Histological changes in the ovary in relation to yolk deposition, allatectomy, and destruction of the median neurosecretory cells in Melanoplus sanguinipes

1976 ◽  
Vol 54 (2) ◽  
pp. 185-192 ◽  
Author(s):  
R. H. Elliott ◽  
C. Gillott
Keyword(s):  
Brush Border ◽  
Follicle Cell ◽  
Neurosecretory Cells ◽  
Corpora Allata ◽  
Follicle Cells ◽  
Follicular Epithelium ◽  
Uptake Mechanism ◽  
Histological Changes ◽  
Pinocytotic Vesicles ◽  
Median Neurosecretory Cells

Histological changes in the ovary during periods of yolk deposition suggest that differentiation of the follicular epithelium and oolemma is an essential prerequisite to the pinocytotic uptake of protein into the oocytes. Before vitellogenesis, intercellular spaces form between adjacent follicle cells, and a brush border appears along the oocyte surface. The presence of protein within these spaces and of elementary yolk spheres along the brush border suggests that protein reaches the oocyte by an intercellular route.Accumulation of yolk does not occur after allatectomy or median neurosecretory cell (mNSC) cautery. Allatectomy inhibits the differentiation of the follicle cells and oolemma. In contrast, after mNSC cautery, differentiation occurs but the pinocytotic vesicles pinched off from the oolemma are empty, indicating that the availability of yolk precursors, not the uptake mechanism, has been affected. In addition, the appearance of secretion in the lateral oviducts is prevented by allatectomy, but merely delayed by mNSC cautery. The findings indicate that the corpora allata, but not the mNSC, are the source of a gonadotropin that regulates follicle-cell differentiation and the development of secretion in the lateral oviducts.

Morphology and histology of the endocrine glands of Zootermopsis angusticollis Hagen (Isoptera)

1972 ◽  
Vol 50 (12) ◽  
pp. 1537-1547 ◽  
Author(s):  
Cedric Gillott ◽  
Chih-Ming Yin
Keyword(s):  
Cell Types ◽  
Cell Number ◽  
Neurosecretory Cells ◽  
Corpora Allata ◽  
Endocrine Glands ◽  
Histological Changes ◽  
Secretory Cycle ◽  
Zootermopsis Angusticollis ◽  
Primary Reproductives ◽  
Median Neurosecretory Cells

The morphology and histology of the endocrine glands of the various castes of Zootermopsis angmticollis were examined. Six types of median neurosecretory cells are distinguishable by size and stain affinity. No differences in the relative numbers of these cell types among castes can be seen. It is postulated that they may be different forms of the same cell during its synthetic and secretory cycle. Lateral neurosecretory cells can be identified consistently only in mature primary reproductives of both sexes. In the corpora cardiaca two types of cells occur; the fuchsinophilic cells are distributed generally whereas the cells that take up counterstain are restricted to the center of the gland. Intercellular neurosecretory cell product is found throughout the gland. No histological changes associated with the formation of particular castes were observed. The corpora allata (CA) vary in size and histological appearance according to caste but not sex. The CA of reproductives (primary and supplementary) and presoldiers are larger than those of juveniles of the same instar; those of soldiers are about the same size as those of the corresponding juvenile stage. These size increases are due mainly to changes in the ratio cytoplasmic diameter: nuclear diameter of the constituent cells and not to an increase in cell number. The H-shaped molt glands, which, as in other pterygote insects, disappear within a few days of the imaginal molt, are composed of a large prothoracic portion and a smaller cephalic ('ventral gland') portion extending anteriorly and dorsally. Histologically the two components are indistinguishable. Running through the glands are thin strands of muscle.

Juvenile hormone increases ouabain-binding capacity of microsomal preparations from vitellogenic follicle cells

1983 ◽  
Vol 61 (7) ◽  
pp. 826-831 ◽  
Author(s):  
T. T. Ilenchuk ◽  
K. G. Davey
Keyword(s):  
Juvenile Hormone ◽  
Binding Capacity ◽  
Follicle Cell ◽  
Follicle Cells ◽  
Follicular Epithelium ◽  
Curvilinear Relationship ◽  
Scatchard Analysis ◽  
Ouabain Binding ◽  
Binding Characteristics ◽  
Brain Microsomes

A comparison has been made of the effects of juvenile hormone (JH) on the binding characteristics for ouabain of microsomes prepared from brain and from cells of the follicular epithelium surrounding previtellogenic or vitellogenic oocytes in Rhodnius. JH has no effect on the binding of ouabain to brain microsomes and decreases the Kd, but does not alter the Bmax for previtellogenic follicle cells. For vitellogenic follicle cells, Scatchard analysis reveals a curvilinear relationship, which is interpreted as indicating that a new population of JH-sensitive ouabain-binding sites develops as the follicle cell enters vitellogenesis. These results are related to earlier data obtained on the effect of JH on ATPase activity, volume changes in isolated follicle cells, and the development of spaces between the cells of the follicular epithelium.

Patterning of the follicle cell epithelium along the anterior-posterior axis during Drosophila oogenesis

Development ◽  
1998 ◽  
Vol 125 (15) ◽  
pp. 2837-2846 ◽  
Author(s):  
A. Gonzalez-Reyes ◽  
D. St Johnston
Keyword(s):  
Follicle Cell ◽  
Cell Types ◽  
Follicle Cells ◽  
Follicular Epithelium ◽  
Axis Formation ◽  
Main Body ◽  
Drosophila Oogenesis ◽  
Egfr Mutant ◽  
Anterior Posterior ◽  
Anterior Posterior Axis

Gurken signals from the oocyte to the adjacent follicle cells twice during Drosophila oogenesis; first to induce posterior fate, thereby polarising the anterior-posterior axis of the future embryo and then to induce dorsal fate and polarise the dorsal-ventral axis. Here we show that Gurken induces two different follicle cell fates because the follicle cells at the termini of the egg chamber differ in their competence to respond to Gurken from the main-body follicle cells in between. By removing the putative Gurken receptor, Egfr, in clones of cells, we show that Gurken signals directly to induce posterior fate in about 200 cells, defining a terminal competence domain that extends 10–11 cell diameters from the pole. Furthermore, small clones of Egfr mutant cells at the posterior interpret their position with respect to the pole and differentiate as the appropriate anterior cell type. Thus, the two terminal follicle cell populations contain a symmetric prepattern that is independent of Gurken signalling. These results suggest a three-step model for the anterior-posterior patterning of the follicular epithelium that subdivides this axis into at least five distinct cell types. Finally, we show that Notch plays a role in both the specification and patterning of the terminal follicle cells, providing a possible explanation for the defect in anterior-posterior axis formation caused by Notch and Delta mutants.

scholarly journals Establishment of dorsal-ventral polarity of theDrosophilaegg requirescapicuaaction in ovarian follicle cells

Development ◽  
2001 ◽  
Vol 128 (22) ◽  
pp. 4553-4562 ◽  
Author(s):  
Deborah J. Goff ◽  
Laura A. Nilson ◽  
Donald Morisato
Keyword(s):  
Target Genes ◽  
Nuclear Translocation ◽  
Ovarian Follicle ◽  
Growth Factor Receptor ◽  
Follicle Cell ◽  
Dorsal Side ◽  
Follicle Cells ◽  
Follicular Epithelium ◽  
Egfr Signaling ◽  
Cell Nuclei

The dorsal-ventral pattern of the Drosophila egg is established during oogenesis. Epidermal growth factor receptor (Egfr) signaling within the follicular epithelium is spatially regulated by the dorsally restricted distribution of its presumptive ligand, Gurken. As a consequence, pipe is transcribed in a broad ventral domain to initiate the Toll signaling pathway in the embryo, resulting in a gradient of Dorsal nuclear translocation. We show that expression of pipe RNA requires the action of fettucine (fet) in ovarian follicle cells. Loss of maternal fet activity produces a dorsalized eggshell and embryo. Although similar mutant phenotypes are observed with regulators of Egfr signaling, genetic analysis suggests that fet acts downstream of this event. The fet mutant phenotype is rescued by a transgene of capicua (cic), which encodes an HMG-box transcription factor. We show that Cic protein is initially expressed uniformly in ovarian follicle cell nuclei, and is subsequently downregulated on the dorsal side. Earlier studies described a requirement for cic in repressing zygotic target genes of both the torso and Toll pathways in the embryo. Our experiments reveal that cic controls dorsal-ventral patterning by regulating pipe expression in ovarian follicle cells, before its previously described role in interpreting the Dorsal gradient.

Protein Synthesis and Uptake by Isolated Cecropia Oocytes

1971 ◽  
Vol 8 (3) ◽  
pp. 735-750
Author(s):  
LUCY M. ANDERSON
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Perchloric Acid ◽  
Selection Process ◽  
Ovarian Follicle ◽  
Follicle Cell ◽  
Follicle Cells ◽  
Follicular Epithelium ◽  
Blood Proteins ◽  
Cell Product

A procedure has been developed for separating the oocytes and follicular epithelium-nurse cell complexes making up the vitellogenic ovarian follicle of the Cecropia moth. Both components remained viable during short-term in vitro incubation in female blood. Isolated epithelial cells were found by autoradiography to incorporate tritiated amino acids and to secrete a fixable, non-dialysable labelled material. Isolated oocytes incubated in a blood medium containing this tritiated, dialysed follicle cell product incorporated it in small cortical yolk bodies, presumably by pinocytosis. Quantitative perchloric acid-precipitation and scintillation counting indicated that the amount of labelled material incorporated by the oocytes increased with time. These results provide direct confirmation of a follicle contribution to the yolk. Isolated oocytes were also tested for their ability to incorporate labelled amino acids. Fixable label was observed autoradiographically throughout the oocyte cytoplasm, with the greatest concentration in the cortex, but little appeared in the yolk spheres. The amount of perchloric acid-precipitable amino acid in oocytes incubated in female blood increased with time for up to 2 h and then remained constant or decreased slightly. In medium that had been previously conditioned by follicle cells and dialysed, however, incorporation of labelled amino acid continued for at least 4 h. A possible interpretation of this result is that stimulation of pinocytosis by the epithelial cell products causes increased turnover of cell membrane and demands continued synthesis of new proteins. Labelled female blood proteins were not incorporated into yolk to an appreciable extent by isolated oocytes, even in the presence of follicle cell product. Perhaps extracellular preconcentration, as occurs in the intact follicle, is necessary for effective accrual of blood proteins. The female blood proteins did become associated with the oocyte cortex, however, and exhibited a higher affinity for the oocyte than male blood proteins. Thus preferential adsorption to the oocyte surface may be a component of the selection process in vitellogenesis.

Ectopic activation of torpedo/Egfr, a Drosophila receptor tyrosine kinase, dorsalizes both the eggshell and the embryo

Development ◽  
1997 ◽  
Vol 124 (19) ◽  
pp. 3871-3880 ◽  
Author(s):  
A.M. Queenan ◽  
A. Ghabrial ◽  
T. Schupbach
Keyword(s):  
Cell Fate ◽  
Growth Factor Receptor ◽  
Follicle Cell ◽  
Follicle Cells ◽  
Follicular Epithelium ◽  
Cell Fates ◽  
Egfr Activation ◽  
Egg Chamber ◽  
Anterior Posterior ◽  
Anterior Posterior Axis

The Drosophila gene torpedo/Egfr (top/Egfr) encodes a homolog of the vertebrate Epidermal Growth Factor receptor. This receptor is required several times during the life cycle of the fly for the transmisson of developmental cues. During oogenesis, Top/Egfr activation is required for the establishment of the dorsal/ventral axis of the egg and the embryo. To examine how ectopic Top/Egfr activation affects cell fate determination, we constructed an activated version of the protein. Expression of this activated form (lambda top) in the follicle cells of the ovary induces dorsal cell fates in both the follicular epithelium and the embryo. Different levels of expression resulted in different dorsal follicle cell fates. These dorsal cell fates were expanded in the anterior, but not the posterior, of the egg, even in cases where all the follicle cells covering the oocyte expressed lambda top. The expression of genes known to respond to top/Egfr activation, argos (aos), kekkon1 (kek 1) and rhomboid (rho), was also expanded in the presence of the lambda top construct. When lambda top was expressed in all the follicle cells covering the oocyte, kek 1 and argos expression was induced in follicle cells all along the anterior/posterior axis of the egg chamber. In contrast, rho RNA expression was only activated in the anterior of the egg chamber. These data indicate that the response to Top/Egfr signaling is regulated by an anterior/posterior prepattern in the follicle cells. Expression of lambda top in the entire follicular epithelium resulted in an embryo dorsalized along the entire anterior/posterior axis. Expression of lambda top in anterior or posterior subpopulations of follicle cells resulted in regionally autonomous dorsalization of the embryos. This result indicates that subpopulations of follicle cells along the anterior/posterior axis can respond to Top/Egfr activation independently of one another.

Changes in the protein concentration and volume of the haemolymph in relation to yolk deposition, ovariectomy, allatectomy, and cautery of the median neurosecretory cells in Melanoplus sanguinipes

1977 ◽  
Vol 55 (1) ◽  
pp. 97-103 ◽  
Author(s):  
R. H. Elliott ◽  
C. Gillott
Keyword(s):  
Protein Synthesis ◽  
Total Protein ◽  
Protein Concentration ◽  
Neurosecretory Cells ◽  
Corpora Allata ◽  
Total Protein Content ◽  
Concentration Increase ◽  
Protein Levels ◽  
Low Protein ◽  
Median Neurosecretory Cells

The protein concentration and volume of the haemolymph may change with no apparent relation to one another in normal, ovariectomized, allatectomized, and median-neurosecretorycell-cauterized (mNSC-cauterized) females. Therefore, protein levels in the haemolymph are more meaningfully expressed in terms of the total protein content. In normal females, fluctuations in the haemolymph volume tend to parallel changes in the protein concentration during the first and subsequent gonotrophic periods. However, significantly less protein accumulates during the latter periods. The suggestion that these fluctuations partly reflect changes in the vitellogenic requirements of the oocytes is supported by the finding that both the volume and protein concentration increase significantly after ovariectomy.Allatectomy or mNSC cautery prevents the normal accumulation of protein in the haemolymph. In allatectomized females, the slight increase in protein concentration is accompanied by a decline in haemolymph volume. Cautery of the mNSC, provided it is performed within 3 h of emergence, results in a low protein concentration but has no effect on the haemolymph volume. The observations are discussed in terms of the corpora allata and mNSC control of haemolymph protein synthesis.

The Corpus Allatum and Oogenesis in Rhodnius Prolixus (Stål.)

1972 ◽  
Vol 56 (1) ◽  
pp. 223-237
Author(s):  
G. E. PRATT ◽  
K. G. DAVEY
Keyword(s):  
Topical Application ◽  
Egg Production ◽  
Neurosecretory Cells ◽  
Corpus Allatum ◽  
Yolk Protein ◽  
Corpora Allata ◽  
Follicular Epithelium ◽  
High Doses ◽  
Dose Levels ◽  
Second Wave

1. Mated females lay more eggs than virgin females. They also oviposit earlier in the cycle, and at a higher rate, than virgins. 2. Mated females produce, slightly more than two oocytes per ovariole. Virgin females produce a little more than one oocyte per ovariole. The first wave of oogenesis proceeds at the same rate in mated and virgin females, whereas the second wave is inhibited in virgins. 3. The concentration of yolk protein in the haemolymph remains high for longer in virgins than in mated females. The inhibition of egg production during the second wave of oogenesis in virgins is thus not a consequence of a previous decline in yolk-protein titre. 4. Virgin females digest their blood meal more slowly than mated females. 5. The follicular epithelium of an oocyte in the second wave of oogenesis in a virgin shows sparsely scattered intercellular spaces, whereas that of an oocyte from the first wave exhibits the abundant spaces characteristic of a follicle from a mated female. 6. During the time when vitellogenesis is inhibited in virgins there is an accumulation of oocytes in the size range below that of activation. 7. The corpora allata of both mated and virgin females undergo a cycle of increase in size associated with the cycle of oogenesis. There are no differences which can be correlated with the differences in the activities of the ovaries of mated and virgin females. 8. Topical application of farnesyl methyl ether (FME) to decapitated mated females brings about egg development equivalent to that of virgin females. 9. Topical application of FME to virgin females results in the production of the number of eggs characteristic of mated females, but very high doses are necessary to achieve this. These dose levels also result in an increase in rate of oviposition. These effects of high doses of FME are abolished if the virgin females lack their neurosecretory cells. 10. It is concluded that the virgin inhibition of oogenesis results not from a deficiency of allatum hormone, but from the presence of an antigonadotropin released from ovaries which contain mature eggs.

scholarly journals Distribution of yolk polypeptides in the follicle cells during the differentiation of the follicular epithelium in Sarcophaga bullata egg follicles

Development ◽  
1987 ◽  
Vol 101 (1) ◽  
pp. 33-43
Author(s):  
J. Geysen ◽  
J. Cardoen ◽  
A. De Loof
Keyword(s):  
Rna Synthesis ◽  
Follicle Cell ◽  
In Vitro Translation ◽  
Follicle Cells ◽  
Follicular Epithelium ◽  
Current Pattern ◽  
Sarcophaga Bullata ◽  
Polypeptide Synthesis ◽  
Egg Follicles

In S. bullata, the ovaries contribute to the synthesis of yolk polypeptides. A specific antiserum for yolk polypeptides was used to visualize the presence of yolk polypeptides in the follicle cells during their differentiation. After vitellogenesis has started, all follicle cells contain yolk polypeptides. The squamous follicle cells covering the nurse cells and the border cells lose yolk polypeptides before mid-vitellogenesis, whereas the follicle cells over the oocyte contain yolk polypeptides until after late vitellogenesis. All follicle cells are immunonegative afterwards. In vitro translation of poly(A)+ RNA demonstrated that the presence of yolk polypeptide mRNA correlates well with follicle cell immunopositivity for yolk polypeptides. This suggests that the follicle cells synthesize the ovarian yolk polypeptides. Differences in cellular and nuclear morphology, total and poly(A)+ RNA synthesis and the rate of yolk polypeptide synthesis were shown to be correlated with the presence or absence of yolk polypeptides in the differentiating follicular epithelium. The possible relationship between these different aspects of follicle cell differentiation, follicle cell polyploidy and the extracellular current pattern around follicles are discussed.

Mosaic analyses reveal the function ofDrosophila Rasin embryonic dorsoventral patterning and dorsal follicle cell morphogenesis

Development ◽  
2002 ◽  
Vol 129 (9) ◽  
pp. 2209-2222 ◽  
Author(s):  
Karen E. James ◽  
Jennie B. Dorman ◽  
Celeste A. Berg
Keyword(s):  
Tyrosine Kinases ◽  
Growth Factor Receptor ◽  
Signal Transduction Pathway ◽  
Follicle Cell ◽  
Follicle Cells ◽  
Follicular Epithelium ◽  
Dorsoventral Patterning ◽  
Ras Pathway ◽  
Egg Chambers ◽  
Ras Signal Transduction

In Drosophila melanogaster, the Ras signal transduction pathway is the primary effector of receptor tyrosine kinases, which govern diverse developmental programs. During oogenesis, epidermal growth factor receptor signaling through the Ras pathway patterns the somatic follicular epithelium, establishing the dorsoventral asymmetry of eggshell and embryo. Analysis of follicle cell clones homozygous for a null allele of Ras demonstrates that Ras is required cell-autonomously to repress pipe transcription, the critical first step in embryonic dorsoventral patterning. The effects of aberrant pipe expression in Ras mosaic egg chambers can be ameliorated, however, by post-pipe patterning events, which salvage normal dorsoventral polarity in most embryos derived from egg chambers with dorsal Ras clones. The patterned follicular epithelium also determines the final shape of the eggshell, including the dorsal respiratory appendages, which are formed by the migration of two dorsolateral follicle cell populations. Confocal analyses of mosaic egg chambers demonstrate that Ras is required both cell- and non cell-autonomously for morphogenetic behaviors characteristic of dorsal follicle cell migration, and reveal a novel, Ras-dependent pattern of basal E-cadherin localization in dorsal midline follicle cells.

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