Oogenesis in Dacus tryoni (Frogg.) (Diptera: Trypetidae)

1965 ◽  
Vol 13 (3) ◽  
pp. 423 ◽  
Author(s):  
DT Anderson ◽  
GC Lyford
Keyword(s):  
Lipid Droplets ◽  
Follicle Cells ◽  
Follicular Epithelium ◽  
Vitelline Membrane ◽  
Nurse Cells ◽  
Border Cells ◽  
Positive Material ◽  
Polytene Nuclei

Oogenesis in D. tryoni is typical of cyclorrhaphous Diptera. The ovariolar germarium produces a linear succession of 16-cell cysts enclosed by follicle cells. The cells of a cyst are interconnected by cytoplasmic canals and differentiate as 15 nurse cells and a posterior oocyte. Previtellogenesis occupies 3 days, vitellogenesis 1 day. The oocyte grows slowly during previtellogenesis, with little differentiation, rapidly during vitellogenesis, when protein and fatty yolk deposition, axial differentiation, and nuclear breakdown to first maturation metaphase, take place. The nurse cells grow rapidly during previtellogenesis and early vitellogenesis, developing large polytene nuclei and RNA-rich cytoplasm, and pour an RNA-rich nutrient stream into the oocyte during early vitellogenesis. The stream also contains P.A.S.-positive material, lipid droplets, possibly protein precursors, and nucleotides. Later, the nurse cells degenerate. Both growth and degeneration of the nurse cells are polarized, the posterior cells leading the more anterior cells. The follicular epithelium, cuboidal during previtellogenesis, differentiates as columnar around the oocyte, squamous outside the nurse cells, and anteriorly as border cells which migrate between the nurse cells to the anterior end of the oocyte. Late in vitellogenesis, the follicular epithelium secretes the chorion and vitelline membrane. It is not yet possible to discern in oogenesis the establishment in the oocyte of the prepattern essential for normal epigenesis.

An ultrastructural study of ovarian development in the otu7 mutant of Drosophila melanogaster

1984 ◽  
Vol 67 (1) ◽  
pp. 87-119
Author(s):  
D.L. Bishop ◽  
R.C. King
Keyword(s):  
Polytene Chromosomes ◽  
Vital Role ◽  
Follicle Cells ◽  
Vitelline Membrane ◽  
Nurse Cells ◽  
Border Cells ◽  
Stage Of Development ◽  
Ring Canals ◽  
Egg Chambers ◽  
Reduced Rate

Females homozygous for the otu7 allele produce ovarian tumours, as well as egg chambers that reach a relatively late stage of development. Mutant ovarian nurse cells contain giant polytene chromosomes. These are transcriptionally active, and RNA is transported to the oocyte through ring canals, although at reduced rate. Vitellogenic oocytes are endocytotically active. Protein (alpha yolk) spheres are formed, but glycogen (beta yolk) spheres were never seen in the ooplasm. Follicle cells migrate normally and secrete more vitelline membrane and chorion than is required to cover the slowly growing oocyte. Specialized follicle cells also secrete relatively normal dorsal appendages. The micropylar cone is secreted by another cluster of specialized follicle cells called border cells. These are out of phase with the oocyte, and the forming micropylar cone prevents the nurse cells from passing the remainder of their cytoplasm to the oocyte. The result is a morphologically abnormal chamber blocked at the p-12 stage. Sections through the micropylar cone of a p-12 chamber demonstrated that one of the border cells formed a projection containing a bundle of microtubules. Secretions of the border cells were deposited against this tube, which later degenerates or is withdrawn. Normally this results in a canal, the micropyle, through which the sperm enters the egg. The slowed growth of the mutant oocyte presumably results from a defect in the transport of fluids or charged molecules to it, and the otu+ gene is therefore believed to play a vital role in this process.

Differentiation within the gonads of Drosophila revealed by immunofluorescence

Development ◽  
1981 ◽  
Vol 63 (1) ◽  
pp. 233-242
Author(s):  
Danny L. Brower ◽  
R. J. Smith ◽  
Michael Wilcox
Keyword(s):  
Epithelial Cells ◽  
Hybrid Cell ◽  
Proximal Part ◽  
Follicular Epithelium ◽  
Follicle Development ◽  
Nurse Cells ◽  
Border Cells ◽  
Anterior Pole ◽  
Posterior Pair ◽  
Adult Ovary

The antibody produced by the hybrid cell line DA.1B6 binds to the diploid epithelial cells of Drosophila. In this paper, we describe the immunofluorescence-binding pattern of the antibody to the gonads. A bright sheath of fluorescence extends from the seminal vesicle onto the most proximal part of the adult testis. The only other significant binding to the organ is to the apical cells of the germinal proliferation centre, which fluoresce brightly in testes from adults and from third instar larvae. In the adult ovary, there is strong binding to the cells of the follicular epithelium, although this binding is reduced in the latter stages of follicle development. Soon after the formation of a follicle, a pair of epithelial cells at each pole of the follicle can be seen to fluoresce much more brightly than the other cells. This early differentiation is reflected in the morphogenetic behaviour of these polar cells as the follicle develops. The anterior pair are among the ‘border cells’ which migrate between the nurse cells to the anterior pole of the developing oocyte; and, when the follicular epithelium around the oocyte becomes columnar, the posterior pair of cells do not elongate as much as the surrounding cells.

scholarly journals PROTEIN UPTAKE IN THE OOCYTES OF THE CECROPIA MOTH

1965 ◽  
Vol 26 (1) ◽  
pp. 49-62 ◽  
Author(s):  
Barbara Stay
Keyword(s):  
Electron Microscope ◽  
Outer Surface ◽  
Dense Material ◽  
Follicle Cells ◽  
Follicular Epithelium ◽  
Vitelline Membrane ◽  
Blood Protein ◽  
Free Access ◽  
Structural Modifications ◽  
Oocyte Membrane

The formation of yolk spheres in the oocyte of the cecropia moth, Hyalophora cecropia (L.), is known immunologically to result largely from uptake of a sex-limited blood protein. Recent electron microscope analyses of insect and other animal oocytes have demonstrated fine structural configurations consistent with uptake of proteins by pinocytosis. An electron microscope analysis of the cecropia ovary confirms the presence of similar structural modifications. With the exception of two apparently amorphous layers, the basement lamella on the outer surface of the follicular epithelium and the vitelline membrane on the inner, there is free access of blood to the oocyte surface between follicle cells. Dense material is found in the interfollicular cell space and adsorbed to the outer surface of the much folded oocyte membrane. Pits in the oocyte membrane and vesicles immediately under it are lined with the same dense material not unlike the yolk spheres in appearance. Introduction of ferritin into the blood of a developing cecropia moth and its localization adsorbed to the surface of the oocyte, and within the vesicles and yolk spheres of the oocyte cortex, is experimental evidence that the structural modifications of the oocyte cortex represent stages in the pinocytosis of blood proteins which arrive at the oocyte surface largely by an intercellular route. Small tubules attached to the yolk spheres are provisionally interpreted as a manifestation of oocyte-synthesized protein being contributed to the yolk spheres.

The eggshell of Drosophila melanogaster. V. Structure and morphogenesis of the micropylar apparatus

1986 ◽  
Vol 64 (11) ◽  
pp. 2509-2519 ◽  
Author(s):  
Flora E. Zarani ◽  
Lukas H. Margaritis
Keyword(s):  
Drosophila Melanogaster ◽  
Outer Part ◽  
Follicle Cell ◽  
Follicle Cells ◽  
Vitelline Membrane ◽  
Mature Stage ◽  
Border Cells ◽  
Border Cell ◽  
Paracrystalline Structure ◽  
Cell Subpopulations

The micropylar apparatus in Drosophila melanogaster consists of two parts. The inner part is a protrusion of vitelline membrane, whereas the outer part is a chorionic protrusion containing a canal, through which the spermatozoon enters. In the formation of the micropylar apparatus two follicle cell subpopulations are involved: the border cells, i.e., a group of 9 follicle cells, and the peripheral cells (about 36 cells). The morphogenesis of the micropyle starts at stage 10B, when the border cells secrete the paracrystalline region of the vitelline membrane. The micropylar canal (length 7 μm, diameter 0.7 μm) and the pocket that penetrates within the paracrystalline structure are moulded by two border cell projections, full of microtubules. The formation of the micropyle terminates at stage 14B, when its chorionic part is completed and the border cell projections degenerate. The structure of the micropyle in fertilized and unfertilized laid eggs differs from the mature (stage 14B) egg in that the vitelline membrane is modified and appears homogeneous as in the rest of the eggshell. These transformations seem to be unrelated to sperm entry.

Two actions of juvenile hormone on the follicle cells of Rhodnius prolixus Stål

1975 ◽  
Vol 53 (8) ◽  
pp. 1187-1188 ◽  
Author(s):  
Randa Abu-Hakima ◽  
K. G. Davey
Keyword(s):  
Juvenile Hormone ◽  
Developmental Stages ◽  
Normal Animal ◽  
Rhodnius Prolixus ◽  
Follicle Cells ◽  
Follicular Epithelium ◽  
Intercellular Spaces

The follicular epithelium of vitellogenic oocytes from allatectomized females of Rhodnius fails to develop large intercellular spaces when exposed to juvenile hormone (JH) in vitro. This suggests that in the normal animal, the follicle cells require JH at two developmental stages. Differentiation of the cells in the presence of JH represents one requirement, and only those cells which have undergone this initial priming are fully competent to exhibit the second response, the development of intercellular spaces.

The extracellular electrical current pattern and its variability in vitellogenic Drosophila follicles

1986 ◽  
Vol 81 (1) ◽  
pp. 189-206 ◽  
Author(s):  
J. Bohrmann ◽  
A. Dorn ◽  
K. Sander ◽  
H. Gutzeit
Keyword(s):  
Juvenile Hormone ◽  
Current Density ◽  
Developmental Stages ◽  
Electrical Current ◽  
Posterior Pole ◽  
The Other ◽  
Follicular Epithelium ◽  
Nurse Cells ◽  
Vibrating Probe ◽  
Current Pattern

We determined the extracellular electrical current pattern around Drosophila follicles at different developmental stages (7–14) with a vibrating probe. At most stages a characteristic pattern can be recognized: current leaves near the oocyte end of the follicle and enters at the nurse cells. Only at late vitellogenic stages was an inward-directed current located at the posterior pole of many follicles. Most striking was the observed heterogeneity both in current pattern and in current density between follicles of the same stage. Different media (changed osmolarity or pH, addition of cytoskeletal inhibitors or juvenile hormone) were tested for their effects on extrafollicular currents. The current density was consistently influenced by the osmolarity of the medium but not by the other parameters tested. Denuded nurse cells (follicular epithelium locally stripped off) show current influx, while an accidentally denuded oocyte produced no current. Our results show that individual follicles may be electrophysiologically different, though their uniform differentiation during vitellogenesis does not reflect such heterogeneity.

scholarly journals Apical, Lateral, and Basal Polarization Cues Contribute to the Development of the Follicular Epithelium during Drosophila Oogenesis

2000 ◽  
Vol 151 (4) ◽  
pp. 891-904 ◽  
Author(s):  
Guy Tanentzapf ◽  
Christian Smith ◽  
Jane McGlade ◽  
Ulrich Tepass
Keyword(s):  
Apical Membrane ◽  
Pdz Domain ◽  
Basal Membrane ◽  
Follicle Cells ◽  
Follicular Epithelium ◽  
Epithelial Surface ◽  
Mosaic Analysis ◽  
Spectrin Cytoskeleton ◽  
Surface Domains ◽  
Mesenchymal Epithelial Transition

Analysis of the mechanisms that control epithelial polarization has revealed that cues for polarization are mediated by transmembrane proteins that operate at the apical, lateral, or basal surface of epithelial cells. Whereas for any given epithelial cell type only one or two polarization systems have been identified to date, we report here that the follicular epithelium in Drosophila ovaries uses three different polarization mechanisms, each operating at one of the three main epithelial surface domains. The follicular epithelium arises through a mesenchymal–epithelial transition. Contact with the basement membrane provides an initial polarization cue that leads to the formation of a basal membrane domain. Moreover, we use mosaic analysis to show that Crumbs (Crb) is required for the formation and maintenance of the follicular epithelium. Crb localizes to the apical membrane of follicle cells that is in contact with germline cells. Contact to the germline is required for the accumulation of Crb in follicle cells. Discs Lost (Dlt), a cytoplasmic PDZ domain protein that was shown to interact with the cytoplasmic tail of Crb, overlaps precisely in its distribution with Crb, as shown by immunoelectron microscopy. Crb localization depends on Dlt, whereas Dlt uses Crb-dependent and -independent mechanisms for apical targeting. Finally, we show that the cadherin–catenin complex is not required for the formation of the follicular epithelium, but only for its maintenance. Loss of cadherin-based adherens junctions caused by armadillo (β-catenin) mutations results in a disruption of the lateral spectrin and actin cytoskeleton. Also Crb and the apical spectrin cytoskeleton are lost from armadillo mutant follicle cells. Together with previous data showing that Crb is required for the formation of a zonula adherens, these findings indicate a mutual dependency of apical and lateral polarization mechanisms.

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.

The endocycle controls nurse cell polytene chromosome structure during Drosophila oogenesis

Development ◽  
1999 ◽  
Vol 126 (2) ◽  
pp. 293-303 ◽  
Author(s):  
K.J. Dej ◽  
A.C. Spradling
Keyword(s):  
Polytene Chromosome ◽  
Nurse Cell ◽  
Chromosome Structure ◽  
Polytene Chromosomes ◽  
S Phase ◽  
Nurse Cells ◽  
Chromosome Behavior ◽  
M Phase ◽  
Diploid Cells ◽  
Polytene Nuclei

Polytene chromosomes exhibit intricate higher order chromatin structure that is easily visualized due to their precisely aligned component strands. However, it remains unclear if the same factors determine chromatin organization in polyploid and diploid cells. We have analyzed one such factor, the cell cycle, by studying changes in Drosophila nurse cell chromosomes throughout the 10 to 12 endocycles of oogenesis. We find that nurse cells undergo three distinct types of endocycle whose parameters are correlated with chromosome behavior. The first four endocycles support complete DNA replication; poorly banded polytene euchromatin progressively condenses during the late S phases to produce blob-like chromosomes. During the unique fifth endocycle, an incomplete late S phase is followed by a mitosis-like state during which the 64C chromosomes dissociate into 32 chromatid pairs held together by unreplicated regions. All the subsequent endocycles lack any late S phase; during these cycles a new polytene chromosome grows from each 2C chromatid pair to generate 32-ploid polytene nuclei. These observations suggest that euchromatin begins to condense during late S phase and that nurse cell polytene chromosome structure is controlled by regulating whether events characteristic of late S and M phase are incorporated or skipped within a given endocycle.

maelstrom is required for an early step in the establishment of Drosophila oocyte polarity: posterior localization of grk mRNA

Development ◽  
1997 ◽  
Vol 124 (22) ◽  
pp. 4661-4671 ◽  
Author(s):  
N.J. Clegg ◽  
D.M. Frost ◽  
M.K. Larkin ◽  
L. Subrahmanyan ◽  
Z. Bryant ◽  
...  
Keyword(s):  
Nurse Cell ◽  
Egf Receptor ◽  
Mrna Localization ◽  
Follicle Cells ◽  
Rna Transport ◽  
Nurse Cells ◽  
Loss Of Function ◽  
Cell Fates ◽  
Early Step ◽  
Novel Protein

We describe a mutant, maelstrom, that disrupts a previously unobserved step in mRNA localization within the early oocyte, distinct from nurse-cell-to-oocyte RNA transport. Mutations in maelstrom disturb the localization of mRNAs for Gurken (a ligand for the Drosophila Egf receptor), Oskar and Bicoid at the posterior of the developing (stage 3–6) oocyte. maelstrom mutants display phenotypes detected in gurken loss-of-function mutants: posterior follicle cells with anterior cell fates, bicoid mRNA localization at both poles of the stage 8 oocyte and ventralization of the eggshell. These data are consistent with the suggestion that early posterior localization of gurken mRNA is essential for activation of the Egf receptor pathway in posterior follicle cells. Posterior localization of mRNA in stage 3–6 oocytes could therefore be one of the earliest known steps in the establishment of oocyte polarity. The maelstrom gene encodes a novel protein that has a punctate distribution in the cytoplasm of the nurse cells and the oocyte until the protein disappears in stage 7 of oogenesis.

Sign in / Sign up

Export Citation Format

Share Document