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The endoplasmic reticulum (ER) in animal cells is an extensive, morphologically continuous network of membrane tubules and flattened cisternae. The ER is a multifunctional organelle; the synthesis of membrane lipids, membrane and secretory proteins, and the regulation of intracellular calcium are prominent among its array of functions. Many of these(More)
The acinous salivary glands of the cockroach (Periplaneta americana) consist of four morphologically different cell types with different functions: the peripheral cells are thought to produce the fluid component of the primary saliva, the central cells secrete the proteinaceous components, the inner acinar duct cells stabilize the acini and secrete a(More)
The composition of dark-adapted and illuminated retinal rod outer and inner segments and mitochondria was determined with electron probe X-ray micro-analysis of cryosections. The concentration of Ca in the outer segment was 0.4 mmol/kg dry wt. (0.1 Ca/rhodopsin) and did not measurably change upon illumination with saturating light for 5 min. The(More)
The photoreceptor cells in the honeybee drone contain an elaborate Ca2+-sequestering endoplasmic reticulum (ER). We measured Ca-oxalate formation within the ER of permeabilized retinal slices with a microphotometer and studied the kinetics of Ca2+-uptake into the ER and the properties of Ins(1,4,5)P3-induced Ca2+-release. The ATP-dependent Ca2+-uptake(More)
The photoreceptive microvilli in the visual cells of the leech protrude into a large ‘intracellular vacuole’ which is but an extracellular compartment (ionic composition unknown), because it communicates with the extracellular space by narrow (≅ 20 nm) clefts (septate junctions) of unknown permeability properties. Application of Thiéry's cytochemical silver(More)
Superfused slices of drone retina were used for a quantitative analysis of light-induced changes in extracellular Ca2+ concentration ([Ca2+]o) and extracellular space (ECS) volume. 20-ms light flashes elicited biphasic changes in [Ca2+]o. For a saturating flash a brief, initial decrease was followed by a transient increase of 120±34 μM. Long, dim steps of(More)
In the anterior head region ofMacrobiotus hufelandi four sensory regions were identified, and a detailed description of their fine structure follows. According to their position in the head region the sensory regions were called; I. anterio-lateral sensory field (ALSF), II. circum-oral sensory field (COSF), III. sub-oral sensory region (SOSR), and IV.(More)
  • B Walz
  • 1982
Microphotometric measurements are used to investigate the functional properties of Ca2+-sequestering smooth endoplasmic reticulum (SER) in leech photoreceptors. 10-30 intact cells are mounted in a perfusion chamber, placed between crossed polarizers in a microphotometer, and permeabilized by saponin treatment. Subsequent perfusion with solutions containing(More)
The endoplasmic reticulum (ER) in the photoreceptors of the honeybee drone, Apis mellifera, is highly differentiated and morphologically more complex than suggested by previous studies. In addition to the prominent voluminous submicrovillar cisternae we describe a submitochondrial ER. It separates the mitochondria-containing periphery from the core of the(More)
Light-dependent changes in the positioning of organelles in photoreceptor cells of arthropods are a well-known phenomenon. In this study, we examine the role of the cytoskeleton in these light-dependent antagonistic movements. In dark-adapted photoreceptor cells of the locust Schistocerca gregaria, prominent sacs of smooth endoplasmic reticulum (ER) oppose(More)