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.

scholarly journals A Nano-Platform for in situ Investigations of Ovarian Follicles

2020 ◽  
Author(s):  
Jean M. Feugang ◽  
Ghassan Ishak ◽  
Matthew Eggert ◽  
Robert Arnold ◽  
Scott Willard ◽  
...  
Keyword(s):  
Real Time ◽  
Transvaginal Ultrasound ◽  
Follicle Cell ◽  
Ovarian Follicles ◽  
Follicle Cells ◽  
Reproductive Techniques ◽  
Cell Layers ◽  
Doxorubicin Delivery

Abstract Background: Despite the growing array of assisted reproductive techniques, there is still a lack of rapid, non-cytotoxic, and minimally invasive in situ approaches for further enhancements through cell targeting. Here we synthesized clinically relevant liposome nanoparticles for real-time cellular targeting and drug (doxorubicin) delivery, using pigs and mares as animal models. In Experiment 1, fluorescently labeled and doxorubicin-loaded (without fluorescent probe) liposomes were injected in cultured pig ovarian follicles to assess plasma membrane binding and intracellular doxorubicin delivery. In Experiment 2, fluorescent liposomes were in vivo injected into small and large ovarian follicles of living mares to assess their binding capability to follicular cells. Twenty-four hours post-injection, all cultured pig follicles were collected while mare samples (i.e., follicle wall fragments, granulosa cells and follicular fluids) were harvested through follicle wall biopsy (FWB), and follicle aspiration and flushing techniques using transvaginal ultrasound-guided approach.Results: All injected follicles were healthy and samples were subjected to fluorescence imaging before and after fixation. Findings revealed successful intrafollicular migration and binding of liposomes to all follicle cell layers (granulosa, theca interna, and theca externa) regardless of the follicle size. The intracellular delivery of doxorubicin was confirmed with the staining of nuclei of follicle cells. Conclusions: This study demonstrates the promising combination of the FWB technique and nanotechnology tools for real-time monitoring of intrafollicular treatment, follicular health and oocyte development, which in turn has the potential to help understand the mechanisms of ovulatory dysfunction and to select high-quatity oocytes for assisted reproduction techniques.

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.

scholarly journals Metabolism of the biologically active inositol phosphates Ins(1,4,5)P3 and Ins(1,3,4,5)P4 by ovarian follicles of Xenopus laevis

1990 ◽  
Vol 268 (1) ◽  
pp. 141-145 ◽  
Author(s):  
R P McIntosh ◽  
J E A McIntosh
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Xenopus Laevis ◽  
Inositol Phosphates ◽  
Follicle Cell ◽  
Ovarian Follicles ◽  
Biologically Active ◽  
Follicle Cells ◽  
Kinase C ◽  
Cell Layers

The metabolism of biologically active inositol phosphates in developed ovarian follicles from Xenopus laevis was investigated. Techniques used were microinjection of tracer into the intact oocyte coupled by gap junctions to follicle cells, as well as addition of tracer to homogenates of ovarian follicles and to homogenates of oocytes stripped of outer follicle-cell layers. Metabolism was similar to that previously described for other types of cell and tissue, with several unusual features. Homogenates of ovarian follicles were shown to contain an apparent 3′-phosphomonoesterase capable of converting [3H]Ins(1,3,4,5)P4 predominantly into a substance with h.p.l.c. elution characteristics of Ins(1,4,5)P3. In intact ovarian follicles, little Ins(1,4,5)P3 was formed but the esterase was activated by the phorbol ester activator of protein kinase C, PMA (phorbol 12-myristate 13-acetate; 60 nM), as well as by acetylcholine (200 microM). In follicle homogenates, this enzyme also appeared to be active in converting [3H]Ins(1,3,4)P3 into a substance eluting as Ins(1,4)P2. The apparent 3′-phosphomonoesterase activity was not inhibited by intracellular (or higher) levels of Mg2+. Although PMA activated this enzyme in intact oocytes relative to 5′-phosphomonoesterase activation, it did not enhance overall metabolism, in contrast with reports on other tissues. Compared with the processing of inositol phosphates injected into the intact follicle, homogenization in simulated intracellular medium appeared to alter the activity and/or accessibility of several enzymes. The metabolism of inositol phosphates appears to occur predominantly in the follicle cells surrounding the oocyte, as collagenase treatment followed by defolliculation greatly diminished the rates of metabolism of several inositol phosphates. The presence in Xenopus ovarian follicles of a 3′-phosphomonoesterase activated by protein kinase C in addition to the well-known 3′-kinase suggests that, by forming a reversible interconversion between Ins(1,4,5)P3 and Ins(1,3,4,5)P4, this tissue may have the potential to prolong stimulatory signals on binding of appropriate agonists to receptors.

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.

scholarly journals The role of integrins in Drosophila egg chamber morphogenesis

2019 ◽  
Author(s):  
Holly E. Lovegrove ◽  
Dan T. Bergstralh ◽  
Daniel St Johnston
Keyword(s):  
Basement Membrane ◽  
Cell Polarity ◽  
Cell Shape ◽  
Follicle Cell ◽  
Follicle Cells ◽  
Follicular Epithelium ◽  
Egg Chambers ◽  
Germline Cyst ◽  
Egg Chamber

AbstractA Drosophila egg chamber is comprised of a germline cyst surrounded by a tightly-organised epithelial monolayer, the follicular epithelium (FE). Loss of integrin function from the FE disrupts epithelial organisation at egg chamber termini, but the cause of this phenotype remains unclear. Here we show that the β-integrin Myospheroid (Mys) is only required during early oogenesis when the pre-follicle cells form the FE. mys mutants disrupt both the formation of a monolayered epithelium at egg chamber termini and the morphogenesis of the stalk between adjacent egg chambers, which develops through the intercalation of two rows of cells into a single-cell wide stalk. Secondary epithelia, like the FE, have been proposed to require adhesion to the basement membrane to polarise. However, Mys is not required for pre-follicle cell polarisation, as both follicle and stalk cells localise polarity factors correctly, despite being mispositioned. Instead, loss of integrins causes pre-follicle cells to basally constrict, detach from the basement membrane and become internalised. Thus, integrin function is dispensable for pre-follicle cell polarity but is required to maintain cellular organisation and cell shape during morphogenesis.

scholarly journals Apical Spectrin Is Essential for Epithelial Morphogenesis but Not Apicobasal Polarity in Drosophila

1999 ◽  
Vol 146 (5) ◽  
pp. 1075-1086 ◽  
Author(s):  
Daniela C. Zarnescu ◽  
Graham H. Thomas
Keyword(s):  
Cell Shape ◽  
Follicle Cell ◽  
Membrane Skeleton ◽  
Epithelial Morphogenesis ◽  
Follicle Cells ◽  
Direct Role ◽  
Apical Constriction ◽  
Border Cell ◽  
Apicobasal Polarity

Changes in cell shape and position drive morphogenesis in epithelia and depend on the polarized nature of its constituent cells. The spectrin-based membrane skeleton is thought to be a key player in the establishment and/or maintenance of cell shape and polarity. We report that apical βHeavy-spectrin (βH), a terminal web protein that is also associated with the zonula adherens, is essential for normal epithelial morphogenesis of the Drosophila follicle cell epithelium during oogenesis. Elimination of βH by the karst mutation prevents apical constriction of the follicle cells during mid-oogenesis, and is accompanied by a gross breakup of the zonula adherens. We also report that the integrity of the migratory border cell cluster, a group of anterior follicle cells that delaminates from the follicle epithelium, is disrupted. Elimination of βH prevents the stable recruitment of α-spectrin to the apical domain, but does not result in a loss of apicobasal polarity, as would be predicted from current models describing the role of spectrin in the establishment of cell polarity. These results demonstrate a direct role for apical (αβH)2-spectrin in epithelial morphogenesis driven by apical contraction, and suggest that apical and basolateral spectrin do not play identical roles in the generation of apicobasal polarity.

The oocyte of the domestic chicken shortly after hatching, studied by electron microscopy

Development ◽  
1966 ◽  
Vol 15 (3) ◽  
pp. 297-316
Author(s):  
M. L. Greenfield
Keyword(s):  
Electron Microscopy ◽  
Cell Membrane ◽  
Follicle Cell ◽  
Domestic Chicken ◽  
Follicle Cells ◽  
Golgi Bodies ◽  
New Type

The cytoplasm of oocytes is highly complex. This has been demonstrated by light-microscopists not only in birds but in most other classes of animals (see review by Raven, 1961), although the various authors have not always agreed as to the nature of the cytoplasmic components nor as to their significance. For instance, in birds it has often been reported that certain structures pass from the follicle cells into the oocyte, but these have been identified as Golgi bodies, as mitochondria or as lipid drops by different authors. Recently, however, it has been demonstrated by electron microscopy that in the oocytes of adult birds the structures are instead a new type of organelle formed by a modification of the follicle-cell membrane and they have been termed ‘lining bodies’ (Bellairs, 1964, 1965). The role of these structures is not understood and it is clear that more information is needed about them.

Role of spectrin in membrane fusion and in shape change of human erythrocyte ghost

1978 ◽  
Vol 36 (2) ◽  
pp. 328-329
Author(s):  
Hideo Hayashi ◽  
Yoshikazu Hirai ◽  
John T. Penniston
Keyword(s):  
Conformational Changes ◽  
Human Erythrocyte ◽  
Shape Change ◽  
Membrane Surface ◽  
Slight Modification ◽  
Active Role ◽  
Main Role ◽  
Bank Blood ◽  
Human Erythrocyte Ghost

Spectrin is a membrane associated protein most of which properties have been tentatively elucidated. A main role of the protein has been assumed to give a supporting structure to inside of the membrane. As reported previously, however, the isolated spectrin molecule underwent self assemble to form such as fibrous, meshwork, dispersed or aggregated arrangements depending upon the buffer suspended and was suggested to play an active role in the membrane conformational changes. In this study, the role of spectrin and actin was examined in terms of the molecular arrangements on the erythrocyte membrane surface with correlation to the functional states of the ghosts.Human erythrocyte ghosts were prepared from either freshly drawn or stocked bank blood by the method of Dodge et al with a slight modification as described before. Anti-spectrin antibody was raised against rabbit by injection of purified spectrin and partially purified.

The Role of Mitochondria in the Genesis of Neuroaxonal Dystrophy in the Brains of Aging Mice

1975 ◽  
Vol 33 ◽  
pp. 372-373
Author(s):  
J.E. Johnson
Keyword(s):  
Electron Microscopy ◽  
Present Report ◽  
Light And Electron Microscopy ◽  
Dorsal Column ◽  
Neuroaxonal Dystrophy ◽  
Nucleus Gracilis ◽  
Dystrophic Axons ◽  
The Brain ◽  
Nucleus Cuneatus

Although neuroaxonal dystrophy (NAD) has been examined by light and electron microscopy for years, the nature of the components in the dystrophic axons is not well understood. The present report examines nucleus gracilis and cuneatus (the dorsal column nuclei) in the brain stem of aging mice.Mice (C57BL/6J) were sacrificed by aldehyde perfusion at ages ranging from 3 months to 23 months. Several brain areas and parts of other organs were processed for electron microscopy.At 3 months of age, very little evidence of NAD can be discerned by light microscopy. At the EM level, a few axons are found to contain dystrophic material. By 23 months of age, the entire nucleus gracilis is filled with dystrophic axons. Much less NAD is seen in nucleus cuneatus by comparison. The most recurrent pattern of NAD is an enlarged profile, in the center of which is a mass of reticulated material (reticulated portion; or RP).

Mesophyll conductance: the leaf corridors for photosynthesis

2020 ◽  
Vol 48 (2) ◽  
pp. 429-439 ◽  
Author(s):  
Jorge Gago ◽  
Danilo M. Daloso ◽  
Marc Carriquí ◽  
Miquel Nadal ◽  
Melanie Morales ◽  
...  
Keyword(s):  
Molecular Mechanisms ◽  
Current Knowledge ◽  
Main Role ◽  
Mesophyll Conductance ◽  
Future Studies ◽  
Cell Structures ◽  
Leaf Tissues ◽  
Change Framework ◽  
Chloroplast Stroma

Besides stomata, the photosynthetic CO2 pathway also involves the transport of CO2 from the sub-stomatal air spaces inside to the carboxylation sites in the chloroplast stroma, where Rubisco is located. This pathway is far to be a simple and direct way, formed by series of consecutive barriers that the CO2 should cross to be finally assimilated in photosynthesis, known as the mesophyll conductance (gm). Therefore, the gm reflects the pathway through different air, water and biophysical barriers within the leaf tissues and cell structures. Currently, it is known that gm can impose the same level of limitation (or even higher depending of the conditions) to photosynthesis than the wider known stomata or biochemistry. In this mini-review, we are focused on each of the gm determinants to summarize the current knowledge on the mechanisms driving gm from anatomical to metabolic and biochemical perspectives. Special attention deserve the latest studies demonstrating the importance of the molecular mechanisms driving anatomical traits as cell wall and the chloroplast surface exposed to the mesophyll airspaces (Sc/S) that significantly constrain gm. However, even considering these recent discoveries, still is poorly understood the mechanisms about signaling pathways linking the environment a/biotic stressors with gm responses. Thus, considering the main role of gm as a major driver of the CO2 availability at the carboxylation sites, future studies into these aspects will help us to understand photosynthesis responses in a global change framework.

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