scholarly journals The structure of nectary of Platanthera bifolia L. Orchidaceae

2014 ◽  
Vol 66 (1) ◽  
pp. 5-11 ◽  
Author(s):  
Małgorzata Stpiczyńska
Keyword(s):  
Endoplasmic Reticulum ◽  
Golgi Apparatus ◽  
Secretory Cells ◽  
Floral Nectary ◽  
Secretory Tissue ◽  
Characteristic Features ◽  
Anatomy And Ultrastructure

The anatomy and ultrastructure of floral nectary of <em>Platanthera bifolia</em> were studied. The epidermis inside the nectary spur showed characteristic features of secretory tissue. Many cells of this epidermis were protruded forming unicellular hairs. The protoplasts of secretory cells were characterized by few small vacuoles, a lot of mitochondria and leucoplasts, which stored starch before secretion. Numerous vesicles budded off from the endoplasmic reticulum and the Golgi apparatus were accumulated near plasmalemma and fused with it. This fact probably indicates that these structures are involved in secretory processes. Nectar was released onto the surface through the pores in a ruptured cuticle, which covered the walls of secretory hairs.

scholarly journals The structure of the spur nectary in Dendrobium finisterrae Schltr. (Dendrobiinae, Orchidaceae)

2012 ◽  
Vol 64 (1) ◽  
pp. 19-26 ◽  
Author(s):  
Magdalena Kamińska ◽  
Małgorzata Stpiczyńska
Keyword(s):  
Electron Microscopy ◽  
Cell Walls ◽  
Single Layer ◽  
Secretory Cells ◽  
Vascular Bundles ◽  
Nectar Guides ◽  
Floral Nectary ◽  
Transmission Electron ◽  
Secretory Tissue ◽  
The One

To date, the structure of the nectary spur of <i>Dendrobium finisterrae</i> has not been studied in detail, and the present paper compares the structural organization of the floral nectary in this species with the spurs of other taxa. The nectary spur of <i>D. finisterrae</i> was examined by means of light microscopy (LM), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). It is composed of a single layer of secretory epidermis and several layers of small and compactly arranged subepidermal secretory cells. The secretory cells have thick cellulosic cell walls with primary pits. The secretory tissue is supplied by vascular bundles that run beneath in ground parenchyma and are additionally surrounded by strands of sclerenchymatous fibers. The flowers of the investigated species displayed morphological features characteristic of bee-pollinated taxa, as they are zygomorphic, creamy-green coloured with evident nectar guides. They also emit a weak but nice scent. However, they possess some characters attributed to bird-pollinated flowers such as a short, massive nectary spur and collenchymatous secretory tissue that closely resembles the one found in the nectaries of certain species that are thought to be bird-pollinated. This similarity in anatomical organization of the nectary, regardless of geographical distribution and phylogeny, strongly indicates convergence and appears to be related to pollinator-driven selection.

Nectary structure and nectar presentation in the Mediterranean geophyte, Urginea maritima (Hyacinthaceae)

Botany ◽  
2008 ◽  
Vol 86 (10) ◽  
pp. 1194-1204 ◽  
Author(s):  
Sharaf Al-Tardeh ◽  
Thomas Sawidis ◽  
Barbara-Evelin Diannelidis ◽  
Stylianos Delivopoulos
Keyword(s):  
Intermediate Stage ◽  
Secretory Cells ◽  
Urginea Maritima ◽  
Floral Nectary ◽  
Hydrolysis Process ◽  
Septal Nectary ◽  
Parenchyma Cells ◽  
Subsidiary Cells ◽  
Hydrolysis Of ◽  
Anatomy And Ultrastructure

The morphology, anatomy, and ultrastructure of the floral nectary of Urginea maritima (L.) Baker were investigated at three stages of nectary development. The plant possesses a typical gynopleural (septal) nectary with secondary presentation. The nectary consists of one layer of epithelium secretory cells and one to four layers of subsidiary cells subtended by two to six layers of parenchyma (subnectary) cells. The nectary releases the nectar at a point two-thirds towards the summit of the ovary by means of carpellary sutures. Nectar secretion appears to depend largely on the hydrolysis of starch grains stored in amyloplasts at the intermediate stage. The hydrolysis process most likely commences in the epithelium layer followed by the subsidiary tissue and then the parenchyma cells of the ovary wall. A symplastic transfer of the secreted nectar occurs by plasmodesmata connecting the subsidiary cells to the parenchyma and the epithelial secretory cells. However, microchannels in the cell wall of the epithelial cells may facilitate the apoplastic transfer of the nectar into the nectary cavity. The old stage of nectary development is characterized by a crystallized form of nectar, collapse of the parenchyma cells, complete starch hydrolysis, and disappearance of the amyloplasts and endoplasmic reticulum.

scholarly journals THE ULTRASTRUCTURE OF AMELOBLASTS DURING MATRIX FORMATION AND THE MATURATION OF ENAMEL

1961 ◽  
Vol 9 (4) ◽  
pp. 825-839 ◽  
Author(s):  
Edward J. Reith
Keyword(s):  
Endoplasmic Reticulum ◽  
Electron Microscope ◽  
Golgi Apparatus ◽  
Intercellular Space ◽  
Transitional Zone ◽  
Secretory Cells ◽  
Perinuclear Space

Ameloblasts from different regions of upper incisors of rats were examined with the electron microscope. During matrix formation, the cells resemble secretory cells. They are extremely long, tightly packed, and show considerable polarity. Nuclei are at the basal end of the cell. Mitochondria are proximal and the Golgi apparatus distal to the nucleus. Ergastoplasm is found in all levels but mainly in the distal end. A terminal bar apparatus separates the distal end of the cell from Tomes's process. Next to this is soft enamel. The next incisal region is a transitional zone in which the ameloblasts separate easily from the enamel. Endoplasmic reticulum is dilated and very obviously in communication with the perinuclear space. Mitochondria are present not only proximal, but also distal, to the nucleus. The next incisal zone consists of cells related to the maturation of enamel. They no longer resemble secretory cells, but now have more characteristics of transporting cells. Processes from the distal end of the cell are present with mitochondria closely applied to the base of the processes. A considerable amount of intercellular space exists with microvilli projecting into the space. Iron granules appear in these cells, and the ergastoplasmic cisternae are dilated. In the incisal end of this zone, the iron granules form aggregates. The iron finally leaves the cells to enter the enamel. Free RNP particles and fibrils become more evident after the iron leaves the cells. In the most incisal region, the ameloblasts are further reduced in height. Distal processes are no longer present and fibrils are more conspicuous.

scholarly journals Control of venom production and secretion by sympathetic outflow in the snake Bothrops jararaca.

1997 ◽  
Vol 200 (19) ◽  
pp. 2547-2556 ◽  
Author(s):  
N Yamanouye ◽  
L R Britto ◽  
S M Carneiro ◽  
R P Markus
Keyword(s):  
Endoplasmic Reticulum ◽  
Nervous System ◽  
Golgi Apparatus ◽  
Sympathetic Nervous System ◽  
Rough Endoplasmic Reticulum ◽  
Synthetic Activity ◽  
Secretory Cells ◽  
Bothrops Jararaca ◽  
Venom Glands ◽  
Sympathetic Nervous

Many studies have examined the morphological and biochemical changes in the secretory epithelium of snake venom glands after a bite or milking. However, the mechanisms of venom production and secretion are not yet well understood. The present study was undertaken to evaluate the role of the sympathetic nervous system in the control of venom production and secretion. Venom glands were obtained from Bothrops jararaca (Viperidae) snakes, either unmilked previously or milked 4, 7 or 15 days before they were killed. Levels of tyrosine-hydroxylase-like immunoreactivity were higher in venom glands collected 4 days after milking, coinciding with the maximal synthetic activity of the secretory cells. The only catecholamine detected by high-performance liquid chromatography was noradrenaline, indicating the presence of noradrenergic fibres in these glands. In reserpine-treated milked snakes, no venom could be collected, and electron microscopic analysis showed narrow rough endoplasmic reticulum cisternae, instead of wide cisternae, and less well-developed Golgi apparatus compared with milked untreated snakes, indicating impairment of protein synthesis and secretion. The administration of isoprenaline or phenylephrine (beta- and alpha-adrenoceptor agonists, respectively) to reserpine-treated milked snakes promoted the widening of the rough endoplasmic reticulum and restored venom production, but only phenylephrine restored the development of the Golgi apparatus and the formation of many secretory vesicles. These results provide the first evidence that the sympathetic nervous system plays an important role in venom production and secretion in the venom glands of Bothrops jararaca. Understanding the importance of noradrenergic stimulation in venom production may provide new insights for research into the treatment of snakebites.

scholarly journals Anatomy and ultrastructure of floral nectary of lnula helenium L (Asteraceae)

2011 ◽  
Vol 76 (3) ◽  
pp. 201-207 ◽  
Author(s):  
Aneta Sulborska ◽  
Elżbieta Weryszko-Chmielewska
Keyword(s):  
Secretory Cells ◽  
Secretory Vesicles ◽  
Nectar Secretion ◽  
Golgi Bodies ◽  
Floral Nectary ◽  
Granular Cytoplasm ◽  
Inula Helenium ◽  
Modified Stomata ◽  
Floral Nectaries ◽  
Anatomy And Ultrastructure

Floral nectaries of <em>Inula helenium</em> L. only occurred in disc florets and were situated above the inferior ovary. The shape of the investigated glands (five-armed star with rounded tips and deep incisions - observed from above) clearly differed from the shape of the nectaries of other <em>Asteraceae</em>, also the height of nectary was much lower (129 µm). The glandular tissue of the nectaries of elecampane was composed of a single-layered epidermis and 5--9 layers of secretory cells. Nectar was released through modified stomata, mainly arranged in the top part of the gland. The secretory cells were characterised by granular cytoplasm and the presence of a large, often lobate, cell nucleus. In the cytosol, numerous amoeboid plastids, mitochondria, Golgi bodies and ribosomes were present. In small vacuoles, myelin-like structures, fibrous material and vesicles with the content of substances which can be secretion, were observed. The plastid stroma showed different electron density and the presence of internal tubules and plastoglobules. Vesicular extensions forming bright zones were visible between the membranes of the nuclear envelope. Adjacent to the plasmalemma, as well as between the plasmalemma and the cell wall, secretory vesicles occurred, indicating the granulocrine mechanism of nectar secretion.

Golgi Apparatus and Melanogenesis: Ultrastructural Study of a Human Cellular Blue Nevus (Melanocytoma)

1973 ◽  
Vol 31 ◽  
pp. 380-381
Author(s):  
S.R. Allegra
Keyword(s):  
Endoplasmic Reticulum ◽  
Golgi Apparatus ◽  
Ultrastructural Study ◽  
The Other ◽  
Blue Nevus ◽  
Normal Complement ◽  
Golgi Vesicles ◽  
Golgi System ◽  
The Subject ◽  
Cellular Blue Nevus

The respective roles of the ribo somes, endoplasmic reticulum, Golgi apparatus and perhaps nucleus in the synthesis and maturation of melanosomes is still the subject of some controversy. While the early melanosomes (premelanosomes) have been frequently demonstrated to originate as Golgi vesicles, it is undeniable that these structures can be formed in cells in which Golgi system is not found. This report was prompted by the findings in an essentially amelanotic human cellular blue nevus (melanocytoma) of two distinct lines of melanocytes one of which was devoid of any trace of Golgi apparatus while the other had normal complement of this organelle.

Analysis of the Anterior Secretory Cells of Onchidohs Muricata (Nudibranchia)

1981 ◽  
Vol 39 ◽  
pp. 614-615
Author(s):  
Roy Skidmore
Keyword(s):  
Endoplasmic Reticulum ◽  
Secretory Granules ◽  
Golgi Body ◽  
The Body ◽  
Secretory Cells ◽  
Secretory Vesicles ◽  
High Magnification ◽  
Large Numbers ◽  
Membrane Bound ◽  
Sole Of The Foot

The long-necked secretory cells in Onchidoris muricata are distributed in the anterior sole of the foot. These cells are interspersed among ciliated columnar and conical cells as well as short-necked secretory gland cells. The long-necked cells contribute a significant amount of mucoid materials to the slime on which the nudibranch travels. The body of these cells is found in the subepidermal tissues. A long process extends across the basal lamina and in between cells of the epidermis to the surface of the foot. The secretory granules travel along the process and their contents are expelled by exocytosis at the foot surface.The contents of the cell body include the nucleus, some endoplasmic reticulum, and an extensive Golgi body with large numbers of secretory vesicles (Fig. 1). The secretory vesicles are membrane bound and contain a fibrillar matrix. At high magnification the similarity of the contents in the Golgi saccules and the secretory vesicles becomes apparent (Fig. 2).

Spermatogenesis in the Dragonfly with Particular Reference to the Cytoplasmic Organelles

1972 ◽  
Vol 30 ◽  
pp. 110-111
Author(s):  
Sant S. Sekhon
Keyword(s):  
Endoplasmic Reticulum ◽  
Golgi Apparatus ◽  
Mature Sperm ◽  
Electron Microscopic ◽  
Cytoplasmic Organelles ◽  
Microscopic Studies ◽  
Insect Sperm ◽  
Large Round

Although there have been numerous studies concerning the morphogenetic changes accompanying the maturation of insect sperm, only a few deal with the sperm differentiation in the dragonflies. In two recent electron microscopic studies Kessel, has comprehensively treated the erlationship of microtubules to the nucleus and mid-piece structures during spermiogenesis in the dragonfly. The purpose of this study is to follow the sequential nuclear and cytoplasmic changes which accompany the differentiation of spermatogonium into a mature sperm during spermatogenesis in the dragonfly (Aeschna sp.).The dragonfly spermatogonia are characterized by large round nuclei. Loosely organized chromatin is usually unevenly distributed within the spermatogonial nuclei. The scant cytoplasm surrounding the nucleus contains mitochondria, the Golgi apparatus, elements of endoplasmic reticulum and numerous ribosomes (Fig. 1).

An Ultra-Structural Study of Human Melanoma in Vivo and Vitro

1976 ◽  
Vol 34 ◽  
pp. 258-259
Author(s):  
James R. Gaylor ◽  
Fredda Schafer ◽  
Robert E. Nordquist
Keyword(s):  
Endoplasmic Reticulum ◽  
Golgi Apparatus ◽  
Protein Aggregation ◽  
Structural Study ◽  
Human Melanoma ◽  
Protein Matrix ◽  
Early Form ◽  
Endoplasmic Reticulum Protein ◽  
Mitochondrial Origin

Several theories on the origin of the melanosome exist. These include the Golgi origin theory, in which a tyrosinase-rich protein is "packaged" by the Golgi apparatus, thus forming the early form of the melanosome. A second theory postulates a mitochondrial origin of melanosomes. Its author contends that the melanosome is a modified mitochondria which acquires melanin during its development. A third theory states that a pre-melanosome is formed in the smooth or rough endoplasmic reticulum. Protein aggregation is suggested by one author as a possible source of the melanosome. This fourth theory postulates that the melanosome originates when the protein products of several genetic loci aggregate in the cytoplasm of the melanocyte. It is this protein matrix on which the melanin is deposited. It was with these theories in mind that this project was undertaken.

scholarly journals Hepatic endosome fractions contain an ATP-driven proton pump

1985 ◽  
Vol 225 (1) ◽  
pp. 51-58 ◽  
Author(s):  
T Saermark ◽  
N Flint ◽  
W H Evans
Keyword(s):  
Endoplasmic Reticulum ◽  
Golgi Apparatus ◽  
Atpase Activity ◽  
Proton Pump ◽  
Subcellular Distribution ◽  
Plasma Membranes ◽  
Specific Activity ◽  
Ph Gradients ◽  
Subcellular Organelle ◽  
Liver Homogenates

Endosome fractions were isolated from rat liver homogenates on the basis of the subcellular distribution of circulating ligands, e.g. 125I-asialotransferrin internalized by hepatocytes by a receptor-mediated process. The distribution of endocytosed 125I-asialotransferrin 1-2 min and 15 min after uptake by liver and a monensin-activated Mg2+-dependent ATPase activity coincided on linear gradients of sucrose and Nycodenz. The monensin-activated Mg2+-ATPase was enriched relative to the liver homogenates up to 60-fold in specific activity in the endosome fractions. Contamination of the endosome fractions by lysosomes, endoplasmic reticulum, mitochondria, plasma membranes and Golgi-apparatus components was low. By use of 9-aminoacridine, a probe for pH gradients, the endosome vesicles were shown to acidify on addition of ATP. Acidification was reversed by addition of monensin. The results indicate that endosome fractions contain an ATP-driven proton pump. The ionophore-activated Mg2+-ATPase in combination with the presence of undegraded ligands in the endosome fractions emerge as linked markers for this new subcellular organelle.

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