Secretion of fibronectin by rat granulosa cells occurs primarily during early follicular development

The precise mechanism for the initiation of follicle growth and progression through the earliest stages of follicle development remains largely unknown. Activins play a role during early follicle development, and evidence suggests that the extracellular matrix plays a role during later stages of follicular growth. We investigated the role of activin-A and extracellular matrix in follicle growth initiation and early follicular development in the mouse ovary. Ovaries were collected from 5-day-old mice and cultured for 10 days on polylysine, collagen, or laminin in the presence or absence of recombinant human activin-A. Follicle density, indices of follicle growth initiation (primary:primordial follicle [PY:PD] and primary:total follicle [PY:TF] ratios), ratios of multilayer follicle:total follicle (ML:TF), and follicle growth rates were compared between groups. Follicle densities were significantly higher in the extracellular matrix treatment group compared with the polylysine group (P < 0.01). Also, compared with polylysine, both collagen and laminin significantly increased indices of follicle growth initiation (PY:PD ratio: P < 0.001, odds ratio of 3.3; PY:TF ratio: P < 0.001, odds ratio of 2.5), and these were not altered by activin treatment. In the absence of activin-A, exposure to neither collagen nor laminin had an effect on multilayer follicle development. When activin-A was added, collagen and laminin had opposing effects on multilayer follicle development. Activin-A stimulated multilayer follicle development in the presence of laminin (ML:TF ratio: P = 0.01, odds ratio of 10.8), whereas it suppressed follicle growth in collagen (P = 0.01). Activin-A did not affect the ML:TF ratio in the polylysine-treated groups. These results strongly suggest that extracellular matrix components and activin-A interact with each other, and that they regulate follicle growth initiation and multilayer follicle development.

Section: Discussionmentioning

confidence: 94%

Interaction of Extracellular Matrix and Activin-A in the Initiation of Follicle Growth in the Mouse Ovary1

Oktay

Karlikaya

Akman

et al. 2000

“…Previous studies have demonstrated the presence of fibronectin in the follicle layers of ovarian follicles in mammals [34][35][36][37][38], as well as in teleost fish [39]. Fibronectin is presumed to stabilize and maintain the ECM environment and normal cell adhesion by interacting with collagen type IV and the cell surface receptor protein integrin [37,38].…”

Section: Discussionmentioning

confidence: 99%

Apparent Involvement of Plasmin in Early-Stage Follicle Rupture During Ovulation in Medaka1

Ogiwara¹,

Minagawa²,

Takano³

et al. 2012

Until recently, the role of the proteolytic system involving serine proteases in follicle rupture during ovulation in mammalian species has been a subject of controversy. We undertook the present study to examine whether proteases play a role in follicle rupture using the teleost medaka (Oryzias latipes) model. Various serine protease inhibitors, including a specific plasmin inhibitor, drastically reduced the rate of ovulation, as assessed by an in vitro ovulation assay, which was established for the fish. Biochemical, molecular biological, and immunological analyses demonstrated that plasminogen/plasmin was present in large follicles destined to ovulate. The active protease, plasmin, was detected in follicles approximately 3-7 h before the expected time of ovulation. Specific antibodies against the medaka plasmin light chain suppressed the ovulation rate of the follicles when antibodies were added to the medium during the period in which active plasmin was generated. This finding was an indication that a plasmin-like protease similar if not identical to plasmin plays a role in follicle rupture during ovulation in the medaka. Our data also indicate that this serine protease participates in the rupture for only a few hours prior to the activation of matrix metalloproteinase (Mmp)-mediated hydrolysis at ovulation. Based on our previous and current data, we propose a follicle rupture model involving two different proteolytic enzyme systems, serine protease and Mmp, in medaka ovulation. The current study is the first to provide evidence of the indispensable role of plasmin or a plasmin-like protease in the ovulation of a nonmammalian vertebrate species.

“…All procedures were performed at room temperature. The cells were first fixed (5 min) with 3.7% paraformaldehyde in PBS and then permeabilized (20 min) with 0.1% PBS-Nonidet P-40 [25,26]. The cells were rinsed with PBS and then incubated (45 min) with a specific antiserum to laminin or collagen IV (rabbit anti-mouse; Collaborative Research) or to fibronectin (goat anti-human; Terochem Laboratories, Toronto, ON).…”

Section: Immunolocalization Of Extracellular Matrix Glycoproteinsmentioning

confidence: 99%

Extracellular Matrix Composition and Resilience: Two Parameters that Influence the in Vitro Migration and Morphology of Rat Inner Cell Mass-Derived Cells1

Carnegie

Cabaca

1993

Parietal endodermal (PE) migration along rat trophectodermal (TE) cells coincides with the deposition of Reichert's membrane between these two cell layers. In this study, we compared the influences of fibronectin and laminin, two components of Reichert's membrane, on the migration and replication of PE-like cells from cultured rat inner cell masses (ICMs). We also explored the role of substrate nondeformability by comparing cell translocation on gels versus coatings of Matrigel (a tumor cell-derived basement membrane preparation) or of collagen. ICMs, isolated by immunosurgery from Day 5 blastocysts, were cultured on coatings of collagen IV, laminin, fibronectin, collagen I, or Matrigel, or on gels of the latter two substrates. Minimal laminin or fibronectin coating concentrations of 2.5 micrograms/ml were required for ICM attachment and cell migration. Migration was similar during the first 48 h of culture on fibronectin and on laminin; however, by 72 h, the extent of cell translocation on fibronectin was greater (1.5- to 2-fold) than that measured on laminin. Fibronectin-cultured ICM-derived cell clusters also contained 1.5- to 2-fold more cells than those on laminin. Migration did not occur on undiluted gels of Matrigel but was supported by diluted (1:10 and 1:20) Matrigel coatings. Similarly, cell migration on coatings of collagen IV reached almost 3-fold that measured on collagen I gels. Most of the cells migrating on fibronectin or collagen (I or IV) were flattened and elongated. In contrast, a high proportion of the cells migrating on laminin or Matrigel coatings were tall and rounded, with thin cytoplasmic extensions. Fibronectin- and collagen IV-cultured cells stained strongly for both collagen IV and laminin, but contained no fibronectin. In contrast, laminin-cultured cells contained fibronectin but were less immunoreactive for laminin and collagen IV. These findings indicate that substrate composition and resilience influence the in vitro migration and morphology of ICM-derived PE-like cells. A role for the TE cells in anchoring Reichert's membrane during development of the PE cell layer within the blastocyst is postulated. Furthermore, the sensitivity of cell morphology and differentiation to individual basement membrane components provides a potential key mechanism whereby an emerging basement membrane can regulate cell migration and differentiation, two fundamental processes that occur throughout embryonic development.