scholarly journals Lectin-labeled membrane is transferred to the Golgi complex in mouse pituitary cells in vivo.

1987 ◽  
Vol 35 (4) ◽  
pp. 489-498 ◽  
Author(s):  
B J Balin ◽  
R D Broadwell
Keyword(s):  
Golgi Complex ◽  
Secretory Granules ◽  
Surface Membrane ◽  
Dense Core ◽  
Secretory Cells ◽  
Pituitary Cells ◽  
Posterior Pituitary ◽  
Peroxidase Reaction ◽  
Mouse Pituitary

Labeling of the Golgi complex with the lectin conjugate wheat germ agglutinin-horseradish peroxidase (WGA-HRP), which binds to cell surface membrane and enters cells by adsorptive endocytosis, was analyzed in secretory cells of the anterior, intermediate, and posterior lobes of mouse pituitary gland in vivo. WGA-HRP was administered intravenously or by ventriculo-cisternal perfusion to control and salt-stressed mice; post-injection survival times were 30 min-24 hr. Peroxidase reaction product was identified within the extracellular clefts of anterior and posterior pituitary lobes through 24 hr but was absent in intermediate lobe. Endocytic vesicles, spherical endosomes, tubules, dense and multivesicular bodies, the trans-most saccule of the Golgi complex, and dense-core secretory granules attached or unattached to the trans Golgi saccule were peroxidase-positive in the different types of anterior pituitary cells and in perikarya of supraoptico-neurohypophyseal neurons; endoplasmic reticulum and the cis and intermediate Golgi saccules in the same cell types were consistently devoid of peroxidase reaction product. Dense-core secretory granules derived from cis and intermediate Golgi saccules in salt-stressed supraoptic perikarya likewise failed to exhibit peroxidase reaction product. The results suggest that in secretory cells of anterior and posterior pituitary lobes, WGA-HRP, initially internalized with cell surface membrane, is eventually conveyed to the trans-most Golgi saccule, in which the lectin conjugate and associated membrane are packaged in dense-core secretory granules for export and potential exocytosis of the tracer. Endoplasmic reticulum and the cis and intermediate Golgi saccules appear not to be involved in the endocytic/exocytic pathways of pituitary cells exposed to WGA-HRP.

Ultrastructural Aspects of Golgi Complex Function in Parathyroid Cells of Winter Frogs

1973 ◽  
Vol 31 ◽  
pp. 680-681
Author(s):  
William J. Dougherty
Keyword(s):  
Golgi Complex ◽  
Secretory Granules ◽  
Complex Function ◽  
Secretory Activity ◽  
Secretory Proteins ◽  
Perivascular Spaces ◽  
Pituitary Cells ◽  
Electron Microscopic ◽  
Ca Ions ◽  
Regulation Of Secretion

The regulation of secretion in exocrine and endocrine cells has long been of interest. Electron microscopic and other studies have demonstrated that secretory proteins synthesized on ribosomes are transported by the rough ER to the Golgi complex where they are concentrated into secretory granules. During active secretion, secretory granules fuse with the cell membrane, liberating and discharging their contents into the perivascular spaces. When secretory activity is suppressed in anterior pituitary cells, undischarged secretory granules may be degraded by lysosomes. In the parathyroid gland, evidence indicates that the level of blood Ca ions regulates both the production and release of parathormone. Thus, when serum Ca is low, synthesis and release of parathormone are both stimulated; when serum Ca is elevated, these processes are inhibited.

scholarly journals Synthesis of membrane glycoproteins in rat small-intestinal villus cells. Redistribution of l-[1,5,6-3H]-fucose-labelled membrane glycoproteins among Golgi, lateral basal and microvillus membranes in vivo

1979 ◽  
Vol 182 (1) ◽  
pp. 203-212 ◽  
Author(s):  
Andrea Quaroni ◽  
Katharina Kirsch ◽  
Milton M. Weiser
Keyword(s):  
Golgi Complex ◽  
Membrane Fraction ◽  
Surface Membrane ◽  
Sodium Dodecyl ◽  
Membrane Glycoproteins ◽  
Intestinal Villus ◽  
Microvillus Membrane ◽  
Small Intestinal ◽  
Small Intestinal Villus

The biogenesis of plasmalemma glycoproteins of rat small-intestinal villus cells was studied by following the incorporation of l-[1,5,6-3H]fucose, given intraperitoneally with and without chase, into Golgi, lateral basal and microvillus membranes. Each membrane fraction showed distinct kinetics of incorporation of labelled fucose and was differently affected by the chase, which produced a much greater decrease in incorporation of label into Golgi and microvillus than into lateral basal membranes. The kinetic data suggest a redistribution of newly synthesized glycoproteins from the site of fucosylation, the Golgi complex, directly into both lateral basal and microvillus membranes. The observed biphasic pattern of label incorporation into the microvillus membrane fraction may be evidence for a second indirect route of incorporation. The selective effect of the chase suggests the presence of two different pools of radioactive fucose in the Golgi complex that differ in (1) their accessibility to dilution with non-radioactive fucose, and (2) their utilization for the biosynthesis of membrane glycoproteins subsequently destined for either the microvillus or the lateral basal parts of the plasmalemma. The radioactively labelled glycoproteins of the different membrane fractions were separated by sodium dodecyl sulphate/polyacrylamide-slab-gel electrophoresis and identified by fluorography. The patterns of labelled glycoproteins in Golgi and lateral basal membranes were identical at all times. At least 14 bands could be identified shortly after radioactive-fucose injection. Most seemed to disappear at later times, although one of them, which was never observed in microvillus membranes, increased in relative intensity. All but two of the labelled glycoproteins present in the microvillus membrane corresponded to those observed in Golgi and lateral basal membranes shortly after fucose injection. The patterns of labelled glycoproteins in all membrane fractions were little affected by the chase. These data support a flow concept for the insertion of most surface-membrane glycoproteins of the intestinal villus cells.

Studies on the Development of Ameloblasts

1972 ◽  
Vol 11 (2) ◽  
pp. 415-447 ◽  
Author(s):  
E. KATCHBURIAN ◽  
S. J. HOLT
Keyword(s):  
Endoplasmic Reticulum ◽  
Golgi Complex ◽  
Structural Changes ◽  
Surface Membrane ◽  
Secretory Cells ◽  
Enamel Matrix ◽  
Coated Pits ◽  
Cytoplasmic Extension ◽  
Distal Surface ◽  
Oriented Parallel

The cellular and fine-structural changes which take place during differentiation of ameloblasts into highly secretory cells involve growth and elongation of the cytoplasm, a change in polarity, and sequential development of organelles. The undifferentiated cells of the ameloblastic layer seem to be mainly concerned with the production of material for internal use, as they are rich in free ribosomes and have only few profiles of rough-surfaced endoplasmic reticulum. First signs of differentiation are detected when the cells begin to elongate and large numbers of microtubules oriented parallel to the cell long axis appear in the distal cytoplasm. This suggests that the microtubules provide directional guidance for the elongation of the cells. The next stage of differentiation is characterized by proliferation of the rough-surfaced endoplasmic reticulum in the distal cytoplasm and the migration of the small Golgi complex, initially at the base of the cell, to the distal cytoplasm. Intracisternal accumulation of enamel matrix-like material in the rough-surfaced endoplasmic reticulum at this stage suggests that the Golgi complex is unable to process for secretion the materials synthesized in the rough-surfaced endoplasmic reticulum. However, the presence of enamel matrix-like material in the intercellular spaces may indicate an attempt to secrete matrix by a mechanism which by-passes the Golgi complex. With further differentiation the Golgi complex reaches the distal cytoplasm where it develops and becomes very extensive. The appearance of enamel matrix-like material in the cisternae of the mature Golgi complex and in large secretion granules in secretory ameloblasts suggests that secretory material is processed in a manner similar to that of other exocrine cells. As soon as enamel matrix begins to be deposited at the distal surface, ameloblasts withdraw, leaving the cytoplasmic extension (Tomes process) in the early calcifying enamel. The presence of microtubules and filaments in both the early and late developing Tomes process suggests that they play a role in the directional and localized growth of this constricted cell extension. Based on previous evidence that the Tomes process has an extensive lysosomal system and on the observation that its surface membrane possesses numerous invaginations and coated pits, it is concluded that the present findings support the concept that the Tomes process - via its lysosomal vacuolar apparatus - plays a role in the changes which occur in the enamel matrix in early amelogenesis.

scholarly journals Immunohistochemical localization and expression of the hyaluronan receptor CD44 in the epithelium of the pig oviduct during oestrus

Reproduction ◽  
2003 ◽  
pp. 119-132 ◽  
Author(s):  
P Tienthai ◽  
M Yokoo ◽  
N Kimura ◽  
P Heldin ◽  
E Sato ◽  
...  
Keyword(s):  
Cell Surface ◽  
Surface Membrane ◽  
Cumulus Cell ◽  
Secretory Cells ◽  
Specific Cell ◽  
Protein Determination ◽  
Sperm Reservoir ◽  
Hyaluronan Receptor

Hyaluronan is related to essential reproductive processes in pigs. Hyaluronan produced by cumulus cells builds, via specific cell surface receptors, an extracellular matrix responsible for cumulus cell cloud expansion during final oocyte maturation, a preparatory event for ovulation and fertilization. In addition, hyaluronan that has been localized in the pig oviduct both in the intraluminal fluid and on the surface of the lining epithelium of the preovulatory sperm reservoir, has proven beneficial during in vitro fertilization and embryo culture, thus indicating that it has a role in vivo. This study monitored the immunolocalization, protein determination and gene expression of the major cell surface hyaluronan receptor CD44 in the epithelial lining of the pig oviduct during selected stages of standing oestrus, in relation to spontaneous ovulation. The CD44 immunostaining in the lining epithelium was localized to the surface membrane and the supranuclear domain of mainly the secretory cells, particularly in the sperm reservoir of both treatment (inseminated) and control (non-inseminated) specimens. Up to four hyaluronan-binding protein (HABP) bands (60, 90, 100 and 200 kDa) were detected in the tubal epithelium, and the 200 kDa band was determined as CD44 by immunoblotting. The expression of CD44 mRNA was higher before than after ovulation (P < 0.05), most conspicuously in the uterotubal junction (UTJ). In addition, CD44 expression in the preovulatory UTJ and the ampullary-isthmic junction (AIJ) of control animals was higher than in those that were inseminated (P < 0.05 and P < 0.01 for UTJ and AIJ, respectively). The results demonstrate for the first time that the specific hyaluronan receptor CD44 is expressed by the oviduct epithelial cells during spontaneous oestrus, and is particularly abundant in the sperm reservoir before ovulation. Presence of spermatozoa in this segment seemed to downregulate the receptor. The variation in the expression of CD44 in relation to spontaneous ovulation and the presence of spermatozoa indicate that the hyaluronan CD44-signalling pathway may play a role in oviduct function during sperm storage and fertilization in pigs.

scholarly journals High resolution analysis of the secretory pathway in mammotrophs of the rat anterior pituitary.

1981 ◽  
Vol 91 (1) ◽  
pp. 240-246 ◽  
Author(s):  
M M Salpeter ◽  
M G Farquhar
Keyword(s):  
High Resolution ◽  
Golgi Complex ◽  
Secretory Granules ◽  
Female Rats ◽  
Secretory Process ◽  
Pituitary Cells ◽  
Secretory Product ◽  
Electron Microscope Autoradiography ◽  
New Findings ◽  
Density Analysis

The secretory process in pituitary mammotrophs was analyzed by quantitative electron microscope autoradiography. Dispersed pituitary cells from estrogen-treated female rats were subjected to pulse-labeling with [3H]leucine (5 min) followed by a chase incubation of up to 4 h. Autoradiograms were prepared using fine-grained emulsion (Kodak 129-01), and analyzed using a three-step "mask analysis' procedure: (a) the distribution of autoradiographic grains is determined as in a simple grain density analysis; (b) masks (transparent overlays) are used to generate expected grains from assumed sources; and (c) a computer program compares these two distributions and varies the expected distribution to match the observed distribution, thereby identifying the radioactive sources in the tissue. The overall route of intracellular transport of prolactin from rough endoplasmic reticulum (ER) leads to Golgi complex leads to immature secretory granules leads to mature secretory granules was as established in previous studies. However, by use of the high resolution emulsion and method of analysis, the precision with which label could be localized within individual source compartments was much greater and the time resolution was much sharper than achieved previously using Ilford L4 emulsion and simple grain density analysis. The main new findings were as follows: (a) the ER was essentially drained of radioactivity by 30 min, the Golgi complex by 1 h, and the immature secretory granules by 2h postpulse. This indicates that the secretory product (prolactin) is rapidly and efficiently transported out of these compartments. (b) approximately 30% of the total radioactivity remains located in the ground cytoplasm over the entire postpulse period examined (up to 4 h), and by 30 min postpulse the grain density in the ground cytoplasm exceeded that of the ER. This indicates the ability to resolve ER-associated label (presumably associated mainly with secretory products) from the cytoplasmic label (presumably associated with nonsecretory proteins). (c) the specific activity of immature secretory granules was much greater than previously appreciated; at 1 h postpulse it was greater than 200 times that of the adjacent Golgi complex cisternae. This large dynamic range in observed grain density demonstrates the ability to effectively correct for radiation spread and thus to detect with great accuracy high concentration of label even from very small structures (20-100 nm) which constitute a small percentage (less than 1%) of the total cell area.

scholarly journals Clusterin is expressed in the anterior and intermediate lobes, but not in the posterior pituitary of sheep

1999 ◽  
Vol 23 (2) ◽  
pp. 199-208 ◽  
Author(s):  
JS Fleming ◽  
NM Hope ◽  
CJ Bolter
Keyword(s):  
Anterior Part ◽  
Hormone Secretion ◽  
In Situ Hybridisation ◽  
Cdna Probe ◽  
Northern Blotting ◽  
Secretory Cells ◽  
Pituitary Hormone ◽  
Pituitary Cells ◽  
Posterior Pituitary ◽  
Lipid Uptake

We have examined the expression of the ovine clusterin gene in the sheep pituitary gland, with the aim of determining its site of synthesis in this tissue. Northern blotting analysis of extracted polyadenylated RNA, using a (32)P-labelled rat clusterin cDNA probe, detected the greatest amounts of clusterin mRNA in the anterior part of dissected pituitary glands. In situ hybridisation studies showed clusterin mRNA in anterior and intermediate pituitary cells, with lower amounts in vascular endothelium and posterior pituicytes. Clusterin protein, detected by immunohistochemistry, was observed in some single secretory cells, within the capillary lumen and in cells around capillaries in the anterior and intermediate lobes, but no immunoreactivity was observed in posterior pituitary tissue. The pattern of clusterin expression in anterior and intermediate pituitary cells suggests possible roles for the protein in secretory cell turnover and/or hormone secretion or lipid uptake. Clusterin does not appear to be involved in ovine posterior pituitary hormone neurosecretion.

Visfatin and resistin in gonadotroph cells: expression, regulation of LH secretion and signalling pathways

2017 ◽  
Vol 29 (12) ◽  
pp. 2479 ◽  
Author(s):  
Virginie Maillard ◽  
Sébastien Elis ◽  
Alice Desmarchais ◽  
Céline Hivelin ◽  
Lionel Lardic ◽  
...  
Keyword(s):  
Signalling Pathways ◽  
Pituitary Cells ◽  
Extracellular Signal Regulated Kinase ◽  
Extracellular Signal ◽  
Mrna And Protein Expression ◽  
Mouse Pituitary ◽  
Amp Activated Protein Kinase ◽  
Lh Secretion ◽  
Resistin Mrna

Visfatin and resistin appear to interfere with reproduction in the gonads, but their potential action at the hypothalamic–pituitary level is not yet known. The aim of the present study was to investigate the mRNA and protein expression of these adipokines in murine gonadotroph cells and to analyse the effects of different concentrations of recombinant mouse visfatin and resistin (0.01, 0.1, 1 and 10 ng mL−1) on LH secretion and signalling pathways in LβT2 cells and/or in primary female mouse pituitary cells. Both visfatin and resistin mRNA and protein were found in vivo in gonadotroph cells. In contrast with resistin, the primary tissue source of visfatin in the mouse was the skeletal muscle, and not adipose tissue. Visfatin and resistin both decreased LH secretion from LβT2 cells after 24 h exposure of cells (P < 0.03). These results were confirmed for resistin in primary cell culture (P < 0.05). Both visfatin (1 ng mL−1) and resistin (1 ng mL−1) increased AMP-activated protein kinase α phosphorylation in LβT2 cells after 5 or 10 min treatment, up to 60 min (P < 0.04). Extracellular signal-regulated kinase 1/2 phosphorylation was transiently increased only after 5 min resistin (1 ng mL−1) treatment (P < 0.01). In conclusion, visfatin and resistin are expressed in gonadotroph cells and they may affect mouse female fertility by regulating LH secretion at the level of the pituitary.

Three-dimensional architecture of Golgi apparatus in the hormone secretory cell

1991 ◽  
Vol 49 ◽  
pp. 252-253
Author(s):  
S. Tai ◽  
R.M. Albrecht
Keyword(s):  
Golgi Apparatus ◽  
Golgi Complex ◽  
Secretory Cell ◽  
Secretory Granules ◽  
Three Dimensional ◽  
Cell Types ◽  
Pituitary Cells ◽  
Golgi Stack ◽  
Secretory Products ◽  
Cell Fractions

The Golgi apparatus plays an important role in the process of packaging and sorting of secretory granules in endocrine and exocrine cells. The intra Golgi site for concentrating secretory materials, packaging, and sorting the secretory granules has been widely studied using cytochemical, immunocytochemical and biochemical methods on cells and cell fractions. It is generally accepted that the secretory products fo How the cis to trans pathway across the Golgi stack. Within the Golgi complex, secretory products appear to be concentrated in the dilated rims of the trans-most cisternae which are associated with the formation of secretory granules. In pituitary cells the organization of the Golgi apparatus is not as regular as that described for many other cell types. The cisternae of different Golgi stacks are irregular in size and shape. The cis-trans arrangement is not in a definitive orientation.

scholarly journals THE FINE STRUCTURE OF BRUNNER'S GLANDS IN THE MOUSE

1965 ◽  
Vol 25 (3) ◽  
pp. 563-576 ◽  
Author(s):  
Daniel S. Friend
Keyword(s):  
Golgi Complex ◽  
Secretory Granules ◽  
Structural Features ◽  
Surface Epithelium ◽  
Secretory Cells ◽  
Brunner's Glands ◽  
Brunner’S Glands ◽  
Submucosal Glands ◽  
Glandular Cells ◽  
Cytological Characteristics

Examined with the electron microscope, the secretory cells of the submucosal glands of Brunner in the mouse present a curious combination of the fine-structural features of both serous and mucus-secreting cells. The cells have numerous mitochondria, abundant basal ergastoplasm, dense secretory granules that bear a superficial resemblance to pancreatic zymogen granules, and an unusually extensive Golgi apparatus. The prominence of the lamellar, vesicular, and vacuolar elements of the Golgi complex facilitates detailed observation of these components. More evident than in other glandular cells, aggregates of small vesicles appear to represent the transitional elements and are vehicles for transport of the product between the ergastoplasm and the Golgi complex. The numerous vesicular evaginations of smooth-surfaced regions on cisternae of the rough-surfaced endoplasmic reticulum and accumulations of innumerable vesicles of similar size in the area between the nearest profiles of the ergastoplasm and the Golgi complex support this contention. The cytological characteristics and physiologic properties of Brunner's glands in various species are discussed briefly. It is concluded that the submucosal glands of the mouse are excellent material for exploration of the ultrastructural correlates of both protein and carbohydrate secretion, and it is suggested that their secretion may have functions other than those generally attributed to them, namely, chemical and mechanical protection of the duodenal surface epithelium.

Regulation of gonadotropin secretion in the anterior pituitary

1981 ◽  
Vol 296 (1080) ◽  
pp. 73-81 ◽  
Keyword(s):  
Secretory Granules ◽  
Protein A ◽  
Gnrh Receptor ◽  
Pituitary Cells ◽  
Gonadotropin Secretion ◽  
Receptor Aggregation ◽  
Receptor Sites ◽  
Specific Antisera ◽  
Ultrathin Frozen Sections

Studies on the regulation of gonadotropin secretion in dissociated pituitary cell cultures are described. Initial studies employing a ferritin-labelled analogue of gonadotropin hormone releasing hormone (GnRH) to localize its receptor sites on the gonadotropin cell surface showed that while these receptor sites initially have a random monodisperse distribution, binding of the ligand causes coarse aggregation and internalization of the GnRH receptor. These events are not due to the multivalency of the ligand and probably reflect redistributive events in vivo . By using an octapeptide analogue GnRH that binds to the GnRH receptor but lacks gonadotropin releasing activity in conjunction with sequence-specific antisera it is shown that antibodies that bind the octapeptide can induce the octapeptide to release gonadotropin. These data suggest that receptor aggregation is important in GnRH stimulation. Finally immunocytochemical studies are described in which golg-protein-A-antibody complexes are used to identify gonadotropins on ultrathin frozen sections of porcine pituitary cells. These studies indicate that in porcine gonadotropin cells the majority of the secretory granules contain both luteinizing hormone and follicle-stimulating hormone.

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