Histofluorescence and ultrastructural observations of small intensely fluorescent (SIF) cells in the superior sympathetic ganglion of the guinea pig

Summary Amine-containing small intensely fluorescent (SIF) cells are ubiquitous in vertebrate sympathetic ganglia and, in some species, SIF cells have been identified as interneurons. The hypothesis proposed in this study is that SIF cells in superior sympathetic ganglia of the guinea pig function as interneurons, with efferent connections characteristic for the species. Fluorescence (catecholamine) microscopy and 5-hydroxydopamine marker for electron microscopy were used to study SIF cells, their processes and connections in this ganglion.Brightly fluorescent fibers were seen attached to virtually all SIF cells, and were of two types. The first type, single or arranged in cords, interconnected elements of the SIF-cell system; these apparent linkages joined individual SIF cells as well as adjacent clusters. The electron-microscopic evidence for synaptic contacts between SIF cells warrants the claim that integrated action is a presumed function of these elements. The second type of SIF-cell process was generally of greater length. These individual, branching fibers made presumed connections with dendrites of most principal ganglionic neurons. This arrangement suggested by histofluorescence preparations was confirmed by electron microscopy to involve synaptic connections, and the postsynaptic element was shown to be continuous with the perikaryon of the principal ganglionic neuron. Ultrastructural evidence that collections of dense-cored vesicles occur within processes of both principal ganglionic neurons and SIF cells, in proximity to unsheathed portions of plasma membrane, leads to the conclusion that interstitial diffusion of catecholamine from both may occur; the finding of SIF cell processes adjacent to fenestrated blood vessels suggests that catecholamine may also be transported through capillaries.     

Electron microscopic research on the manifestations of transport-metabolic interactions in intraocular nerve tissue grafts

Electron microscopic study of intraocular grafts of the septal and hippocampal nervous tissue revealed intensive transport and metabolic interactions between various types of the cells. High level of transport exists between the recipient's blood and intraocular fluid, on the one hand, and the graft, on the other one; the abundance of pinocytotic vesicles in the endothelium, pericytes and the glial end-feet of the capillaries, and the presence of microvilli and cilia on the graft limiting glia. Signs of active communications between interstitial glial cells, as well as between gliocytes and neurons, such as pinocytosis and gap junctions were observed. Similar interactions exist between various parts of nerve cells. Besides, there is an evidence of microphagocytic interactions, particularly between pre- and postsynaptic elements, as shown by the presence of so-called spinules. An unusual fact was observed of internalization of cytoplasmic fragments of the degenerating neuron by contacting synaptic boutons. It is suggested that the high level of transport and metabolic processes may reflect adaptive and compensatory processes in the nervous tissue developing under strict limitations of the neural and neurotrophic influences.     

Surface configuration of mesothelial cells in effusions. A comparative light microscopic and scanning electron microscopic study.

Surface configuration of mesothelial cells identified by light microscopy (LM) has been studied by scanning electron microscopy (SEM). It has been shown that mesothelial cells may have a variable SEM appearance. The surfaces of a small proportion of mesothelial cells are covered by regular microvilli (MV) and show openings of the pinocytotic vesicles. The surfaces of the majority of these cells are covered by vesicles or blebs. An intermediate population of mesothelial cells, i.e., cells displaying side-by-side blebs and MV, has also been observed. The latter cells no longer display pinocytotic vesicles. Occasional mesothelial cells have smooth surfaces. It has been shown by LM and transmission electron microscopy that cells with blebs are viable and capable of mitotic activity. It is concluded that mesothelial cells, detached from their epithelial setting, lose microvilli and pinocytotic vesicles and acquire surface blebs. The possible relationship between mesothelial cells and macrophages based on surface features has been discussed.     

Absorption of elastase through the jejunal mucosa of the rat. An immunocytochemical study

In order to reveal the absorption process of elastase from the intestine, hog pancreatic elastase was injected into the ligated jejunum lumen of the rat, and the tissues were cytochemically observed at various times after injection. The peroxidase anti-peroxidase (PAP) method using anti-hog-elastase rabbit antibody was used for light microscopy, and the anti-elastase Fab'-peroxidase conjugate was used for electron microscopy. The tissues stained by the PAP method exhibited a dense deposition of reaction products on the luminal surface of epithelial cells and a moderate deposition in the blood and lymph capillaries of the intestinal villi. Immunoelectron microscopy revealed that the reaction product was deposited on the surface of the microvilli and in their pocketing; some was found in the pinocytotic vesicles in the terminal-web area and on the inner surface of the enlarged smooth endoplasmic reticulum. Round droplets which gave a positive reaction were found in the widened intercellular cleft and the thick basement membrane lining the blood capillaries and lymphatics. The jejunum retained its normal ultrastructure. The results indicate that the elastase molecules, which were introduced into the rat jejunum lumen, were absorbed without being decomposed through healthy intestinal epithelial cells by pinocytosis and translocated into blood and lymph capillaries.     

Ultrastructure of the endolymphatic sac in the mouse.

The ultrastructure of the endolymphatic sac (ES) in the mouse was examined by light and electron microscopy. This organ was divided into three parts: proximal, intermediate and distal. In the proximal portion of the ES, the epithelium consisted of thin squamous cells. The epithelial cells had acquired basolateral processes, numerous small vesicles and well-developed Golgi apparatus. In the intermediate portion, the epithelium consisted of columnar or cuboidal cells. The epithelial cells could be classified into two types: type I and type II. The type I cells had abundant microvilli, pinocytotic vesicles, vacuoles, multivesicular bodies, lysosomes and mitochondria. The type II cells had fewer numbers of these organelles. A few free-floating cells could be observed in the lumen of this intermediate portion, most of which were macrophages. In the distal portion, the epithelium consisted of squamous or cuboidal cells. The epithelial cells had a few cytoplasmic organelles. In the ultrastructural study, each portion of the mouse ES was found to have a very distinct morphological feature. It was suggested that each of these three portions has a different function.     

Absorption of elastase through the jejunal mucosa of the rat

Summary In order to reveal the absorption process of elastase from the intestine, hog pancreatic elastase was injected into the ligated jejunum lumen of the rat, and the tissues were cytochemically observed at various times after injection. The peroxidase anti-peroxidase (PAP) method using anti-hog-elastase rabbit antibody was used for light microscopy, and the anti-elastase Fab-peroxidase conjugate was used for electron microscopy. The tissues stained by the PAP method exhibited a dense deposition of reaction products on the luminal surface of epithelial cells and a moderate deposition in the blood and lymph capillaries of the intestinal villi. Immunoelectron microscopy revealed that the reaction product was deposited on the surface of the microvilli and in their pocketing; some was found in the pinocytotic vesicles in the terminal-web area and on the inner surface of the enlarged smooth endoplasmic reticulum. Round droplets which gave a positive reaction were found in the widened intercellular cleft and the thick basement membrane lining the blood capillaries and lymphatics. The jejunum retained its normal ultrastructure. The results indicate that the elastase molecules, which were introduced into the rat jejunum lumen, were absorbed without being decomposed through healthy intestinal epithelial cells by pinocytosis and translocated into blood and lymph capillaries.     

双峰驼肾重吸收机能的细胞学证据

电镜下观察了18峰双峰驼（Camelus bactrianus)肾脏细胞的超微结构,探究驼肾重吸收机能的形态学证据。结果显示,驼肾近曲小管的刷状缘高而密集,上皮细胞胞质顶端具有丰富的管泡结构,侧基底指状突起和基底质膜内褶多而明显,板状嵴线粒体发达。远曲小管和远直小管游离面微绒毛短而稀少,胞质线粒体排列密集,质膜内褶更为发达。集合小管上皮包括多量的亮细胞和少量的暗细胞两种类型,亮细胞结构简单,线粒体稀少,暗细胞线粒体密集,由皮质至髓质,暗细胞数量呈递减趋势,但内髓仍见暗细胞分布。皮质间质极少,志细血管丰富,管壁内皮菲薄有孔。髓质直小血管亦为有孔内皮。上述结构特征表明,双峰驼具有很强的重吸收能力,与其节水耐干渴特性相适应。     

Electron microscopic studies on the pineal organ of the antarctic penguin, (Pygoscelis papua)

The pineal organ of the migratory antarctic penguin, Pygoscelis papua, has a lobular structure. Clusters formed by different types of parenchymal cells are separated by connective tissue septa containing blood vessels. The predominant cell type displays a well-developed Golgi complex, free ribosomes, clear and granular vesicles (secretory granules), and lysosomes. Other cell types found in the gland are supporting and ependymal-like cells. The former contain dense bodies and filament bundles, the latter possess abundant cilia and clusters of ribosomes. Typical photoreceptor elements are lacking. Blood vessels are located within a perivascular space bordered by basal laminae. This perivascular space extends between the basal protrusions of the parenchymal cells. The presence of pinocytotic vesicles, secretory granules and cytoplasmic processes in the vicinity of these spaces suggests active sites of transport and exchange of substances. Intercellular conaliculi-like spaces are surrounded by parenchymal cells rich in microvilli. These cancliculi are continuous with the cavities (invaginations) of secretory and other parenchymal cells.     

Different types of small granule-containing cells and neurons in the guinea-pig adrenal medulla

Summary An electron microscopic, histoand biochemical study was carried out on the adrenal medulla of newborn and adult guinea-pigs giving special emphasis to small granule-containing (SGC) cells. Adrenaline (A) was the predominating catecholamine (CA) both in newborn (70–90 % of total CA) and adult (85–90%) guinea-pig adrenals. In analogy to the biochemical findings electron microscopy revealed a high predominance of A cells, which contained large granular vesicles with an average diameter of 180 nm. Most noradrenaline (NA) storing cells showed granular vesicles of a considerably smaller average diameter (80 nm) and had a higher nuclear-cytoplasmic ratio. These cells were termed SGC-NA cells. NA cells with large granular vesicles (average diameter 170 nm) were extremely rare. Another type of SGC cells contained granular vesicles with cores of low to medium electron-density (SGC-NA-negative cells). Biochemical determinations made it unlikely that these cells contained predominantly dopamine (DA). SGC cells were scarcely innervated by cholinergic nerves. They formed processes, which were found both in the adrenal cortex and medulla contacting blood vessels including sinusoid capillaries, steroid producing cells of the reticularis and fasciculata zone and processes, which were interpreted to belong to medullary nerve cells.Two types of neurons were present in the guinea-pig adrenal medulla, one resembling the principal neurons in sympathetic ganglia, the other, which, according to its morphology, occupied an intermediate position between principal neurons and SGC cells.In adrenomedullary grafts under the kidney capsule, which were studied three weeks after transplantation, ordinary A cells resembled SGC-NA negative cells with respect to their ultramorphology. Processes of transplanted principal neurons showed uptake of 5-hydroxydopamine and, hence, were considered to be adrenergic. Despite the lack of extrinsic nerves to the transplants, few principal neurons received cholinergic synapses, the origin of which is uncertain to date.Supported by a grant from Deutsche Forschungsgemeinschaft (Un 34/4)Dedicated to Professor H. Leonhardt in honor of his 60th birthday.     

Development of extracellular matrix in chick paravertebral sympathetic ganglia

Alcian blue staining coupled with enzyme digestion or critical electrolyte staining revealed differences in the development of extracellular matrix (ECM) within sympathetic ganglia compared with the surrounding capsule. On day 5 of chick development (Hamburger-Hamilton stage 26) only hyaluronic acid (HA) could be detected in the ECM surrounding condensing primary ganglia. By day 7 (st 30) the ganglionic capsule contained HA, as well as sulfated glycosaminoglycans (GAGs), and this pattern continued into the adult stage. During the later stages of embryonic life (st 41-45) satellite cells appear, showing fine structural characteristics that point to their role in the secretion of intraganglionic ECM. Only during these stages could ECM be detected histochemically within ganglia, the same stages (days 15-19) when routine electron microscopic methods reveal collagen fibrils embedded in a granular ground substance. Thus, the intraganglionic environment appears as a separate compartment free of detectable amounts of GAG until late embryonic stages when ECM is secreted around satellite cells. This developmental pattern could represent a role of ECM in the histological stabilization of ganglia during the late stages of differentiation, since the appearance of intraganglionic ECM is correlated with the appearance of small dense-cored vesicles characteristic of adult neurons. The developmental pattern of ECM in differentiating sympathetic ganglia is compared with that of other tissues that undergo condensation and morphogenesis.     

Electron microscopic research on the mechanism of intestinal secretion

Electron microscopic investigation of the rat small intestine revealed a great number of vesicles 50-75 nm in diameter with enterocyte microvilli. The number of vesicles increased with the increase of digestive activity in the small intestine. Vesicles were formed by gemmation of enterocyte microvilli from the lateral membrane in contraction of microvillous actin skeleton. Simultaneously with the production of exocytotic vesicles, the formation of pinocytotic vesicles in the base of microvilli was observed. There is a supposition that the vesicle gemmation is a natural process of the intestinal secretion to fulfil numerous important function: it promotes the penetration of enterocyte hydrolases into the parietal layer; equilibrates an increase in the enterocyte volume during absorption. This is a possible way of translocation of synthesized enzymes into the cytoplasm and of transport proteins on the apical surface of epithelial cells.     

Ultrastructural changes induced by juvenile hormone analogue in oöcyte membranes of apterous4Drosophila melanogaster

Egg chambers from apterous⁴ (ap⁴), a female sterile mutant of Drosophila melanogaster, show none of the microvilli or pinocytotic vesicles which are a prominent feature of the membrane of the wild-type vitellogenic oöcyte. The studies reported here show that a juvenile hormone analogue (ZR515) stimulates formation of microvilli and pinocytotic vesicles in oöcytes of ap⁴ flies. Within 12 hr after topical application of ZR515 to homozygous ap⁴ females the oöcyte membranes exhibit extensive microvilli and pinocytotic activity. The follicle-cell surface adjoining the oöcyte also shows some changes. In vitro studies in which ap⁴ ovaries were incubated in Schneider's Drosophila tissue-culture medium in the presence of ZR515 with or without female haemolymph, or in the absence of ZR515, showed that the analogue acts alone directly on the ovary to cause formation of microvilli and pinocytotic vesicles on the oöcyte membrane.     

Effects of light on ocelli of seastars

Summary Dark- and light-adapted ocelli of three seastars (Patina miniata, Leptasterias pusilla, Henricia leviuscula) were studied by transmission and scanning electron microscopy. In the dark-adapted state the process of each receptor cell is relatively devoid of clear vesicles. Numerous long microvilli arise from the tips and sides of the processes. Cilia from the sensory processes project into the lumen of an ocellus; they are unconnected to the microvilli. In light-adapted ocelli each process is filled with clear pinocytotic vesicles of varying size. The microvilli are now irregular. Many lie free in the lumen of an ocellus or within phagocytic vacuoles in the supportive and corneal cells. These findings are evidence of a microvillar (rhabdomeric) type of photoreceptor in seastars and of cyclic turnover of receptoral membrane.The authors are grateful to the U.S. Public Health Service for a grant-in-aid of research (EY02229), to the Electron Microscope Laboratory on the Berkeley campus for use of facilities, and to Carol T. Reed for assistance on preliminary studies     

Structural modulation of the surface and cytoplasm of oocytes during vitellogenesis in the lobster,Homarus americanus. An electron microscope-protein tracer study

The present investigation describes the ultrastructural changes which occur at the surface and in the cytoplasm of developing oocytes of the lobster, Homarus americanus, during vitellogenesis. The immature oocytes showed no surface specializations of the oolemma and no pinocytotic activity was observed. Horseradish peroxidase (HRP) tracer studies showed penetration of the tracer into the perivitelline space, but no uptake by the oocytes. The surfaces of oocytes examined during vitellogenesis, when yolk protein accumulation was maximal, exhibited numerous microvilli that projected into the perivitelline space, often appearing to be embedded in the follicular cell mass. In addition, the plasma membrane of vitellogenic oocytes contained many pinocytotic pits frequently situated at the bases of microvilli. The perivitelline space was engorged with electrondense material which appeared similar to that contained in pinocytotic structures of the oocytes. Vitellogenic oocytes incubated in HRP showed uptake of tracer reaction product by the coated pits and vesicles of the oolemma. Aggregation and subsequent fusion of these vesicles into large multivesicular bodies of ingested material were also observed in vitellogenic oocytes. Animals artificially induced to undergo vitellogenesis exhibited modulations of oocyte ultrastructure similar to those of normal vitellogenesis, notably, pinocytotic incorporation of extra-oocytic material and hypertrophy of oocyte surface microvilli. This study supports the hypothesis for a dual source of yolk protein in the American lobster.     

Rapid changes in synaptic vesicle cytochemistry after depolarization of cultured cholinergic sympathetic neurons

Sympathetic neurons taken from rat superior cervical ganglia and grown in culture acquire cholinergic function under certain conditions. These cholinergic sympathetic neurons, however, retain a number of adrenergic properties, including the enzymes involved in the synthesis of norepinephrine (NE) and the storage of measurable amounts of NE. These neurons also retain a high affinity uptake system for NE; despite this, the majority of the synaptic vesicles remain clear even after incubation in catecholamines. The present study shows, however, that if these neurons are depolarized before incubation in catecholamine, the synaptic vesicles acquire dense cores indicative of amine storage. These manipulations are successful when cholinergic function is induced with either a medium that contains human placental serum and embryo extract or with heart-conditioned medium, and when the catecholamine is either NE or 5-hydroxydopamine. In some experiments, neurons are grown at low densities and shown to have cholinergic function by electrophysiological criteria. After incubation in NE, only 6% of the synaptic vesicles have dense cores. In contrast, similar neurons depolarized (80 mM K+) before incubation in catecholamine contain 82% dense-cored vesicles. These results are confirmed in network cultures where the percentage of dense-cored vesicles is increased 2.5 to 6.5 times by depolarizing the neurons before incubation with catecholamine. In both single neurons and in network cultures, the vesicle reloading is inhibited by reducing vesicle release during depolarization with an increased Mg++/Ca++ ratio or by blocking NE uptake either at the plasma membrane (desipramine) or at the vesicle membrane (reserpine). In addition, choline appears to play a competitive role because its presence during incubation in NE or after reloading results in decreased numbers of dense-cored vesicles. We conclude that the depolarization step preceding catecholamine incubation acts to empty the vesicles of acetylcholine, thus allowing them to reload with catecholamine. These data also suggest that the same vesicles may contain both neurotransmitters simultaneously.     

Growth cones of cultured sympathetic neurons contain adrenergic vesicles

The growth cones of dissociated rat sympathetic neurons developing in culture were fixed with potassium permanganate to visualize vesicular stores of norepinephrine through the formation of granular precipitates. It was found that growth cones contain numerous small granular vesicles (SGV) 40-60 nm in diameter. The majority of the SGV was present in the varicosity of the growth cone but SGV also occurred in filopodia. The SGV appeared in clusters or scattered throughout the varicosity. Treatment of the cultured neurons, before fixation, with reserpine, which depletes catecholamine stores by blocking uptake into vesicles, resulted in the presence of small clear vesicles. In contrast, growth cones of nonadrenergic sensory neurons dissociated from dorsal root ganglia and fixed with permanganate lacked SGV and possessed small clear vesicles. These observations indicate that the growth cones of cultured sympathetic neurons contain norepinephrine, suggest that the norepinephrine is stored in synaptic vesicles, and raise the question whether this transmitter plays a role in early axon-target cell interactions during synapse formation.     

Microvascularization of the rat superior cervical ganglion. A three-dimensional observation.

The three-dimensional image of the microvascularization of the rat superior cervical ganglion (SCG) was examined using the vascular corrosion cast technique in conjunction with scanning electron microscopy. It was found that the rat SCG was a highly vascularized organ. Arteries supplying the ganglion gave rise to a subcapsular capillary plexus before branching off to become intraganglionic capillaries. Two types of intraganglionic capillaries, large and small, were observed throughout the organ. Numerous anastomoses among these capillaries were found before they converged into venules and collecting veins. However, a pattern of blood vessels resembling portal-like intraganglionic microcirculation could not be demonstrated.     

Ultrastructure and functional features of midgut of an adult water mite Teutonia cometes (Koch, 1837) (Hydrachnidia: Teutoniidae)

Shatrov, A. B. 2010. Ultrastructure and functional features of midgut of an adult water mite Teutonia cometes (Koch 1837) (Hydrachnidia: Teutoniidae). —Acta Zoologica (Stockholm) 91 : 222–232 The midgut of the adult water mite Teutonia cometes (Koch 1837) (Hydrachnidia: Teutoniidae) was investigated by means of transmission electron microscopy and on semi‐thin sections. The midgut is represented by a blind sac composed of the narrow ventriculus, two proventricular lateral diverticula and three pairs of postventricular caeca. A single‐layered epithelium consists of one type of endodermal digestive cells of quite different shape and size, which may form protrusions into the midgut lumen. The large nuclei are frequently lobed and contain one to three nucleoli. The apical cell membrane forms short scarce microvilli, between their bases the pinocytotic vesicles of unspecific macropinocytosis as well as the narrow pinocytotic canals are formed and immersed into the cell. The intracellular digestion of the food ingested into the midgut after extraintestinal digestion is predominant. The pinocytotic vesicles fuse with small clear vesicles of proposed Golgi origin to form secondary lysosomes. The digestive cells also contain small amounts of rough endoplasmic reticulum, variously structured heterolysosomes, residual materials in the form of both the small electron‐dense bodies and the large variously granulated substances, reserve nutritive materials such as lipid and glycogen, as well as clear vacuoles. Residual materials are obviously extruded from the cells into the gut lumen.     

Fine structure of the area postrema of the rabbit brain

Summary The area postrema of the rabbit, which was perfused with glutaraldehyde and postfixed in osmium tetroxide, was observed under the electron microscope. This area showed neuronal and neuroglial structures similar to those of ordinary cerebral tissue, except for rich blood capillaries, which were surrounded by conspicuous perivascular spaces. Parenchymal cells included a moderate number of small neurons and large numbers of specific astrocyte-like cells. The neuropil consisted of a small number of thin myelinated and many non-myelinated nerve fibers of varying calibers, axo-dendritic synapses, and neuroglial cell processes, leaving no spaces between them. The axons and synaptic terminals contained moderate amounts of granular vesicles, which were similar in size to those found in the hypothalamus and were supposed to contain catecholamine. Glycogen paticles were demonstrated mainly in the cytoplasm of the astrocyte-like cells.