Occurrence of intercellular bridges between follicle epithelial cells in the ovary of Apis mellifica queens

1977 ◽  
Vol 24 (1) ◽  
pp. 195-202
Author(s):  
P.S. Ramamurty ◽  
W. Engels
Keyword(s):  
Epithelial Cells ◽  
Developmental Stages ◽  
Light And Electron Microscopy ◽  
Follicle Cell ◽  
Dense Material ◽  
Follicle Cells ◽  
Electron Dense Material ◽  
Intercellular Bridges ◽  
Additional Layer ◽  
Apis Mellifica

Hitherto unknown intercellular bridges or fusomes between the follicle epithelial cells investing the oocytes of Apis mellifica queens have been observed both with light and electron microscopy. Usually each follicle cell has 2–3 intercellular bridges. In surfacial paraffin sections, the intercellular bridges can be seen to connect a series of follicle cells which may be branching. The intercellular bridges lie close to the egg cortex and this position is relatively constant. The width of the fusomal ring canal varies in different developmental stages. In stages 3 and 4 of oogenesis, which are the main vitellogenic stages, the intercellular bridges measure 0-5 micron, while in stages 1 and 2 they have a diameter ranging from 1–5 to 3–5 micron. In these stages the intercellular bridges are provided with numerous transverse microfilaments which disappear later. The fusomal lips are thickened and consist of electron-dense material and an additional layer of less electron-dense material both inside and outside. Ribosomes flow across the bridge. The intercellular bridges may serve to synchronize the differentiation and functional activity of the follicle epithelium during the course of oogenesis.

Comparative Morphology of Intercellular Bridges Between Developing Germ Cells of the Ovary

1970 ◽  
Vol 28 ◽  
pp. 328-329
Author(s):  
J. R. Ruby ◽  
R. F. Dyer ◽  
R. G. Skalko ◽  
R. F. Gasser ◽  
E. P. Volpe
Keyword(s):  
Germ Cells ◽  
Rana Pipiens ◽  
Comparative Morphology ◽  
Dense Material ◽  
Individual Species ◽  
Microscope Examination ◽  
Electron Dense Material ◽  
Intercellular Bridges ◽  
Cytoplasmic Side ◽  
Intercellular Connections

An electron microscope examination of fetal ovaries has revealed that developing germ cells are connected by intercellular bridges. In this investigation several species have been studied including human, mouse, chicken, and tadpole (Rana pipiens). These studies demonstrate that intercellular connections are similar in morphology regardless of the species.Basically, all bridges are characterized by a band of electron-dense material on the cytoplasmic side of the tri-laminar membrane surrounding the connection (Fig.l). This membrane is continuous with the plasma membrane of the conjoined cells. The dense material, however, never extends beyond the limits of the bridge. Variations in the configuration of intercellular connections were noted in all ovaries studied. However, the bridges in each individual species usually exhibits one structural characteristic seldom found in the others. For example, bridges in the human ovary very often have large blebs projecting from the lateral borders whereas the sides of the connections in the mouse gonad merely demonstrate a slight convexity.

scholarly journals Drosophila insulin-like peptide 8 (DILP8) in ovarian follicle cells regulates ovulation and metabolism

2020 ◽  
Author(s):  
Sifang Liao ◽  
Dick R. Nässel
Keyword(s):  
Adult Female ◽  
Developmental Stages ◽  
Ovarian Follicle ◽  
Expression Patterns ◽  
Follicle Cell ◽  
Follicle Cells ◽  
Ovary Development ◽  
Peripheral Neurons ◽  
Efferent Neurons

AbstractIn Drosophila eight insulin-like peptides (DILP1-8) are encoded on separate genes. These DILPs are characterized by unique spatial and temporal expression patterns during the lifecycle. Whereas functions of several of the DILPs have been extensively investigated at different developmental stages, the role of DILP8 signaling is primarily known from larvae and pupae where it couples organ growth and developmental transitions. In adult female flies, a study showed that a specific set of neurons that express the DILP8 receptor, Lgr3, is involved in regulation of reproductive behavior. Here, we further investigated the expression of dilp8/DILP8 and Lgr3 in adult female flies and the functional role of DILP8 signaling. The only site where we found both dilp8 expression and DILP8 immunolabeling was in follicle cells of mature ovaries. Lgr3 expression was detected in numerous neurons in the brain and ventral nerve cord, a small set of peripheral neurons innervating the abdominal heart, as well as in a set of follicle cells close to the oviduct. Ovulation was affected in dilp8 mutants as well as after dilp8-RNAi using dilp8 and follicle cell Gal4 drivers. More eggs were retained in the ovaries and fewer were laid, indicating that DILP8 is important for ovulation. Our data suggest that DILP8 signals locally to Lgr3 expressing follicle cells as well as systemically to Lgr3 expressing efferent neurons in abdominal ganglia that innervate oviduct muscle. Thus, DILP8 may act at two targets to regulate ovulation: follicle cell rupture and oviduct contractions. Furthermore, we could show that manipulations of dilp8 expression affect food intake and starvation resistance. Possibly this reflects a feedback signaling between ovaries and the CNS that ensures nutrients for ovary development. In summary, it seems that DILP8 signaling in regulation of reproduction is an ancient function, conserved in relaxin signaling in mammals.

A targeted gene silencing technique shows that Drosophila myosin VI is required for egg chamber and imaginal disc morphogenesis

1999 ◽  
Vol 112 (21) ◽  
pp. 3677-3690 ◽  
Author(s):  
W. Deng ◽  
K. Leaper ◽  
M. Bownes
Keyword(s):  
Gene Silencing ◽  
Imaginal Disc ◽  
Developmental Stages ◽  
Expression System ◽  
Follicle Cell ◽  
Follicle Cells ◽  
Myosin Vi ◽  
Nurse Cells ◽  
Cell Shapes ◽  
Egg Chamber

We report that Drosophila unconventional myosin VI, encoded by Myosin heavy chain at 95F (Mhc95F), is required for both imaginal disc and egg chamber morphogenesis. During oogenesis, Mhc95F is expressed in migrating follicle cells, including the border cells, which migrate between the nurse cells to lie at the anterior of the oocyte; the columnar cells that migrate over the oocyte; the centripetal cells that migrate between the oocyte and nurse cells; and the dorsal-anterior follicle cells, which migrate to secrete the chorionic appendages. Its function during development has been studied using a targeted gene silencing technique, combining the Gal4-UAS targeted expression system and the antisense RNA technique. Antibody staining shows that the expression of myosin 95F is greatly decreased in follicle cells when antisense Mhc95F RNA is expressed. Interfering with expression of Drosophila myosin VI at various developmental stages frequently results in lethality. During metamorphosis it results in adult flies with malformed legs and wings, indicating that myosin VI is essential for imaginal disc morphogenesis. During oogenesis, abnormal follicle cell shapes and aberrant follicle cell migrations are observed when antisense Mhc95F is expressed in follicle cells during stages 9 to 10, suggesting that the Drosophila myosin VI is required for follicle cell epithelial morphogenesis.

Studies withBrugia pahangi. 14. Intrauterine development of the microfilaria and a comparison with other filarial species

1976 ◽  
Vol 50 (4) ◽  
pp. 251-257 ◽  
Author(s):  
Rosemary Rogers ◽  
D. S. Ellis ◽  
D. A. Denham
Keyword(s):  
Electron Microscopy ◽  
Light And Electron Microscopy ◽  
Uterine Wall ◽  
Dense Material ◽  
Intrauterine Development ◽  
Brugia Pahangi ◽  
Electron Dense Material ◽  
Large Numbers ◽  
Egg Shells ◽  
Egg Shell

ABSTRACTThe intrauterine development ofBrugia pahangiembryos was followed from after fertilization to birth, using light and electron microscopy. The origin and development of the sheath of the microfilaria and its Possible role in the nutrition of the developing embryo were particularly investigated. Comparisons were drawn with the intrauterine development of other filarial species. The egg shell of theB. pahangiembryo js distinct from the oolemma and forms the sheath of the microfilaria. It is suggested that the electron dense material released by cells of the uterine wall and passing along the channels between the egg shells of adjacent embryos is nutritive. The death of large numbers of developing embryos in the central uterine Jumen is probably caused by overcrowding as their size rapidly increases, leading to nutritional deficiency.

Ovulation and placentation in Botryllus schlosseri (Ascidiacea): an ultrastructural study

1987 ◽  
Vol 65 (5) ◽  
pp. 1181-1190 ◽  
Author(s):  
Giovanna Zaniolo ◽  
Paolo Burighel ◽  
Gianbruno Martinucci
Keyword(s):  
Light And Electron Microscopy ◽  
Follicle Cell ◽  
Follicle Cells ◽  
Main Role ◽  
Botryllus Schlosseri ◽  
Maternal Origin ◽  
Cell Layers ◽  
Test Cells ◽  
Vitelline Coat

The mode of ovulation and placentation was studied by light and electron microscopy in the ovoviviparous ascidian Botryllus schlosseri using colonies from the laboratory. The full-grown oocyte is surrounded by the outer and inner follicle cell layers, the acellular vitelline coat (chorion), and the test cells, and it is furnished with its own vesicular oviduct which is interposed between the egg and the atrial epithelium. In contrast to most ascidians, the outer follicle is thick and has an ultrastructure consistent with intense protein synthesis. At ovulation the outer follicle shows signs of involution where it contacts the oviduct. When the oviducal wall breaks and the egg moves through the oviduct, the outer follicle cells are discharged in the mantle to form a sort of corpus luteum. The egg remains hanging in the atrial chamber by means of a cuplike "placenta." The placental tissues are all of maternal origin, being derived from both the atrial and oviducal epithelia together with some of the inner follicle cells. These latter anchor to the oviducal epithelium by means of junctional spots and a filamentous cementing secretion. Our results suggest that the main role of the "placenta" is to attach the embryo to the parent, thus exposing it to the flow of seawater.

Role of M Cells and Macrophages in the Entrance of Mycobacterium paratuberculosis into Domes of Ileal Peyer's Patches in Calves

1988 ◽  
Vol 25 (2) ◽  
pp. 131-137 ◽  
Author(s):  
E. Momotani ◽  
D. L. Whipple ◽  
A. B. Thiermann ◽  
N. F. Cheville
Keyword(s):  
Electron Microscopy ◽  
Cross Section ◽  
Light And Electron Microscopy ◽  
Peyer's Patches ◽  
Dense Material ◽  
M Cells ◽  
Mycobacterium Paratuberculosis ◽  
Electron Dense Material ◽  
Acid Fast Bacilli

Ligated ileal loops of calves were inoculated with live and heat-killed Mycobacterium paratuberculosis and were examined by light and electron microscopy. At 5 hours after inoculation, acid-fast bacilli were in subepithelial macrophages, but not in M cells covering domes. At 20 hours, more than 50 acid-fast bacilli per cross section were in subepithelial macrophages in domes. Both living and heat-killed bacilli passed into domes. Addition of anti- M. paratuberculosis bovine scrum to the inoculum enhanced entry of bacteria into domes. By electron microscopy, intact bacilli with electron-transparent zones (peribacillary spaces) were in the supranuclear cytoplasm of M cells at 20 hours. M cells also contained vacuoles, including electron-dense material interpreted as degraded bacilli. Subepithelial and intraepithelial macrophages contained bacilli and degraded bacterial material in phagosomes. These results suggest that calf ileal M cells take up bacilli, and that subepithelial and intraepithelial macrophages secondarily accept bacilli or bacterial debris which are expelled from M cells.

Developmental stages of Cyclospora talpae in the liver and bile duct of the mole (Talpa europaea)

Parasitology ◽  
1990 ◽  
Vol 101 (3) ◽  
pp. 345-350 ◽  
Author(s):  
H. A. Mohamed ◽  
D. H. Molyneux
Keyword(s):  
Electron Microscopy ◽  
Life Cycle ◽  
Bile Duct ◽  
Epithelial Cells ◽  
Room Temperature ◽  
Mononuclear Cells ◽  
Developmental Stages ◽  
Light And Electron Microscopy ◽  
Ultra Structure ◽  
Talpa Europaea

SUMMARYThe completed life-cycle of Cyclospora talpae, an extra-intestinal coccidian (Apicomplexa) of the liver of the mole (Talpa europaea). is reported. Oocysts sporulated within 12–14 days at room temperature (20–22 °C). Both macro- and micro-gametocytes developed independently within the nucleus of epithelial cells lining the bile duct as demonstrated by both light and electron microscopy. Merogony was seen in the mononuclear cells in the capillary sinusoids of the liver. Merozoites showed the typical ultrastructural features of the Apicomplexa. The life-cycle of C. talpae and the ultra-structure of the gametogonic and merogonic stages are reported; the ultrastructure of the merozoites is reported as the first description of this stage for the genus Cyclospora.

Regulation of cell proliferation and patterning in Drosophila oogenesis by Hedgehog signaling

Development ◽  
2000 ◽  
Vol 127 (10) ◽  
pp. 2165-2176 ◽  
Author(s):  
Y. Zhang ◽  
D. Kalderon
Keyword(s):  
Hedgehog Signaling ◽  
Developmental Stages ◽  
Somatic Cells ◽  
Follicle Cell ◽  
Follicle Cells ◽  
Cell Lineages ◽  
Egg Chambers ◽  
Hh Signaling ◽  
Egg Chamber ◽  
Activity Loss

The localized expression of Hedgehog (Hh) at the extreme anterior of Drosophila ovarioles suggests that it might provide an asymmetric cue that patterns developing egg chambers along the anteroposterior axis. Ectopic or excessive Hh signaling disrupts egg chamber patterning dramatically through primary effects at two developmental stages. First, excess Hh signaling in somatic stem cells stimulates somatic cell over-proliferation. This likely disrupts the earliest interactions between somatic and germline cells and may account for the frequent mis-positioning of oocytes within egg chambers. Second, the initiation of the developmental programs of follicle cell lineages appears to be delayed by ectopic Hh signaling. This may account for the formation of ectopic polar cells, the extended proliferation of follicle cells and the defective differentiation of posterior follicle cells, which, in turn, disrupts polarity within the oocyte. Somatic cells in the ovary cannot proliferate normally in the absence of Hh or Smoothened activity. Loss of protein kinase A activity restores the proliferation of somatic cells in the absence of Hh activity and allows the formation of normally patterned ovarioles. Hence, localized Hh is not essential to direct egg chamber patterning.

Culture Techniques and Potential Research Applications of Human Hair Follicle Cells In Vitro

1985 ◽  
Vol 13 (1) ◽  
pp. 8-37
Author(s):  
A.J.M. Vermorken
Keyword(s):  
Epithelial Cells ◽  
Hair Follicle ◽  
Human Hair ◽  
Follicle Cell ◽  
Follicle Cells ◽  
Human Hair Follicle ◽  
Culture Techniques ◽  
Ready Availability ◽  
Skin Biopsies

Since 1980, when human hair follicle cells were cultured in vitro for the first time, a whole series of techniques have been developed that render hair follicle keratinocytes as easy to handle in culture as fibroblasts. As a consequence, one can conclude that the need for a method providing for the routine cultivation of easily obtainable human primary epithelial cells has now been met, and it may be expected that more and more workers will use hair follicle keratinocytes for studies that specifically require human epithelial cells. The ease of culture and the ready availability of material may encourage workers to consider human hair follicle cell culture before either animal models or cultures of cells derived from invasive skin biopsies.

Follicle cell bridges in the mosquito ovary: syncytia formation and bridge morphology

1978 ◽  
Vol 31 (1) ◽  
pp. 137-143
Author(s):  
A. Fiil
Keyword(s):  
Culex Pipiens ◽  
Follicle Cell ◽  
Follicle Cells ◽  
Nurse Cells ◽  
Serial Sections ◽  
Intercellular Bridges ◽  
Syncytia Formation

In the mosquito, Culex pipiens quinqefasciatus, the follicle cells enveloping the oocyte and the nurse cells are connected by intercellular bridges. The bridges are formed by incomplete cytokinesis, and they persist for more than 30 h after their formation. Reconstructions from serial sections showed that one syncytial group contained at least 32 cells; several cells continued outside the series. The cells in a syncytium divide asynchronously; this results in an irregular, branched orgainzation. The bridges may be either embedded in the cytoplasm of the cells, or they may form an extracellular connexion.

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