Lamellae Of Rough Endoplasmic Reticulum Research Articles

Ultrastructural abnormalities with inclusions in Onuf's nucleus in motor neuron disease (amyotrophic lateral sclerosis).

This study describes an ultrastructural examination focused on motor neurons in Onuf's nucleus in the spinal cord of four control patients without neurological disease (45-70 years) and six motor neuron disease (MND) patients (38-79 years; duration 8 months-19 years) who showed no somato-vesical dysfunction. Prompted by recent studies suggesting some sphincteric motor neurons may succumb to MND, this study sought to determine whether the wider population of neurons in Onuf's nucleus display ultrastructural cytopathology which is normally undetectable in histological preparations. Spinal cords were removed 3-20 h after death, and 1 mm slices of cord rapidly fixed in modified Karnovsky medium were processed for both light- and electronmicroscopy. 'Control motor neurons' had intact neuronal and nuclear membranes. Nissl bodies chiefly comprised ordered structures of alternate lamellae of rough endoplasmic reticulum and arrays of polyribosomes. The Golgi complexes consisted of multilamellated curvilinear stacks of ER. No intraneuronal filamentous or Bunina body inclusions were observed, but occasional axonal spheroids were seen in the neuropil. In MND, histological evidence of sparing in Onuf's nucleus was associated with abnormal ultrastructure of the motor neurons. Some sphincteric neurons were atrophic, whereas in the others, Nissl bodies were reduced in number, showed loss of structural organization or comprised polyribosomal aggregates. Golgi complexes had disrupted lamellated organization or consisted solely of distended ER. Intraneuronal filamentous Lewy-body or skein-like inclusions and Bunina bodies were identified in Onuf's nucleus of three subjects (duration of MND 8 months-2 years). The results of the present study indicate that Onuf's nucleus is vulnerable in MND, and preservation of sphincter function with qualitative histological evidence of 'sparing' does not necessarily imply a corresponding lack of ultrastructural cytopathology in this nucleus.

The fine structure of aleurone cells in the soybean seed coat

The morphology and fine structure of aleurone cells of soybean [Glycine max (L.) Merr.] seed coats were analyzed with transmission electron microscopy for the period of rapid seed fill up to physiological maturity. Thin sections and freeze-fracture replicas were prepared for each stage. The aleurone is a tissue lining the embryo sac and consists of a single layer of cells attached to the aerenchyma of the seed coat proper. During seed fill, aleurone cells contained numerous Golgi-derived vesicles in the basal region of the cytoplasm that were either free or attached to the plasma membrane along the lateral and basal regions of the cell wall. Correspondingly, the Golgi apparatus were well developed with individual dictyosomes having 5 to 8, highly fenestrated stacked cisternae. The degree of fenestration along the periphery of each cisterna increased from the cis to trans region. Rough endoplasmic reticulum (RER) was also abundant, often consisting of up to 30, stacked swollen cisternae which occupied large regions of cytoplasm. Plasmodesmata which connected adjacent aleurone cells was not observed along the dorsal walls of aleurone cells that faced aerenchyma. At physiological maturity, dictyosome cisternae were less fenestrated and had fewer associated secretory vesicles. Stacked lamellae of RER were absent, being replaced by short tubular cisternae and small vesicles. At physiological maturity, the aleurone cells had thick walls, and contained numerous lipid bodies in apposition to the plasma membrane. The cytoplasm appeared densely stained in thin-sections and contained protein bodies and amyloplasts with large starch grains. We conclude that during the period of rapid seed fill aleurone cells produce, package, transport and secrete vesicular contents toward the embryo, that is followed at physiological maturity by the storage of lipid, protein and starch in the same cells. The embryo is the most likely destination for secretory products during the period of rapid seed fill. The fate of the stored food reserves in aleurone cells at physiological maturity may be analogous to that of aleurone tissue of grasses, being utilized during imbibition for processes important to germination.

Electron microscopic observations on the vomeronasal sensory epithelium of a crotaline snake, Trimeresurus flavoviridis.

The vomeronasal sensory epithelium of a crotaline snake, Trimeresurus flavoviridis, was shown to consist of a superficial supporting cell layer and an underlying sensory cell layer composed of columns of sensory cells. The supporting cell layer consists of both supporting cells and dendrites of the underlying sensory neurons. The apical regions of sensory cell dendrites contain numerous microtubules, many elongated mitochondria, centrioles, and electron-dense bodies. The dendrites terminate as dendritic knobs from which microvilli project into the vomeronasal lumen. Smooth vesicles are abundant in the dendritic terminals and their vicinity. Supporting cells also bear microvilli, and these cells contain large electron-opaque granules and dense vesicles near their free surfaces. Cytoplasmic extensions of the supporting cells form a meshwork which separates dendrxites from each other in the vicinity of the luminal surface. The meshwork becomes obliterated in the infranuclear region of each supporting cell. Bipolar-shaped sensory cells with lightly stained round nuclei contain the characteristic cell organelles of neurons and are thought to be sensory neurons. These cells are especially characterized by well-developed lamellae of rough endoplasmic reticulum and extensive arrays of smooth endoplasmic reticulum. The perikarya of cells located in the apical region of the cell columns tend to contain larger amounts of smooth endoplasmic reticulum and lipofuscin granules than the perikarya of cells located in lower regions. Undifferentiated cells are found in the basal region of the columns. Satellite cells form the framework of the columns and are also found among neuronal elements.

Immunoelectron microscopy of osteonectin and type I collagen in osteoblasts and bone matrix

The pathway of production, secretion, and extracellular deposition of type I collagen and osteonectin was studied by immunoelectron microscopy using respective polyclonal antibodies. Protein A gold and immunogold methods yielded to similar results in human callus tissue used as a model of bone formation. The intracellular distribution of osteonectin in active osteoblasts is found as a faint immunolabeling of vesicular Golgi fields and some lamellae of rough endoplasmic reticulum. A more intensive labeling occurs in opaque cytoplasmic vesicles pointing to the process of secretion as some of the vesicles are connected with the basal cell membrane. Our type I collagen antibody did not label the respective intracellular compartments. Extracellularly, the type I collagen antibody showed a continuous labeling from the immature subcellular osteoid to the mineralized bone. Osteonectin antibodies were bound first to the deeper layer of osteoid maturation with intensity increasing below the mineralization front. Osteonectin is thought to be associated with mineralization of bone matrix.

Annulate lamellae of the pancreatic exocrine cells in starved rats.

The ultrastructure of annulate lamellae in the pancreatic exocrine cells of rats starved for 3-42 days was studied. Annulate lamellae were rarely encountered in the pancreatic exocrine cells of control rats, but their incidence and size of stack was increased in those of starved rats depending on the duration of starvation, despite marked ultrastructural changes in these cells. Annulate lamellae were located in the para- or infranuclear cytoplasm of the cells and most of them were continuous with the relative normal rough endoplasmic reticulum. A close apposition in parallel was often found between the annulate lamellae and the outer nuclear envelope and occasionally pores in line with those of the nuclear membrane were observed in the lamellae of rough endoplasmic reticulum in 35- and 42-day-starved rats. An unequivocal continuity between the annulate lamellae and the nucleus and/or rough endoplasmic reticulum in pancreatic exocrine cells might be related to their origin and function.

Target dependence of Nissl body ultrastructure in cat thoracic motoneurones

The effects on Nissl body (NB) ultrastructure of muscle reinnervation or neuroma formation were determined in cytochemically identified cat thoracic motoneurones subjected to axotomy by either nerve crush or nerve section with proximal ligation. Normal NB ultrastructure comprised highly ordered lamellae of rough endoplasmic reticulum (RER) with associated linear arrays of unbound polyribosomes. This ultrastructural orderliness was lost following axotomy, with or without light microscopic chromatolysis. While NBs were seen in the light microscope at late stages following both nerve crush or ligation, normal NB ultrastructure was only observed following nerve crush. An inductive effect of the periphery on NB ultrastructure is proposed and the implications of NB ultrastructure discussed in relation to protein synthesis.

The Effect of Abscisic Acid on the Ultrastructure of Barley Aleurone Cells

The effects of abscisic acid (ABA) on the ultrastructure of barley (Hordeum vulgare L.) aleurone cells were examined in the absence and presence of gibberellic acid (GA), using a new low-viscosity resin. Control cells are characterized by an extensive network of tubular rough endoplasmic reticulum (RER) elements. GA-treated cells contain stacked RER lamellae adjacent to the nucleus. ABA causes two distinctive changes in aleurone cells: the spherosomes align preferentially along more than 70% of the plasma membrane, and the ER takes on the appearance of isolated strands, which may represent an intermediate form between the tubular network of the control and the stacked cisternae of the GA-treated cells. These findings suggest that ABA has positive regulatory effects, rather than a strictly inhibitory action, in relation to GA.

The ultrastructure of developing wings in the giant silkmoth, Hyalophora cecropia. I. Generalized epidermal cells.

AbstractThe ultrastructure of wing epidermis of the giant silkmoth, Hyalophora cecropia, was studied during pupal diapause and the first half of development to the adult. In diapause, the generalized epidermal cells are characterized by many free ribosomes, some vesicles and small lamellae of rough endoplasmic reticulum, some scattered short mitochondria and a few small Golgi complexes. During the early states of post‐diapause development, before and after the time of apolysis (separation of the epidermis from the overlying cuticle), there is a marked increase in structures often associated with synthetic functions, such as polyribosomes, lamellate rough endoplasmic reticulum and Golgi complexes. On day five of post‐apolysis development, just after the appearance of scale‐forming and socket‐forming cells, the generalized epidermal cells lay down the cuticulin layer of the adult cuticle. At this stage and later, the polyribosomes and lamellate rough endoplasmic reticulum decrease in abundance. Cell nuclei show three phases of temporary transition from predominantly lobed to predominantly round profile, which correspond to periods of reported DNA synthesis. Throughout this developmental process, therefore, there is good correlation of fine structure with changes in macromolecular synthesis recorded elsewhere.

Fine structure of the Mongolian gerbil adrenal cortex.

AbstractThe relative weight of the Mongolian gerbil adrenal is one of the largest of any animal species. The adrenal cortex of the gerbil can be divided into three major zones and one zone located between th zona fasciculata and zona reticularis. Mitochondrial cristae of zona glomerulosa cells are plate‐like, those of the zona fasciculata are tubular whereas cristae are extensively developed and plate‐like in the zona reticularis. Lipid droplets are numerous in fasciculata cells and sparse in glomerulosa and reticularis cells. Fasciculata and glomerulosa cells contain tubules of smooth endoplasmic reticulum whereas rough reticulum predominates in reticularis and border cells. Abundant lysosomes are found in glomerulosa cells; lysosomes are aggregated beneath the cell membrane of reticularis cells. Whorls of concentric lamellae of rough endoplasmic reticulum are localized exclusively to cells in the border zone. Cells in the border zone resemble those of the reticularis because of a virtual absence of smooth endoplasmic reticulum although mitochondrial cristae are tubular and therefore similar to those of the zona fasciculata. It is suggested that cells in the border zone represent a reserve of cells which may transform into fasciculata cells upon stimulation.