Types of neurons in the central nervous system of the Japanese scallop Mizuhopecten yessoensis (Jay)

Composition of neurons, their structure and neuromediatory specialization in the Japanese scallop ganglia have been studied by means of morphological, morphometrical and histochemical methods. Three groups of neurons, differing in their histophysiological characteristics have been defined. Large neurons are cholinergic ones. A well developed system of smooth membranes and large amount of cytosomes are specific for them. Middle size and small neurons of the I type contain a granular endoplasmic reticulum, elementary neurosecretory peptide granules and are considered as peptidergic. Small neurons of the II type possess increased nuclear-plasmic relations, moderately developed endoplasmic reticulum, positively react to biogenic amines and according to their mediatory specialization are monoaminergic.     

Electron microscopic study of the differentiation of decidual cells. I. The ultrastructure of large decidual cells in the antimesometrial portion of the rat decidua

The large decidual cells (LDC) of the antimesometrial part of decidua in rats of 7-9 days of gestation were studied by electron microscope. The decidual tissue has an epithelium-like pattern of organization. The apical surface of LDC is facing the pericapillar space making numerous villi. Lateral surfaces of these cells maintain close contact with each other by means of zona adhaerens, gap junctions, spot desmosomes and simple junctions. Accumulation of electron dense granules measuring from 0.05 to 0.3 mkm is seen in the apical parts of LDC. The Golgi complex and rough endoplasmic reticulum are much developed. The material of rough endoplasmic reticulum is denser than the cell matrix. Disperse chromatin is seen in the nucleus, whereas the granular component is dominanting in the nucleolus. It is concluded that the LDC may have a high metabolic activity, and that the secretion is a mode of fulfilling specific functions of LDC.     

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.     

The ultrastructure of the small granular, proteinaceous epidermal cells of some British lumbricids (Annelida) and a reassessment of the identity of the so-called albumen cells

The ultrastructure of the small granular, proteinaceous cells of 11 species of lumbricid earthworm is described and no species differences were recorded. The cells are characterized by the presence of membrane-bound, electron dense granules (0.6–0.7 urn in diameter) arising from polarized Golgi systems in close topographical relationship to the granular endoplasmic reticulum. Variations in electron density of the granules appear to be associated with maturation of the granules. The granules show a finely reticular substructure at high magnification. A less than fully mature stage of this cell type is described.
The occurrence of the small granular cell type in the annelids is discussed, as is the possible function of its secretion.
The confusions in the lumbricid literature concerning this cell type are discussed, and the much referred to figure of the 'albumen' cell type in English texts is shown not to be equivalent to the small granular, proteinaceous type referred to in this and a previous histochemical study.     

四种淡水养殖鱼类血细胞的细微结构

四种淡水鱼的血细胞形态基本相似。红血球形态与其他低等脊椎动物基本相似。淋巴球绝大部分是小淋巴球:单核球数量较少;四种鱼的嗜中性白血球形态结构差不多,胞核多为蚕豆形,很少见分叶核,分叶一般也只有二叶,这与哺乳类显然不同;嗜酸性白血球的形态结构与其他脊椎动物基本相似;在少数血涂片中看到了嗜碱性白血球。       

The parathyroid gland of the woodchuck (Marmota monax): a study of seasonal variations in the chief cells

The ultrastructure of the parathyroid chief cell in the woodchuck, Marmota monax, was studied during the four seasons of the year. Spring chief cells have stacks of granular endoplasmic reticulum, prominent multiple Golgi zones and many clumped mitochondria. Summer cells resemble those seen in the spring but the mitochondria are associated with stacks of granular endoplasmic reticulum. Multiple areas of stacked granular endoplasmic reticulum characterize the fall chief cells. Their Golgi zones are large and are associated with many dense core secretory granules. Lipoid vacuoles are frequently noted. Winter chief cells have secretory granules and phagolysosomes (dense bodies). Some of these cells contain stacked arrays of granular endoplasmic reticulum associated with mitochondria, others have only short segments. The above morphological findings are discussed in relation to those in other hibernators, the parafollicular (C) cell, and to the cyclic seasonal activities of the woodchuck.     

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.     

Ultrastructure of the liver cells in Salamandra salamandra (L.) in the end of Winter

Following hibernation, most salamander liver cells undergo alterations. The liver cells containing the structure of their active period present a normal nucleus, glycogen granules disseminated throughout the entire cytoplasm and granular mitochondria with several peripheral cristae. Most cells, however, possess altered mitochondria, transformed into electron-dense masses, or clear vesicles with the possibility of digesting the ambient organelles. Other cells have clear vacuoles with similar digestive possibilities. The endoplasmic reticulum is poorly represented in the liver cells that have suffered advanced alteration. The nucleus of these cells is homogeneously granular. The sytoplasm is populated by electron-dense bodies and lipid vacuoles. The nucleolemma and plasmalemma are thickened. The pigmented cells, altered concomitantly with the liver cells, contain granular aggregates. Some of the pigmented cells exhibit electron-clear formations similar to the reflecting platelets of the iridocytes of the integument of lower vertebrates.     

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.     

Effects of isoproterenol on the fine structure of the hamster parathyroid gland

Ultrastructural changes of the parathyroid glands of isoproterenol-treated golden hamsters were investigated. Many chief cells in the parathyroid glands after 5 and 10 minutes of administration of isoproterenol contain well-developed Golgi complexes and granular endoplasmic reticulum, numerous prosecretory granules, and many secretory granules in the peripheral cytoplasm as compared with the control animals. Many chief cells in the parathyroid glands after 1, 3, 6 and 12 hours of administration have poorly-developed Golgi complexes, granular endoplasmic reticulum, many secretory granules and numerous lipid droplets as compared with the control animals. The morphology of the parathyroid gland after 30 minutes and 24 hours of administration resembles that of the control animals. It is considered that isoproterenol affects the secretory activity of the parathyroid gland.     

Ultrastructural and cytochemical aspects of the basophilic cells in the hepatopancreas ofAplysia depilans(Mollusca, Opisthobranchia)

The basophilic cells ofAplysia depilanshave a pyramidal shape and a large nucleus usually located near the center or in the basal half of the cell. The nucleus possesses several clumps of condensed chromatin and a prominent nucleolus. The great profusion of rough endoplasmic reticulum cisterns in a major feature of these cells. Secretion granules are accumulated in the apical zone, and arylsulphatase was detected in some of them. In some basophilic cells a very substantial part of the cell volume was occupied by clear vacuoles, some of them reaching 9 mum. However, in other cells only a few vacuoles were observed. Probably the cells with just a few vacuoles are still young, and after a progressive accumulation, the vacuoles become abundant in old cells. The presence of a dark nucleus in the cells with a large number of vacuoles suggests that they are in a final stage of their life. Arylsulphatase was detected in the vacuoles and also in small secondary lysosomes containing substances in digestion. Bundles of tubules with 50 nm in diameter were found within some cisterns of rough endoplasmic reticulum. A cell fraction enriched in mannitol oxidase, extracted from the hepatopancreas of a terrestrial slug, consisted in very similar tubular structures. Using a histochemical method, mannitol oxidase was detected in the basophilic cells ofA. depilans, and it may be associated with the tubular structures of the endoplasmic reticulum. This is the first report of mannitol oxidase in opisthobranch molluscs. Almost spherical peroxisomes with a small nucleoid were abundant in these cells. The nucleoids presented a rectangular section, but a crystalline structure was not evident. The peroxisomes were stained after the cytochemical detection of catalase activity.     

Ultrastructure of the nuclear apparatus of the infusorian Loxodes magnus. I. The macronuclei, macronuclear anlagen and the interphasic micronuclei]

The nuclear apparatus of Loxodes magnus Stokes (Holotricha) consists of numerous macronuclei which belong to the diploid type and never divide, and of numerous micronuclei. No nuclear groups exist; individual nuclei often lie in cytoplasmic islets surrounded by large lacunae of the smooth endoplasmic reticulum. Interphasic micronuclei have two-membraned envelopes with numerous pores, usually lined at the cytoplasmic side with a layer of vacuoles, channels, or flattened vesicles of the smooth endoplasmic reticulum. The chromatin of the micronuclei consists of anastomosing threads, 0.1--0.2 mum wide, between which several nucleolus-like bodies of microfibrillar structure occur. Adult macronuclei have a similar nuclear envelope and a similar system of vacuoles, channels, and flattened agranular cisternae outside it. The macronucleus contains a single large composite nucleolus with 3 or 4 fibrillar cores inside the common granular cortex. The fibrillar cores are pierced by channels containing nucleolar organizers in the form of strands of condensed chromatin. The peripheral zone of the macronucleus is filled with decondensed chromatin fibrils and contains a number of small chromocenters and several aggregates of RNP granules. No protein inclusions (spheres) have been observed in Loxodes macronuclei. The macronuclear anlagen, developing in the cycle of every cell division, show progressive decondensation of the chromosomes and formation of several nucleoli, each with its own organizer. Later on, the nucleoli fuse into a single nucleolus. The small chromocentres are the last to form.     

Ultrastructure of spermiogenesis in the American alligator,Alligator mississippiensis (Reptilia,Crocodylia, Alligatoridae)

Testicular samples were collected to describe the ultrastructure of spermiogenisis in Alligator mississipiensis (American Alligator). Spermiogenesis commences with an acrosome vesicle forming from Golgi transport vesicles. An acrosome granule forms during vesicle contact with the nucleus, and remains posterior until mid to late elongation when it diffuses uniformly throughout the acrosomal lumen. The nucleus has uniform diffuse chromatin with small indices of heterochromatin, and the condensation of DNA is granular. The subacrosome space develops early, enlarges during elongation, and accumulates a thick layer of dark staining granules. Once the acrosome has completed its development, the nucleus of the early elongating spermatid becomes associated with the cell membrane flattening the acrosome vesicle on the apical surface of the nucleus, which aids in the migration of the acrosomal shoulders laterally. One endonuclear canal is present where the perforatorium resides. A prominent longitudinal manchette is associated with the nuclei of late elongating spermatids, and less numerous circular microtubules are observed close to the acrosome complex. The microtubule doublets of the midpiece axoneme are surrounded by a layer of dense staining granular material. The mitochondria of the midpiece abut the proximal centriole resulting in a very short neck region, and possess tubular cristae internally and concentric layers of cristae superficially. A fibrous sheath surrounds only the axoneme of the principal piece. Characters not previously described during spermiogenesis in any other amniote are observed and include (1) an endoplasmic reticulum cap during early acrosome development, (2) a concentric ring of endoplasmic reticulum around the nucleus of early to middle elongating spermatids, (3) a band of endoplasmic reticulum around the acrosome complex of late developing elongate spermatids, and (4) midpiece mitochondria that have both tubular and concentric layers of cristae. J. Morphol., 2010. © 2010 Wiley‐Liss, Inc.     

Development of male germ cells in the fur seal (Callorhinus ursinus)

Three types of spermatogonia have been distinguished in the fur seal: type A, intermediate, type B. The type A spermatogonia are presented by means of five varieties: stem A, A1, A2, A3, A4. The spermatogonia of the stem A type is characterized with presence of equally distributed chromatin in the nucleus. The spermatogonia of the A1-A4 types are characterized with a gradual condensation of chromatin. The intermediate spermatogonia possesses a light nucleus, chromatin as small and large granules is situated near the nuclear membrane. The spermatogonia of B1-B3 types have a round nucleus, their chromatin is granular. Spermatocytes both at the leptotene stage and at the zygotene stage are presented by means of three cellular forms. At the pachytene stage four cellular forms are distinguished. Basing on formation of the acrosomic apparatus, 18 stages of spermatids development are distinguished.     

Fine structure of the corpuscles of stannius in the toadfish.

The micro-anatomy of the corpuscles of Stannius of the toadfish, Opsanus tau, an aglomerular marine teleost, has been studied by light and electron microscopy. The corpuscles are composed of extensively anastomosed cords of epithelial cells which maintain intimate contact with blood capillaries. Most of the epithelial cells contain acidophilic granules which also show a positive reaction with the periodic acid-Schiff technique and aldehyde fuchsin. On the basis of fine structural criteria, three cell types can be recognized. The granular cells contain abundant quantities of granular endoplasmic reticulum, ribosomes, Golgi apparatus with prosecretory granules, coated vesicles, polymorphic mitochondria with lamellar cristae, filaments, microtubules, a cilium, a variety of lysosome-like dense bodies, glycogen particles, lipid droplets, secretory granules and intranuclear lipid-like inclusions. One variety of agranular cell (type I) is characterized by the total absence of secretory granules, but it contains large amounts of granular endoplasmic reticulum and ribosomes, conspicuous profiles of Golgi apparatus, coated vesicles and sometimes an abundance of glycogen. Another variety of agranular cell (type II) has poorly developed cytoplasmic organelles. The perivascular space between the capillary and parenchyma contains connective tissue cells and abundant nerve fibers. The different types of epithelial cells observed in the corpuscles of Stannius of this fish may represent functional stages of the secretory cycle in a single cell type.     

The ultrastructure of oogenesis and yolk formation in Labidocera aestiva (Copepoda: Calanoida)

Yolk formation in the oocytes of the free-living, marine copepod, Labidocera aestiva (order Calanoida) involves both autosynthetic and heterosynthetic processes. Three morphologically distinct forms of endogenous yolk are produced in the early vitellogenic stages. Type 1 yolk spheres are formed by the accumulation and fusion of dense granules within vesicular and lamellar cisternae of endoplasmic reticulum. A granular form of type 1 yolk, in which the dense granules within the cisternae of endoplasmic reticulum do not fuse, appears to be synthesized by the combined activity of endoplasmic reticulum and Golgi complexes. Type 2 yolk bodies subsequently appear in the ooplasm but their formation could not be attributed to any particular oocytic organelle. In the advanced stages of vitellogenesis, a single narrow layer of follicle cells becomes more developed and forms extensive interdigitations with the oocytes. Extra-oocytic yolk precursors appear to pass from the hemolymph into the follicle cells and subsequently into the oocytes via micropinocytosis. Pinocytotic vesicles fuse in the cortical ooplasm to form heterosynthetically derived type 3 yolk bodies.     

Comparative study of the ultrastructure of immune and normal phytohemagglutinin-treated lymphocytes]

Immune lymphocytes sorbed on the surface of the target cells were characterized during the period of the first three hours of combined incubation by the presence of the electron-dense matrix, abundance of mitochondria and lipids; small lymphocytes had disseminated ribosome organized into polysomes in the medium lymphocytes forming individual cysterns of the granular endoplasmic reticulum in the large lymphocytes, this indicating active protein synthesis by these cells. There were also revealed cells of plasmatic type. Cells incubated with the PHA for one hour represented a homogenous population of small lymphocytes of the same size as the clear cytoplasm containing free ribosomes and individual mitochondria. The proportion of the medium lymphocytes and the blasts increased with increase of the incubation period. These are cells with the clear cytoplasm freely disseminated polyribosomes in which no developed granular endoplasmic reticulum was sometimes revealed. The presence of two types of cells whose ultrastructure reflected their functional characteristics is discussed.     

冬季革胡子鲶中腺垂体细胞超微结构的研究

本文描述了冬季革胡子鲶中腺垂体ＧＴＨ细胞、ＴＳＨ细胞、ＳＴＨ细胞的超微结构。研究发现冬ＧＴＨ细胞呈现出６种不的结构类型,与生殖季节中的ＧＴＨ细胞在结构上很大的差异。本文进一步分析和讨论了冬季革胡子鲶中腺垂体ＧＴＨ、ＳＴＨ、ＴＳＨ细胞的结构变化及生理机能等问题。     

Ultrastructure of the haemocytes of Tetrodontophora bielanensis Waga (Collembola)

Five types of haemocytes: prohaemocytes, plasmatocytes, granular haemocytes, spherule cells and phagocytes, have been distinguished on the basis of ultrastructural studies. Prohaemocytes are ovoid cells with a simple structural organization. Plasmatocytes are larger; their cytoplasm contains well-developed rough endoplasmic reticulum, numerous mitochondria and free ribosomes. Granular haemocytes are the most numerous of the blood cells, characterized by the presence of electron-dense granules. The cytoplasm of spherule cells contains many spherules made up of filamentous material of medium electron density. Rough endoplasmic reticulum, free ribosomes and mitochondria are also found in the cytoplasm. Phagocytes are the largest haemocytes. Their cytoplasm contains an abundance of lysosomes and myelin structures. In addition to haemocytes, cells intermediate between plasmatocytes and granular haemocytes have been observed, which indicates that the granular haemocytes are derived from plasmatocytes.     

ULTRASTRUCTURAL STUDY ON THE SCLEROBLAST OF ORYZIAS LATIPES DURING ETHISTERONE-INDUCED ANAL-FIN PROCESS FORMATION

Cytodifferentiation of the scleroblast during ethisterone-induced anal-fin process formation in adult females of Oryzias latipes was observed electron-microscopically. Scleroblasts seem to arise from immature mesenchymal cells located not only along the postero-external margin of the joint plates, but also in the space between paired joint plates. These cells contained a small nucleus with condensed chromatin and a very small amount of cytoplasm with a marked paucity of formed organelles. These cells proliferated and/or migrated to the process-forming site of the joint plates and aggregated to the mass. Young scleroblasts were spindle-shaped in profile and contained an enlarged nucleus with dispersed chromatin. Rough-surfaced endoplasmic reticulum was developed in the cytoplasm. Scleroblasts became oval in shape and commenced to secrete bone matrix. Well-developed scleroblasts were characterized by an extensive development of rough-surfaced endoplasmic reticulum. This seems to correlate with the active protein synthesis required by the scleroblast for laying down bone matrix. As the young horny process developed, scleroblasts covered its apex, and became flattened. Some scleroblasts which became enclosed in the developing matrix had much the same characteristics as when they were lying on its surface.