adult male and female lizards were studied by electron microscopy, in order to understand the ultrastructure of the collecting duct and a differentiated part thereof, the sexual segment, which is an important accessory sexual organ. First portion of sexual segment in males: The cells are filled with large secretory granules of a wide range of opacities. The granular endoplasmic reticulum is abundant; basal formations of superimposed flat cisternae are frequent. Distended vesicles and microvesicles prevail in the supranuclear, well developed Golgi apparatus. Evidences indicate that secretion of these cells is holocrine. Second portion of sexual segment in males: All of the secretory granules are apical in location and relatively electron-opaque; they show a denser core. This core is formed by a substance which, after lying in contact with ribosomes, enters the secretory vesicles of the highly developed Golgi apparatus. A lighter substance is then condensed around it. The secretion of the granules is merocrine. The granular endoplasmic reticulum is very abundant in these cells, but basal ergastoplasmic formations are lacking. Sexual segment in females: The cells show features similar to those of the male first portion, but they are smaller. Undifferentiated collecting duct: Most of the cells are mucigenic. They have small ovoid, apical secretory granules. The density of the granules varies from cell to cell; when they are electron-lucent, they exhibit laminar or dotted opaque figures. Moderately developed Golgi apparatus and granular endoplasmic reticulum, as well as elongated mitochondria, occur in mucigenic cells. Intercalated among the latter are non-secretory cells. They have very abundant mitochondria, numerous microvilli, many pinocytic and smooth-membrane vesicles, whereas the organelles participating in synthetic processes are poorly developed; their function is most likely related to active solute transport.     

Zinc Secretion in the Oviduct of the Coturnix Quail

The oviduct from laying quail were used to investigate mechanisms of trace mineral secretion and the possible role of metallothionein in this process. Secretion of zinc occurred maximally at pH 5.4, which is close to the normal pH of the oviduct. Secretion occurred to a much greater extent in the isthmus and shell gland than in the magnum, the major protein-secretory section of the oviduct. Intraperitoneal administration of cadmium resulted in a marked reduction in Zn secretion from the oviduct of laying quail. This effect could not be correlated with metallothionein since metallothionein could not be detected in any section of the oviduct in control or Cd-induced quail. Small-molecular-weight metal-binding ligands were present in the isthmus and shell gland, which may play a role in trace mineral mobilization. Histological evaluation by light and elelctron microscopy show that Zn is transported from the smooth muscle cells through the connective tissue matrix in the extracellular space to the epithelial goblet cells. Presumably, Zn and other trace minerals are secreted from the secretory goblet cells into the egg.     

Ultracytochemistry of glycoproteins in the eccrine nasolabial glands of the North American raccoon (Procyon lotor)

The distribution and quality of glycoproteins was studied by means of electron microscopic cytochemical methods, particularly lectin cytochemistry, in the secretory cells of the eccrine nasolabial glands of the North American raccoon (Procyon lotor). In the dark and clear glandular cells, complex glycoconjugates were demonstrable, predominantly, in secretory granules, the cisternae of the Golgi apparatus, the surface coat of the plasma membrane, and as glycogen particles. Secretory granules found in the dark cells contained a variety of saccharide residues, such as α-d-mannose, β-d-galactose, β-N-acetyl-d-glucosamine and sialic acid. Several sugars were also detectable in the surface coat of the plasma membrane and the Golgi apparatus.The results obtained may be helpful to understand the specific functions of the glandular secretions of the raccoon nasolabial glands. These could be, particularly, binding of water on the snout surface and protection against microbial hazards, to maintain the structural and functional integrity of the relatively thin snout epidermis in carnivores.     

The fine structure of the secretory cells of the uterus (shell gland) of the chicken

The secretory processes in the shell gland of laying chickens were the subject of this study. Three cell types contribute secretory material to the forming egg: ciliated and non-ciliated columnar cells of the uterine surface epithelium, and cells of tubular glands in the mucosa. The ciliated cells as well as the non-ciliated cells have microvilli, which undergo changes in form and extent during the secretory cycle. At the final stages of shell formation they resemble stereocilia. It is postulated that the microvilli of both cells are active in the production of the cuticle of the shell. The ciliated cell which has both cilia and microvilli manufactures secretory granules which arise from the Golgi complex in varying amounts throughout the egg laying cycle. Granule production reaches its greatest intensity during the early stages of shell deposition. The ciliated cell probably supplies proteinaceous material to the matrix of the forming egg shell. The non-ciliated cell has only microvilli. Secretory granules, containing an acid mucopolysaccharide, arise from the Golgi complex. Some granules are extruded into the uterine lumen where they supply the egg shell with organic matrix. Others migrate towards the supranuclear zone. Here a number of them disintegrate. This is accompanied by the formation of a large membraneless space, which is termed “vacuoloid.” Subsequently the vacuoloid regresses and during regression an extensive rough endoplasmic reticulum with numerous polyribosomes of spiral configuration appears. It is suggested that material in the vacuoloid originating from the disintegrating granules is resynthesized and utilized for the formation of secretory product. The uterine tubular gland cells have irregular, frondlike microvilli. During egg shell deposition, these microvilli form large blebs and are probably related to the elaboration of a watery, calcium-containing fluid.     

Ultrastructure of the tubular accessory gland in Haemaphysalis longicornis (Acari: Ixodidae)

The paired tubular accessory glands in Haemaphysalis longicornis open at the junction of the cervical and the vestibular parts of vagina via short and narrow ducts. The pseudostratified columnar glandular epithelium covered by the muscle layer consists of both secretory and supporting cells. As feeding proceeds, the secretory cells increase in volume. In ovipositing females, well-developed rough endoplasmic reticulum, the Golgi complex, and membranebound granules that are undergoing exocytosis suggest that the secretory cells are involved in protein synthesis. However, in virgin females that fed 10 days, only small dense granules and no secretion activity were observed. The secretions from the tubular accessory gland may be released into the genital tract during the egg passage through the vagina. However, the supporting cells located between the secretory cells become slender during feeding, cohere to each other at the luminal side, and have a very narrow attachment at the basement membrane. Supporting cells probably help maintain secretory cell shape especially during granular discharge into the lumen. © 1994 Wiley-Liss, Inc.     

Freeze-fracture study of the rat parathyroid gland under hypo- and hypercalcemic conditions,with special reference to secretory granules

Summary Freeze-fracture images of the parenchymal cells in the parathyroid gland of rats were observed after vitamin D₂ plus calcium chloride-suppression and EGTA-activation of secretion. In cells of the suppressed glands, large bulges protruded from the Golgi cisternae, and large granules with a stalk, which are identified as storage granules, suggest that, during maturation, some storage granules may be connected by long tubules with the Golgi cisternae and supplied with secretory products from the Golgi cisternae via these tubules.In the activated glands, presumptive exocytotic and endocytotic specializations of intramembranous particles of the parenchymal cell plasma membrane were frequently observed. In addition, elevations and complementary shallow depressions of various shape and extent were occasionally encountered in the intercellular space. From their morphological characteristics it was concluded that these originated from secretory granule cores, which are discharged from the parenchymal cells into the intercellular space by exocytosis, and it was suggested that discharged granule cores may retain their spherical shape until they fuse to form a flat conglomerate.     

Relationship between the golgi apparatus, gerl, and secretory granules in acinar cells of the rat exorbital lacrimal gland

The method of secretory granuleformation in the acinar cells of the rat exorbital lacrimal gland was studied by electron microscope morphological and cytochemical techniques. Immature secretory granules at the inner face of the Golgi apparatus were frequently attached to a narrow cisternal structure similar to GERL as described in neurons by Novikoff et al. (Novikoff, P. M., A. B. Novikoff, N. Quintana, and J.-J. Hauw. 1971. J. Cell Bio. 50:859-886). In the lacrimal gland. GERL was located adjacent to the inner Golgi saccule, or separated from it by a variable distance. Portions of GERL were often closely paralleled by modified cisternae of rough endoplasmic reticulum (RER), which lacked ribosomes on the surface adjacent to GERL. Diaminobenzidine reaction product of the secretory enzyme peroxidase was localized in the cisternae of the nuclear envelope, RER, peripheral Golgi vesicles, Golgi saccules, and immature and mature secretory granules. GERL was usually free of peroxidase reaction product or contained only a small amount. Thiamine pyrophosphatase reaction product was present in two to four inner Golgi saccules; occasionally, the innermost saccule was dilated and fenestrated, and contained less reaction product than the next adjacent saccule. Acid phosphatase (AcPase) reaction product was present in GERL, immature granules, and, rarely, in the innermost saccule, but not in the rest of the Golgi saccules. Thick sections of AcPase preparations viewed at 100 kV revealed that GERL consisted of cisternal, and fenestrated or tublular portions. The immature granules were attached to GERL by multiple connections to the tublular portions. These results suggest that, in the rat exorbital lacrimal gland, the Golgi saccules participate in the transport of secretory proteins, and that GERL is involved in the formation of secretory granules.     

北京鸭产卵期输卵管管状腺细胞超微结构研究

用电子显徽镜对北京鸭输卵管管状腺细胞进行观察。鸭输卵管由五部分组成:漏斗、蛋白分泌部、峡部、壳腺和阴道。蛋白分泌部的管状腺细胞有四种类型。A型细胞有电子密度深色颗粒;B型细胞充满了无定型低电子密度物质;C型细胞具有非常明显的粗面内质网和高尔基复合体;D型细胞是由致密的颗粒和低电子密度的颗粒所组成,腔内充满分泌颗粒。我们在这篇文章中分析了蛋白分泌周期的四个不同阶段。     

Electron microscopic and cytochemical studies of the mouse subcommissural organ

Summary In mice most of the ependymal cells of the subcommissural organ (SCO cells) are densely packed with dilated cisternae of the endoplasmic reticulum (ER) containing either finely granular or flocculent materials. The well developed supra-nuclear Golgi apparatus consists of stacks of flattened saccules and small vesicles; the two or three outer Golgi saccules are moderately dilated and exhibit numerous fenestrations; occasional profiles suggesting the budding of coated vesicles and formation of membrane-bound dense bodies from the ends of the innermost Golgi saccules are seen. A few coated vesicles and membrane-bound dense bodies of various sizes and shapes are also found in the Golgi region.The contents of the dilated ER cisternae are stained with periodic acid-silver methenamine techniques. In the Golgi complex the two or three inner saccules are stained as deeply as the dense bodies, and the outer saccules are only slightly stained. The stained contents of ER cisternae are more electron opaque than those of the outer but less opaque than those of the inner Golgi saccules and the dense bodies.Acid phosphatase activities are localized in the dense bodies, some of the coated vesicles in the Golgi region, and in the one or two inner Golgi saccules.On the basis of these results the following conclusions have been reached: (1) In mouse SCO cells the finely granular and the flocculent materials in the lumen of ER cisternae contain a complex carbohydrate(s) which is secreted into the ventricle to form Reissner's fiber; (2) the secretory substance is assumed to be synthesized by the ER and stored in its cisternae, and the Golgi apparatus might play only a minor role, if any, in the elaboration of the secretory material; (3) most of the dense bodies in the mouse SCO cells are lysosomal in nature instead of being so-called dark secretory granules.Sponsored by the National Science Council, Republic of China.     

Concentration of amylase along its secretory pathway in the pancreatic acinar cell as revealed by high resolution immunocytochemistry

Summary The modified protein A-gold immunocytochemical technique was applied to the localization of amylase in rat pancreatic acinar cells. Due to the good ultrastructural preservation of the cellular organelles obtained on glutaraldehyde-fixed, osmium tetroxide-postfixed tissue, the labelling was detected with high resolution over the cisternae of the rough endoplasmic reticulum (RER), the Golgi apparatus, the condensing vacuoles, the immature pre-zymogen granules, and the mature zymogen granules. Over the Golgi area, the labelling was present over the transitional elements of the endoplasmic reticulum, some of the smooth vesicular structures at thecis- andtrans-faces and all the different Golgi cisternae. The acid phosphatase-positive rigidtrans-cisternae as well as the coated vesicles were either negative or weakly labelled. Quantitative evaluations of the degree of labelling demonstrated an increasing intensity which progresses from the RER, through the Golgi, to the zymogen granules and have identified the sites where protein concentration occurs. The results obtained have thus demonstrated that amylase is processed through the conventional RER-Golgi-granule secretory pathway in the pancreatic acinar cells. In addition a concomitance has been found between some sites where protein concentration occurs: thetrans-most Golgi cisternae, the condensing vacuoles, the pre- and the mature zymogen granules, and the presence of actin at the level of the limiting membranes of these same organelles as reported previously (Bendayan, 1983). This suggests that beside their possible role in transport and release of secretory products, contractile proteins may also be involved in the process of protein concentration.     

Ultrastructural enzyme-cytochemical study of the intrinsic glandular cells in the corpus cardiacum of Locusta migratoria: relation to the secretory and endocytotic pathways,and to the lysosomal system

Summary Ultrastructural aspects of the secretory and the endocytotic pathways and the lysosomal system of corpus cardiacum glandular cells (CCG cells) of migratory locusts were studied using morphological, marker enzyme, immunocytochemical and tracer techniques. It is concluded that (1) the distribution of marker enzymes of trans Golgi cisternae and trans Golgi network (TGN) in locust CCG cells corresponds to that in most non-stimulated vertebrate secretory cell types; (2) the acid phosphatase-positive TGN in CCG cells is involved in sorting and packaging of secretory material and lysosomal enzymes; (3) these latter substances are produced continuously; (4) at the same time, superfluous secretory granules and other old cell organelles are degraded; (5) the remarkable endocytotic activity in the cell bodies and the minor endocytotic activity in cell processes are coupled mainly to constitutive uptake of nutritional and/or regulatory (macro)molecules, rather than to exocytosis; (6) plasma membrane recycling occurs mainly by direct fusion of tubular endosomal structures with the plasma membrane and little traffic passes the Golgi/TGN; and (7) so-called cytosomes arise mainly from autophagocytotic vacuoles and represent a special kind of complex secondary lysosomes involved in the final degradation of endogenous (cell organelles) and exogenous material.     

Enzyme modulation of the Golgi apparatus and GERL: a cytochemical study of parotid acinar cells

The distribution of thiamine pyrophosphatase (TPPase) and acid phosphatase (AcPase) has been examined in resting parotid acinar cells as well as during decreased and increased secretory granule production. In resting acinar cells, TPPase activity was restricted to the trans Golgi saccules and AcPase activity was localized in GERL and immature secretory granules. Although secretory granule production is diminished during ethionine intoxication, no significant alteration in the distribution of either TPPase or AcPase was noted. However, marked changes in enzyme localization, especially of TPPase, occurred during accelerated secretory granule production. The alterations were essentially the same for all of the conditions studied (recovery from ethionine treatment, recovery from a protein depletion diet, secretory stimulation with isoproterenol, and postnatal maturation of the parotid gland). During maximal secretory granule production, TPPase activity was localized not only in the trans Golgi saccules, but also in GERL-like cisternae and immature secretory granules. The immature secretory granules were often in continuity with the GERL-like cisternae. At the same time that the TPPase activity was increased, the AcPase activity was frequently diminished. These modulations in enzyme activity provide evidence that GERL is derived from the trans Golgi saccule.