scholarly journals The Ultrastructure of the Cement Gland in Xenopus laevis

1966 ◽  
Vol 1 (2) ◽  
pp. 193-200 ◽  
Author(s):  
MARGARET M. PERRY ◽  
C. H. WADDINGTON
Keyword(s):  
Endoplasmic Reticulum ◽  
Xenopus Laevis ◽  
Secretory Granules ◽  
Progressive Increase ◽  
Cement Gland ◽  
Membrane Systems ◽  
Large Numbers ◽  
Cytoplasmic Filaments ◽  
Golgi Zone ◽  
Neurula Stage

Alterations which occur during differentiation in the fine structure of the cement gland of the embryo of Xenopus laevis have been investigated. The organ anlage at the late neurula stage is composed of cuboidal cells of comparatively simple cytoplasmic structure. Coincident with the subsequent cellular elongation there is a formation of extensive arrays of functionally interrelated membrane systems, leading to the production of a mucin-like secretory substance. Although there is no direct structural continuity between the membranes of the endoplasmic reticulum and the Golgi apparatus, small vesicles which seem to originate from areas of agranular reticulum appear to transport material synthesized in the endoplasmic reticulum to the Golgi zone. Further elaboration of the product at the site of the Golgi material is suggested by the progressive increase in the quantity of the contents as the cisternae enlarge to form secretory granules. Other notable features of the differentiating cells are microtubules and cytoplasmic filaments, many of which are oriented in the direction of cellular elongation. In suitably preserved specimens, large numbers of glycogen granules are present. The degenerating gland is characterized by the appearance of large autolytic vacuoles within the cytoplasm. Traces of the membrane systems are present and, in many cells, there remain large numbers of secretory granules.

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).

EFFECTS OF INTRADUCTAL PROLACTIN ON SOME ASPECTS OF THE ULTRA-STRUCTURE AND BIOCHEMISTRY OF MAMMARY TISSUE IN THE PSEUDOPREGNANT RABBIT

1971 ◽  
Vol 49 (3) ◽  
pp. 459-469 ◽  
Author(s):  
T. J. FIDDLER ◽  
MARGARET BIRKINSHAW ◽  
I. R. FALCONER
Keyword(s):  
Endoplasmic Reticulum ◽  
Epithelial Cells ◽  
Rough Endoplasmic Reticulum ◽  
Mammary Epithelial Cells ◽  
Smooth Endoplasmic Reticulum ◽  
Progressive Increase ◽  
Mammary Epithelial ◽  
Mammary Tissue ◽  
Hormone Administration ◽  
Large Numbers

SUMMARY A study of the ultrastructure of the secretory epithelial cells of the mammary gland was carried out in virgin oestrous rabbits, pseudopregnant rabbits and pseudopregnant rabbits injected with prolactin to induce lactogenesis. Ultrastructural modifications of the mammary epithelial cells, from inactivity to active secretion after an intraductal injection of prolactin, are described. The changes produced after prolactin injection were characterized by a progressive increase in endoplasmic reticulum and in ribosomes in the cytoplasm. This was evident after 12–24 h. By the 2nd or 3rd day after hormone administration the cells had differentiated into active secretory epithelium. These cells were characterized by large numbers of ribosomes in the cytoplasm; an extensive development of rough endoplasmic reticulum; development of cisternae from the enlarging rough endoplasmic reticulum; hypertrophy of the Golgi apparatus and smooth endoplasmic reticulum; and the presence of protein granules in the vacuoles which were particularly abundant in the cytoplasm near the duct lumen. The presence of lipid droplets in the cells was less indicative of an active secretory state since they were also observed in mammary tissue from pseudopregnant rabbits. Biochemical investigation of the response of pseudopregnant mammary tissue to intraductal prolactin showed no significant rapid effects on either casein-like protein or lactose biosynthesis, but increases in both substances were observed on the 3rd day after hormone administration.

The behaviour of the egg pigment in wild-type and ‘rusty’ tadpoles of Xenopus laevis

Development ◽  
1971 ◽  
Vol 26 (3) ◽  
pp. 571-585
Author(s):  
V. Uehlinger ◽  
M. L. Beauchemin ◽  
A. Droin
Keyword(s):  
Xenopus Laevis ◽  
Neural Tube ◽  
Histological Analysis ◽  
Exceptional Case ◽  
Cement Gland ◽  
Wild Type ◽  
Specific Process ◽  
Pigment Migration ◽  
Characteristic Colour ◽  
Neurula Stage

The behaviour of the egg pigment was studied by histological analysis of wild-type and ‘rusty’ embryos and tadpoles of Xenopus laevis as well as by experimental procedures. The histological analysis of the wild-type animals showed that the various tissues, notably the skin, neural tube, alimentary system and cement gland go through progressive stages of egg pigment migration and concentration at the apical ends of the cells. In the ‘rusty’ mutants the migration and concentration of pigment occur to a slight extent only, the majority of the pigment granules remaining dispersed. The experiments (tail cultures, squashes of cement gland mucus and of meconium) showed that in wild-type animals the pigment, after migration and concentration, is eliminated from the cells by expulsion. In ‘rusty’ animals, this expulsion does not take place. Parabiotic tadpoles of a ‘rusty’ wild-type combination possess a coloration corresponding to their genotype. Ectodermal grafts performed at the neurula stage between ‘rusty’ and wild-type embryos develop according to their origin. The amount of egg pigment found in wild-type and ‘rusty’ tadpoles, and the exceptional case of the cement gland are discussed. It is concluded that the behaviour of the egg pigment is an active cell-specific process, and that the pigment is eliminated by expulsion. The non-elimination of the egg pigment in the ‘rusty’ mutant, accounting for its characteristic colour, appears to be due to a failure of the expulsion mechanism.

Ultrastructural comparison of prolactin adenomas of pituitary in men and women

1988 ◽  
Vol 46 ◽  
pp. 346-347
Author(s):  
R.C. Caughey ◽  
U.P. Kalyan-Raman
Keyword(s):  
Endoplasmic Reticulum ◽  
Electron Microscope ◽  
Phosphate Buffer ◽  
Pituitary Adenomas ◽  
Osmium Tetroxide ◽  
Secretory Granules ◽  
Uranyl Acetate ◽  
En Bloc ◽  
Men And Women ◽  
Transmission Electron

Prolactin producing pituitary adenomas are ultrastructurally characterized by secretory granules varying in size (150-300nm), abundance of endoplasmic reticulum, and misplaced exocytosis. They are also subclassified as sparsely or densely granulated according to the amount of granules present. The hormone levels in men and women vary, being higher in men; so also the symptoms vary between both sexes. In order to understand this variation, we studied 21 prolactin producing pituitary adenomas by transmission electron microscope. This was out of a total of 80 pituitary adenomas. There were 6 men and 15 women in this group of 21 prolactinomas.All of the pituitary adenomas were fixed in 2.5% glutaraldehyde, rinsed in Millonig's phosphate buffer, and post fixed with 1% osmium tetroxide. They were then en bloc stained with 0.5% uranyl acetate, rinsed with Walpole's non-phosphate buffer, dehydrated with graded series of ethanols and embedded with Epon 812 epoxy resin.

Localization of Intracisternal a Particle Antigens in Neoplastic Cells and Preimplantation Mouse Embryos

1980 ◽  
Vol 38 ◽  
pp. 696-697
Author(s):  
Thomas T.F. Huang ◽  
Patricia G. Calarco
Keyword(s):  
Endoplasmic Reticulum ◽  
Normal Development ◽  
Mouse Embryos ◽  
Neoplastic Cells ◽  
Large Numbers ◽  
Preimplantation Mouse Embryos ◽  
Preimplantation Mouse ◽  
Intracisternal A Particle ◽  
Normal Feature

The stage specific appearance of a retravirus, termed the Intracisternal A particle (IAP) is a normal feature of early preimplantation development. To date, all feral and laboratory strains of Mus musculus and even Asian species such as Mus cervicolor and Mus pahari express the particles during the 2-8 cell stages. IAP form by budding into the endoplasmic reticulum and appear singly or as groups of donut-shaped particles within the cisternae (fig. 1). IAP are also produced in large numbers in several neoplastic cells such as certain plasmacytomas and rhabdomyosarcomas. The role of IAP, either in normal development or in neoplastic behavior, is unknown.

scholarly journals DEVELOPMENT OF ENDOGENOUS PEROXIDASE IN FETAL RAT SUBMANDIBULAR GLAND

1973 ◽  
Vol 21 (1) ◽  
pp. 42-50 ◽  
Author(s):  
SHOHEI YAMASHINA ◽  
TIBOR BARKA
Keyword(s):  
Endoplasmic Reticulum ◽  
Nuclear Envelope ◽  
Submandibular Gland ◽  
Rough Endoplasmic Reticulum ◽  
Peroxidase Activity ◽  
Secretory Granules ◽  
Prenatal Development ◽  
Reaction Products ◽  
Cell Type ◽  
Endogenous Peroxidase

The prenatal development of endogenous peroxidase activity in the submandibular gland of rat was investigated by means of the diaminobenzidine-H2O2 histochemical method. The submandibular gland of a 16-day-old fetus was composed of cords of uniform, undifferentiated cells which contained no secretory granules and revealed no peroxidase activity. Peroxidase activity first appeared at the 17th day of gestation in the cisternae of the rough endoplasmic reticulum and nuclear envelope in a few cells. At the 18th day of gestation cells which exhibited reaction products in the rough endoplasmic reticulum and nuclear envelope also contained secretory granules with a strong peroxidase activity. During the last days of gestation the number of peroxidase positive cells, which contained numerous secretory granules, increased. The peroxidase-containing cells are the immediate precursors of the proacinar cells of early postnatal stages. During the same time period, when the peroxidase-containing cells differentiated, a second cell type also differentiated in the cellular cords. The development of this cell type was marked by the appearance of secretory granules stainable with toluidine blue. Through the prenatal development, this cell type revealed no peroxidase activity and was identified with the terminal tubule cell of the newborn. The morphologic and cytochemical findings indicate that terminal tubule cells and proacinar cells are committed cells; the former differentiate toward 2nd order intercalated duct cells and the latter transform to mature acinar cells.

scholarly journals SYNTHESIS, MIGRATION, AND RELEASE OF PRECURSOR COLLAGEN BY ODONTOBLASTS AS VISUALIZED BY RADIOAUTOGRAPHY AFTER [3H]PROLINE ADMINISTRATION

1974 ◽  
Vol 60 (1) ◽  
pp. 92-127 ◽  
Author(s):  
Melvyn Weinstock ◽  
C. P. Leblond
Keyword(s):  
Electron Microscopy ◽  
Endoplasmic Reticulum ◽  
Golgi Apparatus ◽  
Phosphotungstic Acid ◽  
Secretory Granules ◽  
Low Ph ◽  
Collagen Fibrils ◽  
Dentin Collagen ◽  
Odontoblast Process ◽  
High Radioactivity

The elaboration of dentin collagen precursors by the odontoblasts in the incisor teeth of 30–40-g rats was investigated by electron microscopy, histochemistry, and radioautography after intravenous injection of tritium-labeled proline. At 2 min after injection, when the labeling of blood proline was high, radioactivity was restricted to the rough endoplasmic reticulum, indicating that it is the site of synthesis of the polypeptide precursors of collagen, the pro-alpha chains. At 10 min, when the labeling of blood proline had already declined, radioactivity was observed in spherical portions of Golgi saccules containing entangled threads, and, at 20 min, radioactivity appeared in cylindrical portions containing aggregates of parallel threads. The parallel threads measured 280–350 nm in length and stained with the low pH-phosphotungstic acid technique for carbohydrate and with the silver methenamine technique for aldehydes (as did extracellular collagen fibrils). The passage of label from spherical to cylindrical Golgi portions is associated with the reorganization of entangled into parallel threads, which is interpreted as the packing of procollagen molecules. Between 20 and 30 min, prosecretory and secretory granules respectively became labeled. These results indicate that the cylindrical portions of Golgi saccules transform into prosecretory and subsequently into secretory granules. Within these granules, the parallel threads, believed to be procollagen molecules, are transported to the odontoblast process. At 90 min and 4 h after injection, label was present in predentin, indicating that the labeled content of secretory granules had been released into predentin. This occurred by exocytosis as evidenced by the presence of secretory granules in fusion with the plasmalemma of the odontoblast process. It is proposed that pro-alpha chains give rise to procollagen molecules which assemble into parallel aggregates in the Golgi apparatus. Procollagen molecules are then transported within secretory granules to the odontoblast process and released by exocytosis. In predentin procollagen molecules would give rise to tropocollagen molecules, which would then polymerize into collagen fibrils.

scholarly journals The Lamellar Systems of Cytoplasmic Membranes in Dividing Spermatogenic Cells of Drosophila virilis

1960 ◽  
Vol 7 (3) ◽  
pp. 433-441 ◽  
Author(s):  
Susumu Ito
Keyword(s):  
Endoplasmic Reticulum ◽  
Golgi Complex ◽  
Light And Electron Microscopy ◽  
Primary Spermatocyte ◽  
Drosophila Virilis ◽  
Spermatogenic Cells ◽  
Membrane Systems ◽  
Cytoplasmic Membranes ◽  
Pas Reaction ◽  
Staining Methods

Spermatogenic cells of Drosophila virilis were studied by light and electron microscopy. The persistence of a "nuclear wall" during the meiotic divisions has been reported by a number of early cytologists, but this interpretation has been a subject of debate. Electron micrographs of dividing spermatocytes reveal the presence of multiple layers of paired membranes surrounding the nuclear region. These lamellar membrane systems are not typical of the nuclear envelope, but were interpreted as such by light microscopists. The membranes constituting a pair are separated by an interspace of ∼ 100 A and successive pairs are 200 to 400 A apart. These spacings are similar but not identical to those found in the lamellar systems of the Golgi complex. The cisternae of the endoplasmic reticulum in this material are devoid of attached ribonucleoprotein particles, are more precisely ordered than in vertebrate cells, and show a uniform, narrow intracisternal space of ∼ 100 A. The conspicuous asters appear to be made up of similar paired membranes radiating from the centriolar region. The primary spermatocyte has numerous dictyosomes and a well developed endoplasmic reticulum in cisternal form, but no typical Golgi complex or endoplasmic reticulum is found during the meiotic division stages of metaphase to telophase. Evidence is presented that these cytoplasmic organelles contribute to the formation of the extensive lamellar systems that appear during meiosis. The results of the Golgi silver staining methods and staining tests for phospholipids, basophilia, and the PAS reaction, indicate that the lamellar arrays of membranes present during meiosis are indistinguishable from the Golgi complex in their tinctorial properties.

scholarly journals INDUCTION OF ENDOMETRIAL PEROXIDASE SYNTHESIS AND SECRETION BY ESTROGEN AND ESTROGEN ANTAGONIST

1974 ◽  
Vol 62 (2) ◽  
pp. 449-459 ◽  
Author(s):  
Andrew Churg ◽  
Winston A. Anderson
Keyword(s):  
Endoplasmic Reticulum ◽  
Golgi Apparatus ◽  
Peroxidase Activity ◽  
Secretory Granules ◽  
Combined Treatment ◽  
Initial Injection ◽  
Immature Rats ◽  
Glandular Cells ◽  
Endogenous Peroxidase ◽  
Estrogen Antagonist

Synthesis of peroxidase was induced in the uterine epithelium of immature rats by multiple doses over a 24–96-h period of either 17 ß-estradiol, the estrogen-antagonist Parke-Davis CI-628, or a combination of estradiol plus antagonist. Endogenous peroxidase activity first appeared in the cisternae of the rough endoplasmic reticulum of surface epithelial and glandular cells within 24–48 after the initial injection. Uterine peroxidase activity was also visible in the cisternae of the Golgi apparatus, in Golgi-derived secretory granules, and within the uterine and glandular lumen. Some cells of the epithelium produced little or no peroxidase, even after 96 h. Whereas the antagonist appeared to induce synthesis and secretion of peroxidase, neither the antagonist alone nor the combined treatment (estradiol plus antagonist) reproduced the estradiol-mediated growth in organ size and increased lumen diameter.

Structure of the chloroplast and its DNA in chloromonadophycean algae

1981 ◽  
Vol 49 (1) ◽  
pp. 401-409
Author(s):  
A.W. Coleman ◽  
P. Heywood
Keyword(s):  
Endoplasmic Reticulum ◽  
Cell Membrane ◽  
Nuclear Envelope ◽  
Chloroplast Dna ◽  
Single Layer ◽  
Longitudinal Axis ◽  
Chloroplast Envelope ◽  
Large Numbers ◽  
Gonyostomum Semen ◽  
Chloroplast Stroma

The arrangement and ultrastructure of chloroplasts is described for the Chloromonadophycean algae gonyostomum semen Diesing and Vacuolaria virescens Cienkowsky. The chloroplasts are present in large numbers and are discoid structures approximately 3–4 micrometer in length by 2–3 micrometer in width. In Gonyostomum semen the chloroplasts form a single layer immediately interior to the cell membrane; frequently their longitudinal axis parallels the longitudinal axis of the cell. The chloroplasts in Vacuolaria virescens are more than I layer deep and do not appear to be preferentially oriented. In both organisms, chloroplast bands usually consist of 3 apposed thylakoids, although fusion and interconnections between adjacent bands frequently occur. External to the girdle band (the outermost thylakoids) is the chloroplast envelope. This is bounded by endoplasmic reticulum but there is no immediately apparent continuity between this endoplasmic reticulum and the nuclear envelope. Electron-dense spheres in the chloroplast stroma are thought to be lipid food reserve. Ring-shaped electron-translucent regions in the chloroplast contain chloroplast DNA. The DNA is distributed along this ring in an uneven fashion and, when stained, resembles a string of beads. Each plastid has I ring, and the ring is unbroken in the intact plastid.

Sign in / Sign up

Export Citation Format

Share Document