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 Secretions of the border cells were deposited against this tube, which later degenerates or is withdrawn.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.

scholarly journals INTERCELLULAR MIGRATION OF CENTRIOLES IN THE GERMARIUM OF DROSOPHILA MELANOGASTER

1970 ◽  
Vol 45 (2) ◽  
pp. 306-320 ◽  
Author(s):  
Anthony P. Mahowald ◽  
Joan M. Strassheim
Keyword(s):  
Follicle Cell ◽  
Cell Cluster ◽  
Follicle Cells ◽  
Oocyte Nucleus ◽  
Nurse Cells ◽  
Serial Sections ◽  
Cell Border ◽  
Ring Canals ◽  
Egg Chambers ◽  
Stage 1

A cluster of centrioles has been found in the early Drosophila oocyte. Since the oocyte is connected to 15 nurse cells by a system of intercellular bridges or ring canals, the possibility that the cluster of centrioles arose in the germarium from an intercellular migration of centrioles from the nurse cells to the oocyte was analyzed in serial sections for the electron microscope. Initially, all of the 16 cells of the future egg chambers possess centrioles, which are located in a juxtanuclear position. At the time the 16 cell cluster becomes arranged in a lens-shaped layer laterally across the germarium, the centrioles lose their juxtanuclear position and move towards the oocyte. By the time the 16 cell cluster of cells is surrounded by follicle cells (Stage 1), between 14 and 17 centrioles are found in the oocyte. Later, these centrioles become located between the oocyte nucleus and the follicle cell border and become aggregated into a cluster less than 1.5 µ in its largest dimension. The fate of these centrioles in the oocyte is not known. The fine structure of the germarium and the early oocyte is also described.

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.

Oocyte determination and the origin of polarity in Drosophila: the role of the spindle genes

Development ◽  
1997 ◽  
Vol 124 (24) ◽  
pp. 4927-4937 ◽  
Author(s):  
A. Gonzalez-Reyes ◽  
H. Elliott ◽  
D. St Johnston
Keyword(s):  
Symmetry Breaking ◽  
Germinal Vesicle ◽  
Follicle Cells ◽  
Axis Formation ◽  
Main Body ◽  
Nurse Cells ◽  
Egg Chambers ◽  
Anterior Posterior ◽  
Oocyte Selection

The two main body axes in Drosophila become polarised as a result of a series of symmetry-breaking steps during oogenesis. Two of the sixteen germline cells in each egg chamber develop as pro-oocytes, and the first asymmetry arises when one of these cells is selected to become the oocyte. Anterior-posterior polarity originates when the oocyte then comes to lie posterior to the nurse cells and signals through the Gurken/Egfr pathway to induce the adjacent follicle cells to adopt a posterior fate. This directs the movement of the germinal vesicle and associated gurken mRNA from the posterior to an anterior corner of the oocyte, where Gurken protein signals for a second time to induce the dorsal follicle cells, thereby polarising the dorsal-ventral axis. Here we describe a group of five genes, the spindle loci, which are required for each of these polarising events. spindle mutants inhibit the induction of both the posterior and dorsal follicle cells by disrupting the localisation and translation of gurken mRNA. Moreover, the oocyte often fails to reach the posterior of mutant egg chambers and differentiates abnormally. Finally, double mutants cause both pro-oocytes to develop as oocytes, by delaying the choice between these two cells. Thus, these mutants reveal a novel link between oocyte selection, oocyte positioning and axis formation in Drosophila, leading us to propose that the spindle genes act in a process that is common to several of these events.

scholarly journals Murder on the Ovarian Express: A Tale of Non-Autonomous Cell Death in the Drosophila Ovary

Cells ◽  
2021 ◽  
Vol 10 (6) ◽  
pp. 1454
Author(s):  
Diane Patricia Vig Lebo ◽  
Kimberly McCall
Keyword(s):  
Cell Death ◽  
Follicle Cells ◽  
Nurse Cells ◽  
Fine Line ◽  
Egg Chambers ◽  
Drosophila Ovary ◽  
Size And Structure

Throughout oogenesis, Drosophila egg chambers traverse the fine line between survival and death. After surviving the ten early and middle stages of oogenesis, egg chambers drastically change their size and structure to produce fully developed oocytes. The development of an oocyte comes at a cost, the price is the lives of the oocyte’s 15 siblings, the nurse cells. These nurse cells do not die of their own accord. Their death is dependent upon their neighbors—the stretch follicle cells. Stretch follicle cells are nonprofessional phagocytes that spend the final stages of oogenesis surrounding the nurse cells and subsequently forcing the nurse cells to give up everything for the sake of the oocyte. In this review, we provide an overview of cell death in the ovary, with a focus on recent findings concerning this phagocyte-dependent non-autonomous cell death.

Accessory Nuclei in Hymenopteran Oocytes

1972 ◽  
Vol 30 ◽  
pp. 120-121
Author(s):  
Surinder K. Aggarwal
Keyword(s):  
Linear Growth ◽  
Follicle Cells ◽  
Nurse Cells ◽  
Monomorium Pharaonis ◽  
Ring Canals ◽  
Accessory Nuclei ◽  
Dense Nucleus ◽  
Well Differentiated

The ovary of Monomorium pharaonis (Hymenoperta: Myrmicidae) consists of a group of ovarioles, each consisting of an anterior germarium region formed of some cells that are undifferentiated or are in the process of differentiation and a more posterior vitellarium region consisting of a series of well differentiated polytrophic chambers. Each polytrophic chamber consists of a complex of 28-31 nurse cells interconnected by ring canals to a single oocyte and surrounded by a layer of follicle cells. In each ovariole the polytrophic chambers are lined up in a linear growth fashion determined by the amount of yolk deposited in the oocyte. In the previtellogenic stages the oocyte can be easily distinguished from the rest of the nurse cells by a less electron dense nucleus with synaptinemal complexes and a less pronounced nucleolus (Fig. 1).

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.

Src64 is required for ovarian ring canal morphogenesis during Drosophila oogenesis

Development ◽  
1998 ◽  
Vol 125 (15) ◽  
pp. 2883-2892 ◽  
Author(s):  
G.S. Dodson ◽  
D.J. Guarnieri ◽  
M.A. Simon
Keyword(s):  
Tyrosine Phosphorylation ◽  
Cellular Proliferation ◽  
Src Family Kinases ◽  
Nurse Cells ◽  
Loss Of Function ◽  
Filamentous Actin ◽  
Ring Canal ◽  
Specific Product ◽  
Ring Canals ◽  
Egg Chambers

The Src family of protein tyrosine kinases have been implicated as important regulators of cellular proliferation, differentiation and function. In order to understand further the role of Src family kinases, we have generated loss-of-function mutations in Src64, one of two Src family kinases known in Drosophila melanogaster. Animals with reduced Src64 function develop normally and are fully viable. However, Src64 female flies have reduced fertility, which is associated with the incomplete transfer of cytoplasm from nurse cells to the developing oocyte. Analysis of Src64 egg chambers showed defects in the ring canals that interconnect the oocyte and its 15 associated nurse cells. Src64 ring canals fail to accumulate the high levels of tyrosine phosphorylation that are normally present. Despite the reduced tyrosine phosphorylation, known ring canal components such as filamentous actin, a ring canal-specific product of the hu-li tai shao gene, and the kelch protein localize properly. However, Src64 ring canals are reduced in size and frequently degenerate. These results indicate that Src64 is required for the proper growth and stability of the ovarian ring canals.

Apoptosis in late stage Drosophila nurse cells does not require genes within the H99 deficiency

Development ◽  
1998 ◽  
Vol 125 (6) ◽  
pp. 1075-1082 ◽  
Author(s):  
K. Foley ◽  
L. Cooley
Keyword(s):  
Dna Fragmentation ◽  
Late Stage ◽  
Expression Patterns ◽  
Nuclear Material ◽  
Nurse Cells ◽  
Wild Type ◽  
Negative Regulators ◽  
Egg Chambers ◽  
Positive Regulators ◽  
Egg Chamber

We have determined that nurse cells are cleared from the Drosophila egg chamber by apoptosis. DNA fragmentation begins in nurse cells at stage 12, following the completion of cytoplasm transfer from the nurse cells to the oocyte. During stage 13, nurse cells increasingly contain highly fragmented DNA and disappear from the egg chamber concomitantly with the formation of apoptotic vesicles containing highly fragmented nuclear material. In dumpless mutant egg chambers that fail to complete cytoplasm transport from the nurse cells, DNA fragmentation is markedly delayed and begins during stage 13, when the majority of cytoplasm is lost from the nurse cells. These data suggest the presence of cytoplasmic factors in nurse cells that inhibit the initiation of DNA fragmentation. In addition, we have examined the ovarian expression patterns of regulatory genes implicated in Drosophila apoptosis. The positive regulators, reaper (rpr), head involution defective (hid) and grim, as well as the negative regulators, DIAP1 and DIAP2, are transcribed during oogenesis. However, germline clones homozygous for the deficiency Df(3)H99, which deletes rpr, hid and grim, undergo oogenesis in a manner morphologically indistinguishable from wild type, indicating that genes within this region are not necessary for apoptosis in nurse cells.

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.

Sign in / Sign up

Export Citation Format

Share Document