X-Ray Binary Stars and Ovarian Follicle Growth: Math Models in Astrophysics and Physiology

Mathematical modelling was used to investigate oxygen transport in the developing ovarian follicle. In contrast to previous findings, the results show that oxygen can reach the oocyte in large preantral follicles. This is largely due to the inclusion of fluid voidage in the model and improved estimates of oxygen diffusion coefficients through the granulosa. The results also demonstrate that preantral follicles will eventually reach a size beyond which further growth will result in the follicle becoming increasingly anoxic. The predicted size range at which this occurs is consistent with the size range at which antrum formation is observed in many mammals. This suggests that the antrum formation stage of follicular growth may be pivotal to the further development and ultimate fate of the follicle, and that antrum formation itself may represent a mechanism by which the follicle can overcome oxygen limitations. This was supported through extension of the model to the antral follicle, which showed that antrum formation can provide a way in which the follicle can continue to grow and yet avoid becoming hypoxic. The results of the model were consistent with observed follicle development.

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Involvement of hyaluronan synthesis in ovarian follicle growth in rats

Reproduction ◽

10.1530/rep-13-0464 ◽

2014 ◽

Vol 147 (2) ◽

pp. 189-197 ◽

Cited By ~ 11

Author(s):

Noriyuki Takahashi ◽

Wataru Tarumi ◽

Bunpei Ishizuka

Keyword(s):

Ovarian Follicle ◽

Primary Site ◽

Corpora Lutea ◽

Follicular Atresia ◽

Follicle Growth ◽

Adult Rats ◽

Antral Follicles ◽

Cell Layers ◽

Ha Synthase

Most of the previous studies on ovarian hyaluronan (HA) have focused on mature antral follicles or corpora lutea, but scarcely on small preantral follicles. Moreover, the origin of follicular HA is unknown. To clarify the localization of HA and its synthases in small growing follicles, involvement of HA in follicle growth, and gonadotropin regulation of HA synthase (Has) gene expression, in this study, perinatal, immature, and adult ovaries of Wistar-Imamichi rats were examined histologically and biochemically and byin vitrofollicle culture. HA was detected in the extracellular matrix of granulosa and theca cell layers of primary follicles and more advanced follicles. Ovarian HA accumulation ontogenetically started in the sex cords of perinatal rats, and its primary site shifted to the intrafollicular region of primary follicles within 5 days of birth. TheHas1–3mRNAs were expressed in the ovaries of perinatal, prepubertal, and adult rats, and the expression levels ofHas1andHas2genes were modulated during the estrous cycle in adult rats and following administration of exogenous gonadotropins in immature acyclic rats. TheHas1andHas2mRNAs were predominantly localized in the theca and granulosa cell layers of growing follicles respectively. Treatments with chemicals known to reduce ovarian HA synthesis induced follicular atresia. More directly, the addition ofStreptomyceshyaluronidase, which specifically degrades HA, induced the arrest of follicle growth in anin vitroculture system. These results indicate that gonadotropin-regulated HA synthesis is involved in normal follicle growth.

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Inhibition of Ovarian Follicle Growth by a Chemical Antiestrogen

Hormone Research ◽

10.1159/000179506 ◽

1982 ◽

Vol 16 (4) ◽

pp. 230-236 ◽

Cited By ~ 19

Author(s):

R. Nakano ◽

T. Nakayama ◽

M. Iwao

Keyword(s):

Ovarian Follicle ◽

Follicle Growth

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Oriented basement membrane fibrils provide a memory for F-actin planar polarization via the Dystrophin-Dystroglycan complex during tissue elongation

10.1101/591628 ◽

2019 ◽

Author(s):

Fabiana Cerqueira Campos ◽

Cynthia Dennis ◽

Hervé Alégot ◽

Cornelia Fritsch ◽

Adam Isabella ◽

...

Keyword(s):

Basement Membrane ◽

Ovarian Follicle ◽

Follicle Cell ◽

Autonomous Control ◽

Stress Fibers ◽

Follicle Growth ◽

Growth Promoting ◽

Fibers Orientation ◽

Open Question ◽

The Relationship

SummaryHow extracellular matrix participates to tissue morphogenesis is still an open question. In the Drosophila ovarian follicle, it has been proposed that after Fat2-dependent planar polarization of the follicle cell basal domain, oriented basement membrane (BM) fibrils and F-actin stress fibers constrain follicle growth, promoting its axial elongation. However, the relationship between BM fibrils and stress fibers and their respective impact on elongation are unclear. We found that Dystroglycan (Dg) and Dystrophin (Dys) are involved in BM fibril deposition. Moreover, they orient stress fibers, by acting locally and in parallel to Fat2. Nonetheless, Dg-Dys complex-mediated cell autonomous control of F-actin fibers orientation relies on the previous BM fibril deposition, indicating two distinct but interdependent functions. Thus, the Dg-Dys complex works as a critical organizer of the epithelial basal domain, regulating both F-actin and BM. Furthermore, BM fibrils act as a persistent cue for the orientation of stress fibers that are the main effector of elongation.

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Radio Emitting X-Ray Binary Stars

International Astronomical Union Colloquium ◽

10.1017/s0252921100039178 ◽

1996 ◽

Vol 158 ◽

pp. 371-374

Author(s):

R. E. Spencer

Keyword(s):

Black Hole ◽

Neutron Star ◽

Radio Emission ◽

Binary Stars ◽

X Ray ◽

Ss 433 ◽

Normal Star ◽

Large Numbers ◽

X Ray Binaries

Some of the most astrophysically interesting objects are found among the radio-emitting X-ray binary stars (REXRB). The class includes the well-studied objects such as SS 433, Cyg X-3 and Sco X-1. The recent discoveries of relativistic ejection of radio knots in the X-ray transients 1915+105 (Mirabel & Rodriguez 1994) and 1655–40 (Hjellming & Rupen 1995) well illustrate the extreme nature of some of these objects.X-ray binaries are semi-detached binary stars in which matter is transfered from a more or less normal star onto a neutron star or black hole. X-ray satellites have detected large numbers of these objects (193 in a recent catalogue by van Paradijs 1995). However only a small fraction of these are known to have radio emission (e.g. Hjellming 1988).

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Interpolation of Missing Part of Human Follicle Border on Ultrasonic B-Mode Image by Iterative Revision

Ultrasonic Imaging ◽

10.1177/016173460002200203 ◽

2000 ◽

Vol 22 (2) ◽

pp. 108-122

Author(s):

Y. Yamakoshi ◽

M. Takemoto ◽

N. Shinozuka

Keyword(s):

Ovarian Follicle ◽

A Priori ◽

Three Dimensional ◽

Closed Curve ◽

Smoothness Condition ◽

A Priori Information ◽

Follicle Growth ◽

Cross Sectional ◽

Geometrical Characteristics ◽

Priori Information

In clinical infertility treatments, assessment of ovarian follicle growth by ultrasonography is important. In order to measure the geometrical characteristics of the human follicle, such as the area of the cross-sectional image and the volume inside the follicle, a method based on manual tracing of the follicle contour from the ultrasonic B mode image is widely used. However, the observable ultrasonic B mode images are sometimes imperfect and some parts of the follicle border are missing due to the existence of the acoustic shadow. In this paper, a method that interpolates the missing part of the follicle border from the known part is proposed. This method uses a priori information of the follicle, which is usually known in actual cases: (1) the follicle's surface is so smooth that its border is assumed to be a smooth closed curve; and (2) the position of the follicle's center is roughly predicted in advance in the ultrasonic B-mode image. In the proposed method, the missing part of the human follicle border is interpolated from the known part by applying an iterative revision so as to satisfy the smoothness condition of the follicle. This method is also applied to three-dimensional image reconstruction of the human follicle.

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Exposure to Bisphenol A Inhibits Ovarian Follicle Growth and Hormone Production in the Mouse.

Biology of Reproduction ◽

10.1093/biolreprod/81.s1.639 ◽

2009 ◽

Vol 81 (Suppl_1) ◽

pp. 639-639

Author(s):

Jackye Peretz ◽

Tessie Paulose ◽

Maria Isabel Hernandez Ochoa ◽

Jodi Anne Flaws

Keyword(s):

Bisphenol A ◽

Ovarian Follicle ◽

Follicle Growth ◽

Hormone Production

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A stellar census in globular clusters with MUSE: A spectral catalogue of emission-line sources

Astronomy and Astrophysics ◽

10.1051/0004-6361/201936485 ◽

2019 ◽

Vol 631 ◽

pp. A118 ◽

Cited By ~ 7

Author(s):

Fabian Göttgens ◽

Tim-Oliver Husser ◽

Sebastian Kamann ◽

Stefan Dreizler ◽

Benjamin Giesers ◽

...

Keyword(s):

Emission Line ◽

Binary Stars ◽

Globular Clusters ◽

Cataclysmic Variables ◽

Variable Stars ◽

Emission Lines ◽

Data Set ◽

Stellar Spectra ◽

X Ray ◽

Emission Line Galaxies

Aims. Globular clusters produce many exotic stars due to a much higher frequency of dynamical interactions in their dense stellar environments. Some of these objects were observed together with several hundred thousand other stars in our MUSE survey of 26 Galactic globular clusters. Assuming that at least a few exotic stars have exotic spectra (i.e. spectra that contain emission lines), we can use this large spectroscopic data set of over a million stellar spectra as a blind survey to detect stellar exotica in globular clusters. Methods. To detect emission lines in each spectrum, we modelled the expected shape of an emission line as a Gaussian curve. This template was used for matched filtering on the differences between each observed 1D spectrum and its fitted spectral model. The spectra with the most significant detections of Hα emission are checked visually and cross-matched with published catalogues. Results. We find 156 stars with Hα emission, including several known cataclysmic variables (CV) and two new CVs, pulsating variable stars, eclipsing binary stars, the optical counterpart of a known black hole, several probable sub-subgiants and red stragglers, and 21 background emission-line galaxies. We find possible optical counterparts to 39 X-ray sources, as we detected Hα emission in several spectra of stars that are close to known positions of Chandra X-ray sources. This spectral catalogue can be used to supplement existing or future X-ray or radio observations with spectra of potential optical counterparts to classify the sources.

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