On the fine structure of the electrocyte of Electrophorus electricus L.

Summary The general ultrastructure of the electrocyte, the basic unit of the electric organs of Electrophorus electricus, is analyzed. Presented herein are detailed observations of the syncytial surface, its fibrillar coat, invaginations of the plasma membrane and synaptic terminals. Using Thiéry's method glycogen granules were identified in the syncytial cytoplasm and inside the synaptic terminals, their size and structure being compatible with the muscular origin of the electric organs, to which the filamentous meshwork found in the cytoplasm may be related. Among the perinuclear-organelles, are dense bodies with crystalline patterns. The mitochondrial matrix contains dense granules, their size and structure varying according to the organ to which they belong and to the fixation method used.This work has been supported by Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq), Conselho de Ensino para Graduados da UFRJ and Banco Nacional de Desenvolvimento Econômico, FUNTEC-241     

Studies onSargassum

Summary Cytological comparisons of homologous tissues in blades and stipes by stereological analysis have shown differences exist between blade and stipe organs inSargassum. Based on measurements of total thylakoid and cristae membrane surface areas in these organs blades were found to contain 61% more thylakoid membrane surface and 65% more cristae membrane than stipes on a per unit volume basis. Assuming photosynthesis and respiration are directly related to the surface area of the internal membranes in the respective organelles it is possible to predict that blades will have a 61% greater photosynthetic and a 65% greater respiratory potential. Photosynthetic and respiratory rates for blades and stipes were determined manometrically and show a 62% greater photosynthetic and 59% greater respiratory rates for the blade tissues agreeing very well with predicted values.Present evidence indicates that photosynthetic and respiratory rate differences observed in the blades and stipes inSargassum are the result of increased membrane surface areas in the larger cells of the tissues which make up the blade. The basic cell structure,i.e., the percent volume of cell cytoplasm occupied by each organelle, is similar in homologous tissues of both organs regardless of cell size. Therefore physiological differences between the two organs are primarily due to changes in cell size and not in basic cell construction. This provides an interesting mechanism for producing physiological differences without changing basic cell structure in the organs of this plant.     

Fine structure of developing polyphosphate bodies in a blue-green alga,Plectonema boryanum

Summary Stages in the development of polyphosphate bodies in the blue-green alga, Plectonema boryanum, grown under continuous illumination in the presence of excess phosphate, are reported. During the first stage, an electronlucent area appears near the nucleoplasm or cross walls; it gradually increases to a size approximately equal to that of the final polyphosphate body. In this area a porous structure of medium electron density develops, while simultaneously electron-dense material, interpreted as polyphosphate, is deposited in the adjacent cytoplasm. Eventually, this material seems to penetrate into the porous structure. When the polyphosphate bodies are fully formed, the surrounding cytoplasm does not contain detectable amounts of polyphosphate.The formation of polyphosphate bodies in P. boryanum is compared with that in some bacterial species.     

The nephridia of the interstitial polychaete Hesionides arenaria and their phylogenetic significance (Polychaeta,Hesionidae)

Summary The small hesionid polychaete Hesionides arenaria possesses paired segmental excretory organs that closely resemble solenocytic protonephridia. The nephridium consists of one terminal cell and four tubule cells which form the emission channel. From the terminal cell, up to six flagella arise each surrounded by a weir of ten regularly arranged cytoplasmic rods. The structure of the cytoplasm of three of the following cells suggests that they function in active transport and storage. Because all of the larger, more primitive species of this family are equipped with metanephridia, the possibility is discussed that these organs have been developed out of metanephridia. The Hesionides arenaria nephridium may be a morphological stage in the evolutionary pathway from metanephridia to solenocytes. This would mean that solenocytes can no longer be considered to be homologous in every case with other protonephridial organs in polychaetes and may well be derived several times independently out of metanephridia or true protonephridia.     

The mandibular organ of the female spider crab,Libinia emarginata,in immature,mature, and ovigerous crabs

The cells of mandibular organs of female Libinia emarginata exhibit changes in substructure during molting and vitellogenesis. The cytoplasm is that of a steroid-hormone producing cell. The cells do not appear to produce ecdysones.     

Fine structural and histochemical study of lingual taste organs of Rana catesbeiana (Anura: Ranidae) transplanted to liver

Autologous tongues were transplanted onto the liver of the anuran Rana catesbeiana, specimens of which were sacrificed at intervals from 6 hr to 5 months after transplantation. Light and electron microscopy as well as histochemistry disclose that the grafts start to organize into cysts after 14 days. The taste organs occur in all grafts irrespective of the age of the graft. All surviving taste organs exhibit intense adenosine triphosphatase (ATPase) activity and contain fluorescent basal cells of the usual type. Ultrastructurally, the taste organs are composed of three distinct types of cells that lack nerves. The taste and basal cells retain the characteristic dense-core granules in their cytoplasm through the experimental periods. The present results suggested that the taste organs of Rana can survive ectopically in the liver for up to 5 months.     

The male reproductive system of Costelytra zealandica (White)(Coleoptera: Scarabaeidae: Melolonthinae)

Abstract

The morphology and histology of the male internal reproductive organs of Costelytra zealandica show many similarities to other Scarabaeoidae, and are particularly close to other Melolonthinae and to Rutelinae. Testes follicles of C. zealandica have the usual structure for Melolonthinae with basal lobes surrounding the ends of the vasa efferentia. Epithelial cells of the vasa efferentia, vasa deferentia, and vesiculae seminales have similar densely basophilic cytoplasm but muscle layers are best developed around the latter. Accessory glands lack muscle and are not differentiated histologically into regions but do differ from their reservoirs. The ejaculatory duct has a cuticular intima and is differentiated into anterior and posterior regions. Both are surrounded by a muscular sheath which expands in the posterior region to enclose fluid. This forms a hydraulic mechanism for everting the internal sac during intromission. The parameres hook into the female’s genital chamber during copulation and have no pincer action. Probable homologies are listed between muscles of the external genitalia and anus of C. zealandica and other Scarabaeoidea.     

PYRENOIDS,RAPHES, AND OTHER FINE STRUCTURE IN DIATOMS

Pyrenoids of 6 diatoms, Acnanthes minutissima, Cyclotella meneghiniania, Cymbella affinis, Gomphonema parvulum, Nitzschia sp., and Surirella ovalis, were examined comparatively with the electron microscope. All except those of G. parvulum were membrane-limited. The pyrenoid membrane forms a ridge around the pyrenoid of S. ovalis, C. meneghiniania, and Nitzschia sp. Distended double-disc bands cross the pyrenoids of C. affinis, G. parvulum, S. ovalis, and A. minutissima; single-disc bands occur in C. meneghiniania, and 3 disc bands in Nitzschia sp. The raphe fissures of A. minutissima, Nitzschia sp., and S. ovalis did not contain any cytoplasm or obvious organs of locomotion. In G. parvulum, membranous profiles extend outward from the raphe fissure, but these probably are not responsible for movement. In this diatom 2 membranes usually cross the raphe, and the distance between them fluctuates indicating that they may undulate to force water through the raphe. A 7–10 mμ subfrustular zone is associated with the inner surface of the silica, but separate from the cytoplasmic membrane, in Nitzschia sp. and G. parvulum. In the latter, it is attached to siliceous knobs protruding from the inner surface of the silica. It may join the 2 halves of the frustale, which are otherwise not connected either to each other or to the cytoplasm. Pores 80–100 mμ in diameter occur in the nuclear envelopes of all diatoms examined. Dictyosomes are always perinuclear. In S. ovalis the vesicular complex is a convoluted, single-membrane-limited structure containing a variety of vesicular profiles, and occupying much of the central cytoplasm. Internally it resembles leucosin bodies of a chrysophyte, but the arrangement and morphology of the internal vesicles suggests that intracellular pinocytosis may occur.     

Ultrastructure of nuchal organs in some marine polychaetes

Polychaetes normally possess one pair of nuchal organs at the posterior edge of the prostomium or peristomium. They have been regarded as chemosensory organs. The nuchal organs of four marine polychaete species with different habits were investigated by electron microscopy. Although the shapes of nuchal organs can vary greatly from simple ciliary bands (Scolelepis squamata, Spionidae) to retractile tongue-like, piston- or finger-shaped forms (Eteone longa, Anaitides mucosa, Phyllodocidae; Heteromastus filiformis, Capitellidae), the structural components, including the ciliated supporting cells, sensory cells, and nuchal epidermal cells, are essentially similar. The differences basically concern 1) the position of the sensory cells with relation to the ciliated supporting cells, 2) the location and structure of the nuchal nerve, and 3) the structure of the nuchal cuticle. The diverging nature of this modified cuticle is described and discussed in detail. Comparisons are made with the fine structure of nuchal organs of other polychaete species. Similarities of cellular components of nuchal organs are found not only in the four species studied here but also in all nuchal organs investigated so far. This is hypothesized to be due to the fact that the polychaete stem species already possessed nuchal organs with the respective cell types. Differences in the number and distribution of cellular components and in the overall shape of nuchal organs are thought to have evolved in correlation with the equipment of other cephalic appendages and with different habits and modes of nutrition.     

A Comparative Study of Gametocyte Ultrastructure in Avian Haemosporidia*

The fine structure of gametocytes of 3 avian haemosporidian parasites Plasmodium gallinaceum, Haemoproteus columbae, and Leucocytozoon simondi has been studied and compared by electron microscopy. The gametocytes of all 3 species are bounded by a 3-layered limiting membrane system, possess a cytostome during some portion of their residence within host cells, and their sex can be distinguished by both nuclear and cytoplasmic characteristics. L. simondi differs most significantly from P. gallinaceum and H. columbae in possessing large intranuclear granules, mitochondria associated with pocket infoldings of the nuclear envelope near the atypical centriole complex and compartmentalization of the cytoplasm by segments of closely aligned unit membranes. Further, the cytostome of L. simondi does not appear to be a persistent structure as in the other 2 species and pigment is not present within food vacuoles. L. simondi also is capable of infecting a wider variety of host cells and within leukocytes produces striations of the host nucleus and an apparent spiral banding of the host cell surface. The comparison of P. gallinaceum, H. columbae, and L. simondi gametocytes by electron microscopy leads to the conclusion that Plasmodium and Haemoproteus are more closely related to each other than either of them is on Leucocytozoon. The terminology used to describe certain organelles within the gametocyte's cytoplasm has been reexamined and the relationship of the nucleolus to parasite maturation also is described.     

竹亚科单枝竹属芸香竹花枝和花特征补充描述

繁殖器官在竹类植物的分类学研究中具有重要意义,研究组在广西马山县观察到竹亚科单枝竹属芸香竹正在开花,该文根据观察到的开花状况和采集到的标本解剖观察结果,对其花枝和繁殖器官特征做了详细的中文及拉丁文补充描述。经对比芸香竹与属内已知繁殖器官结构的单枝竹和小花单枝竹的繁殖器官,3个竹种有相同的繁殖器官结构特征,但在小花数目和大小等方面具有差异。繁殖器官比较表明该属竹种的繁殖器官对喀斯特地貌环境有特殊的适应性,也支持依据营养器官差异划分为3个独立竹种。     

Special cutaneous receptor organs of fish. IV. Ampullary organs of the nonelectric catfish, Kryptopterus

Ampullary organs of the transparent catfish, Kryptopterus bicirrhus, are present in large numbers on the head and in a regular pattern of lines on the body and fins. The organs lie in the epidermis, and have a pore that opens to the surface. Flattened cells form a roof and walls. On the floor of the organ there are a “sensory hillock,” composed of spherical receptor cells and columnar supporting cells, and a “secretory hillock” composed of columnar secretory cells. The receptor cells are nonciliated and have only afferent innervation. The organ cavity is filled with jelly. The organs are compared with ampullary organs of the weakly electric fish Eigenmannia, ampullae of Lorenzini of Raja, and small pit organs of Amiurus. Structural characteristics of the ampullary organs of Kryptopterus make them especially suitable for electrophysiological studies.     

Anatomy and ultrastructure of ventral pharyngeal organs and their phylogenetic importance in Polychaeta (Annelida)

Summary Transmission electron microscopic studies were carried out on the ventral pharyngeal organs in Ctenodrilus serratus and Scoloplos armiger. The pharyngeal organs are composed of a muscle bulbus and a tongue-like organ. In both species the muscle bulbus consists of transverse muscle fibres and interstitial cells with voluminous cell bodies and dorsoventral tonofilaments; the investing muscle runs into the tongue-like organ; the nuclei of the investing muscle fibres are located in caudal bulges; salivary glands are not present, but numerous gland cells occur in the bulbus epithelium. The tongue-like organ, however, is formed by lateral folds (C. serratus) or a bridge-like structure (S. armiger). The specific structure of the bulbus muscle is probably a homologous characteristic also occurring in several other polychaete families. The phylogenetic importance of this ventral pharynx is discussed and a hypothesis is suggested to explain the differentiation of certain other ventral pharyngeal organs from this probably primitive type.     

The Fine Structure of Haemoproteus columbae Sporozoites*

SYNOPSIS. The fine structure of Haemoproteus columbae sporozoites has been studied and compared to sporozoite structure as revealed by the light microscope. The sporozoites are ultrastructurally similar to those of other Haemosporidia in that they possess a 3-layered pellicle, subpellicular microtubules, polar ring, micropore, free ribosome-like particles, micronemes, a structure resembling a Golgi complex, an irregular mitochondrion, and a large nucleus. In the anterior region of the sporozoite there are 21–22 regularly arranged longitudinal subpellicular microtubules located peripherally around the cell. In the apical region the microtubules appear thickened on 1 side. The sporozoite of H. columbae has a microneme system in which 1–3 micronemes are associated with the outer pellicular membrane at the anterior end. Micronemes are found throughout the cytoplasm, but occur in greater concentration in the anterior region of the sporozoite. A clear pellicular cavity, located between the polar ring and the termination of the inner pellicular layer, is present at the anterior end of the sporozoite. Vesicular invaginations of the inner pellicular layer have been observed in the anterior region; their function is unknown. Spherical osmophilic bodies are found throughout the cytoplasm.     

The ultrastructure of germinal beds in the ovary of Gerrhonotus coeruleus (Reptilia: Anguidae)

A study of ovarian structure in adult Alligator Lizards (Gerrhonotus coeruleus) was conducted by light microscopy and transmission electron microscopy. Particular attention was directed to characterizing the ultrastructure of germ-line cells, prior to follicle formation. General ovarian structure in this lizard is similar to that of other lizards. The paired organs are hollow, thin-walled sacs containing follicles in roughly 3 to 4 size classes. Ovarian germinal tissue consists of oogonia (diploid cells which divide mitotically) and oocytes (meiotic cells), intermixed with ovarian surface epithelial cells. Germ cells reside in two dorsal patches of epithelium per ovary (germinal beds), as is common in lizards. Oogonia in interphase show a highly dispersed chromatin pattern. Within oogonia cytoplasm, Golgi complexes are scarce, rough endoplasmic reticulum is absent, and lipid droplets are rare. Ribosomes are scattered in small clusters. Small, round vesicles are common in all oogonia; glycogen-like granules are present in some. Mitochondria form a juxtanuclear mass within which groups of several mitochondria surround a dense granule. “Nuage” granules also are found unassociated with mitochondria. Oocytes are present in stages of meiotic prophase up to diplotene. Synaptinemal complexes are seen in several (pachytene) cells. The cytoplasm of oocytes differs from that of oogonia in that mitochondria do not form groups, and nuage and glycogen are absent, whereas small round vesicles and large irregular vesicles are common. The ultrastructural similarities in germ cells of a reptile as compared to those of other vertebrates strengthens the notion that germ-line cells possess (or lack) qualities related to the undifferentiated state of these cells.     

Fine structure and absorption of ferritin in the digestive organs of Loligo vulgaris and L. Forbesi (Cephalopoda,Teuthoidea)

The digestive organs possibly involved in food absorption in Loligo vulgaris and L. forbesi are the caecum, the intestine, the digestive gland, and the digestive duct appendages. The histology and the fine structure showed that the ciliated organ, the caecal sac, and the intestine are lined with a ciliated epithelium. The ciliary rootlets are particularly well developed in the ciliated organ, apparently in relation to its function of particle collection. Mucous cells are present in the ciliated organ and the intestine. Histologically, the digestive gland appears rather different from that of other cephalopods. However, the fine structure of individual types of squid digestive cell is actually similar to that of comparable organs in other species, and the squid cells undergo the same stages of activity. Digestive cells have a brush border of microvilli, and numerous vacuoles, which sometimes contain “brown bodies.” However, no “boules” (conspicuous protein inclusions of digestive cells in other species) could be identified in their cytoplasm; instead only secretory granules are present. In the digestive duct appendages, numerous membrane infoldings associated with mitochondria are characteristic features of the epithelial cells in all cephalopods. Two unusual features were observed in Loligo: first, the large size of the lipid inclusions in the digestive gland, in the caecal sac, and in the digestive duct appendages; and second, the large number of conspicuous mitochondria with well-developed tubular cristae. When injected into the caecal sac, ferritin molecules can reach the digestive gland and the digestive duct appendages via the digestive ducts, and they are taken up by endocytosis in the digestive cells. Thus, it appears that the digestive gland of Loligo can act as an absorptive organ as it does in other cephalopods.     

Structure,expression profile and subcellular localisation of four different sucrose synthase genes from barley

Genes encoding two new isoforms of sucrose synthase from barley, HvSs3 and HvSs4, have been characterised and their expression patterns compared with those previously described for HvSs1 and HvSs2, in different organs and during seed maturation and germination. Their response to several abiotic stimuli has also been investigated in leaves: HvSs1 is up-regulated by anoxia and HvSs3 by water deprivation while no response is observed to 150 mM NaCl treatment; HvSs1 and HvSs3 are also induced by cold temperatures. Using translational fusions and transient expression analyses, the four isozymes have been localised not only to the cytoplasm but also along several cytoplasmic tracks and at the inner side of the cell membrane; besides, HvSS1 is also associated with mitochondria, a localisation that has been predicted in silico with the TargetP and Predotar programmes. These data suggest distinct although partially overlapping roles, for the four barley sucrose synthase isoforms, in the channelling of carbon towards different metabolic pathways within the cell.     

Elektronenmikroskopische Untersuchungen zum Problem der Sekretion der bindegewebigen Interzellularsubstanz

Zusammenfassung Die Sinnesorgane des Vorderendes von Linens ruber werden elektronen-mikroskopisch vor allem im Hinblick auf die rezeptorischen Strukturen untersucht. Am Kopfvorderrand liegen zwei Rezeptortypen: Typ 1 ist mit 20–40, Typ 2 nur mit einer Zilie besetzt. Die Seitenwurzeln der Zilien von Typ 1 sind parallel angeordnet. Die Perikarya beider Rezeptoren liegen unterhalb des Epithelverbandes, dessen Großteil von Typ 1 eingenommen wird. In den Kopfspalten finden sich primäre Sinneszellen mit eingesenkten Zilien, deren Membran regelmäßig aufgeschwollen ist. Im Cerebralorgan dominiert ebenfalls eine primäre Sinneszelle, die reichlich efferent innerviert wird. In den Lichtrezeptoren findet sich eine Zilie unter dem distalen Mikrovillisaum.Alle beschriebenen Zilien sind deutlich voneinander und von den Wimpern der Epidermis unterschieden. Sie werden mit den Zilien der Rezeptoren anderer Tiergruppen verglichen.

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The fine structure of the sensory organs of Lineus ruber O. F. Müller (Nemertini, Heteronemertini)

Summary The sensory organs located in the head reagion of the ribbon worm Lineus ruber have been investigated with the electron microscope. Attention has been focussed on the apical cell-structures, which are assumed to be related to sensory functions. At the anterior edge of the head two receptor-types occur: type 1 bears 20–40 apical cilia, type 2 only 1 cilium per cell. The lateral ciliary rootlets of type 1 are oriented strictly parallel. The pericarya of both receptor types of which type 1 is particularly dominant, are situated below the basement lamina of the epithelium. In the cephalic clefts primary sensory cells occur, the cilia of which are invaginated into the apical cytoplasm. Their ciliary membrane exhibits regular inflations. In the cerebral organ also primary sensory cells dominate which receive an abundant efferent nerve supply. In the light receptors only one cilium is to be found below the distal villi. The cilia of the sensory cells and also of the ordinary epidermis cells show individual characteristics not shared by the other types. Their structural peculiarities are compared with those of sensory organs of other groups of animals.

Herrn Prof. Dr. Drs. h. c. W. Bargmann zum 65. Geburtstag gewidmet.     

Ultrastructural investigation of the nuchal organs of Pygospio elegans (Polychaeta)

Summary The differentiation of the dorsal organs as well as the structure of the nuchal organs and their relation to the central nervous system in adult Pygospio elegans were studied by electron microscopy and compared to the nuchal organs of the larvae. The nuchal organs are represented by paired ciliary bands on the dorsal side of the first setiger, delimiting a median caruncle that is completely filled with epidermal and nervous tissue. They are composed of ciliated supporting cells and bipolar primary sensory cells constituting the nuchal ganglia, which are integrated into the brain. Microvillus-like processes of the ciliated cells give rise to a secondary covering layer over the sensory epithelium. The size of the nuchal organs is a sexually dimorphic feature.Dorsal organ formation is concomitant with the onset of sexual maturation in the male sex only. They appear as metameric ciliary bands on the dorsal side of the anterior body region and consist of ciliated cells accompanied by lateral accumulations of tubular gland cells. In the gametogenic segments they are structurally associated with the male genital pores and may be involved in reproduction. The results refute previous theories that dorsal organs are sensory and have a common origin to nuchal organs.Abbreviations ac anterior commissure of the brain - ace anterior circumesophageal connective - bb basal body - bl basal lamina - c cuticle - ca caruncle - cc ciliated cell - ci sensory cilium - co microvillar cover - d septate desmosome - db dorsal blood vessel - dn dorsal nerve cord - ea efferent axons - ec epidermal cell - eg elementary granules - g Golgi complex - i filamentous inclusion - lm longitudinal muscles - ly lysosome - mc motile cilia - mv microvillus - n neuron - ng nuchal ganglion - nn nuchal nerve - nu nucleus - oc olfactory chamber - pa palp - pc posterior commissure of the brain - pce posterior circumesophageal connective - rer rough endoplasmic reticulum - sI setiger I - sb sensory bulb - sc sensory cell - sd sensory dendrite - ser smooth endoplasmic reticulum - tf tonofilament bundle - v clear vesicles - za zonula adherens