36,594 research outputs found
Morphological classification of bovine ovarian follicles
No full textCopyright © 2010 Society for Reproduction and FertilityFollicle classification is an important aid to the understanding of follicular development and atresia. Some bovine primordial follicles have the classical primordial shape, but ellipsoidal shaped follicles with some cuboidal granulosa cells at the poles are far more common. Preantral follicles have one of two basal lamina phenotypes, either a single aligned layer or one with additional layers. In antral follicles 5 mm, only aligned/rounded phenotypes are present. Dominant and subordinate follicles can be identified by ultrasound and/or histological examination of pairs of ovaries. Atretic follicles 5 mm, only antral atresia is observed. The concentrations of follicular fluid steroid hormones can be used to classify atresia and distinguish some of the different types of atresia; however, this method is unlikely to identify follicles early in atresia, and hence misclassify them as healthy. Other biochemical and histological methods can be used, but since cell death is a part of normal homoeostatis, deciding when a follicle has entered atresia remains somewhat subjective.R. J. Rodgers and H. F. Irving-Rodger
Extracellular matrix in ovarian follicular development and disease
No full textThe original publication is available at www.springerlink.comThe ovarian follicle contains several different cell types and separate compartments and undergoes substantial development during its growth and maturation. Extracellular matrix (ECM) could be expected to play a major role in these processes. Most research on ECM in follicles has focused on the follicular basal lamina and its changing composition during folliculogenesis and on the specialised matrix formed at ovulation by the cumulus cells surrounding the oocyte and the zona pellucida. We review these aspects. Few naturally occurring gene mutations have identified unique roles for ECM molecules in follicular function. Presumably, any mutations leading to reduced fertility are eliminated quickly by natural selection and, when mutations are not eliminated, considerable redundancy occurs to ensure successful reproduction. In mice, in which the genome can be easily manipulated, the modification of matrix components associated with cumulus and oocytes has often resulted in partial infertility, suggesting redundancy. We provide an update of basal lamina components focusing on newer discoveries. In addition, we review matrix associated with the occyte and cumulus cells (excluding the zona pellucida) and other components of ECM. Where possible, we examine evidence for the role of the ECM in follicular development and diseases.Helen F. Irving-Rodgers and Raymond J. Rodger
Formation of the ovarian follicular antrum and follicular fluid
No full textThe formation of the follicular antrum and follicular fluid has received scant attention from researchers, yet both are important processes in follicular development. The central hypothesis on follicular fluid formation suggests that production by granulosa cells of hyaluronan and the chondroitin sulphate proteoglycan versican generates an osmotic gradient. This gradient draws in fluid derived from the thecal vasculature. Inter-alpha-trypsin inhibitor is also present in follicular fluid at least in species with large follicles, and inter-alpha-trypsin inhibitor and versican could additionally bind or cross-link with hyaluronan, resulting in the retention of these molecules within the follicular antrum. Barriers to the movement of fluid across the membrana granulosa are apparently minimal, as even relatively large serum proteins are present in follicular fluid. Despite the relative permeability of the follicular wall, aquaporins are present in granulosa cells and could be actively involved in the transport of water into the follicle. The formation of an antrum also requires movement of granulosa cells relative to each other to allow the fluid to accumulate. This presumably involves remodeling of cell-cell junctions and in species with small follicles may involve death of centrally located granulose cells. Remodeling of the stroma and thecal layers also accompanies growth and expansion of the antrum and presumably involves similar processes that accompany growth of other glands.Raymond J. Rodgers and Helen F. Irving-Rodger
Extracellular matrix of the developing ovarian follicle
No full textThere are many different types of extracellular matrices in the different follicle compartments. These have different roles in follicle development and atresia, and they change in composition during these processes. This review focuses on basal lamina matrix in particular, and considers follicular fluid, the newly identified focimatrix, and thecal matrices. When follicles commence growing, the follicular basal lamina changes in its composition from containing all six alpha chains of type IV collagen to only alpha1 and alpha2. Perlecan and nidogen-1 and -2 subsequently become components of the follicular basal lamina, and there is an increase in the amount of laminin chains alpha1, beta2, and gamma1, in the bovine at least. Late in follicular development and on atresia some follicles contain laminin alpha2. On atresia the follicular basal lamina is not degraded, as occurs in ovulation, but can be breached by cells from the thecal layer when it is not aligned by granulosa cells. A novel type of basal lamina-like matrix, called focimatrix (abbreviated from focal intraepithelial matrix), develops between the cells of the membrana granulosa as aggregates of basal lamina material. It does not envelop cells and so cannot perform functions of basal lamina as currently understood. It is hypothesized that focimatrix assists or initiates depolarization of the membrana granulosa necessary for the transformation into luteal cells. The largest osmotically active molecules in follicular fluid are hyaluronan and chondroitin sulfate proteoglycans, including versican and inter-alpha trypsin inhibitor. It has been suggested that these might be responsible for the formation of follicular fluid by creating an osmotic gradient across the follicular wall. The formation, development, and then either ovulation or regression of follicles requires considerable tissue remodeling, cellular replication, and specialization. The expectation of researchers is that extracellular matrix will be intimately involved in many of these processes. Much research has focused in identifying the components of extracellular matrix and associated developmental changes. We review the components of extracellular matrix associated with follicular development, including the basal lamina, focimatrix, follicular fluid, and matrix of the thecal layers.Helen F. Irving-Rodgers, Raymond J. Rodger
Pancreatic islet basement membrane loss and remodeling after mouse islet isolation and transplantation: impact for allograft rejection
No full textThe isolation of islets by collagenase digestion can cause damage and impact the efficiency of islet engraftment and function. In this study, we assessed the basement membranes (BMs) of mouse pancreatic islets as a molecular biomarker for islet integrity, damage after isolation, and islet repair in vitro as well as in the absence or presence of an immune response after transplantation. Immunofluorescence staining of BM matrix proteins and the endothelial cell marker platelet endothelial cell adhesion molecule-1 (PECAM-1) was performed on pancreatic islets in situ, isolated islets, islets cultured for 4 days, and islet grafts at 3-10 days posttransplantation. Flow cytometry was used to investigate the expression of BM matrix proteins in isolated islet β-cells. The islet BM, consisting of collagen type IV and components of Engelbreth-Holm-Swarm (EHS) tumor laminin 111, laminin α2, nidogen-2, and perlecan in pancreatic islets in situ, was completely lost during islet isolation. It was not reestablished during culture for 4 days. Peri- and intraislet BM restoration was identified after islet isotransplantation and coincided with the migration pattern of PECAM-1+vascular endothelial cells (VECs). After islet allotransplantation, the restoration of VEC-derived peri-islet BMs was initiated but did not lead to the formation of the intraislet vasculature. Instead, an abnormally enlarged peri-islet vasculature developed, coinciding with islet allograft rejection. The islet BM is a sensitive biomarker of islet damage resulting from enzymatic isolation and of islet repair after transplantation. After transplantation, remodeling of both peri- and intraislet BMs restores β-cell-matrix attachment, a recognized requirement for β-cell survival, for isografts but not for allografts. Preventing isolation-induced islet BM damage would be expected to preserve the intrinsic barrier function of islet BMs, thereby influencing both the effector mechanisms required for allograft rejection and the antirejection strategies needed for allograft survival.H. F. Irving-Rodgers, F. J. Choong, K. Hummitzsch, C. R. Parish, R. J. Rodgers and C. J. Simeonovi
Studies of granulosa cell maturation in dominant and subordinate bovine follicles: novel extracellular matrix focimatrix is co-ordinately regulated with cholesterol side-chain cleavage CYP11A1
No full textDuring growth of antral ovarian follicles granulosa cells first become associated with a novel type of extracellular matrix, focimatrix, and at larger sizes follicles become either subordinate or dominant. To examine this, bovine subordinate (9.0+/-S.E.M. 0.4 mm; n=16), partially dominant (12.0+/-0.6 mm; n=18) and fully dominant (15.0+/-0.4 mm; n=14) follicles were examined by real time RT-PCR analyses of granulosa cells and by immunohistochemistry of focimatrix. Changes in the expression of FSH receptor, LH receptor, cholesterol side-chain cleavage (CYP11A1), 3beta-hydroxysteroid dehydrogenase, aromatase (CYP19A1) and inhibin-alpha and beta-B were observed as expected for follicle sizes examined. After adjusting for size differences, only CYP11A1 was significantly different between the groups, and elevated in dominant follicles. Also after adjusting for differences in size there were no significant differences in expression of focimatrix components collagen type IV alpha-1 (COL4A1), laminin beta-2, nidogen 1 (NID1), and perlecan (HSPG2) or the volume density of NID1 and -2 and HSPG2. The volume density of focimatrix components in laminin 111 was significantly elevated in dominant follicles. Adjusting for analysis of more than one follicle per animal and for multiple correlations, CYP11A1 mRNA levels were highly correlated with the focimatrix genes COL4A1, NID1 and -2 and HSPG2. Thus, focimatrix may potentially regulate CYP11A1 expression, and the regulation of both could be important in follicular dominance.H. F. Irving-Rodgers, M. L. Harland, T. R. Sullivan and R. J. Rodger
Dietary manipulation of Bos indicus x heifers during gestation affects the reproductive development of their heifer calves
No full textThe effect of nutrition during the first and second trimesters of pregnancy in composite beef heifers on reproductive parameters of their female calves was determined in the present study. At artificial insemination, heifers were assigned to one of four treatment groups (i.e. HH, HL, LowH and LL) depending on the level of crude protein intake (H = high; L = low) for first and second trimesters of pregnancy. Gonadotrophin concentrations and ovarian parameters were measured in their female calves at 5 and 23 months of age. Crude protein intake was positively associated with dam plasma urea (P < 0.001). The density of healthy follicles in heifers at the time of death was negatively correlated with dam plasma urea at Day 179 (P = 0.009). Heifers from LowH dams had a smaller-sized prepubertal largest ovarian follicle (P = 0.03) and lower densities of primordial and primary follicles (P = 0.02) and healthy antral follicles (P = 0.009) when they were killed. There was a positive correlation between plasma FSH concentrations at 5 and 23 months of age (P = 0.02), as well as between the sizes of the largest ovarian follicles at 6 and 23 months of age (P = 0.01). In conclusion, the reproductive development of heifers may be affected by prenatal nutrition during early and mid-gestation.T.M. Sullivan, G.C. Micke, R.M. Greer, H.F. Irving-Rodgers, R.J. Rodgers and V.E.A. Perr
Molecular composition of the peri-islet basement membrane in NOD mice: a barrier against destructive insulitis
No full textAims/hypothesisThis study examined whether the capsule which encases islets of Langerhans in the NOD mouse pancreas represents a specialised extracellular matrix (ECM) or basement membrane that protects islets from autoimmune attack.MethodsImmunofluorescence microscopy using a panel of antibodies to collagens type IV, laminins, nidogens and perlecan was performed to localise matrix components in NOD mouse pancreas before diabetes onset, at onset of diabetes and after clinical diabetes was established (2-8.5 weeks post-onset).ResultsPerlecan, a heparan sulphate proteoglycan that is characteristic of basement membranes and has not previously been investigated in islets, was localised in the peri-islet capsule and surrounding intra-islet capillaries. Other components present in the peri-islet capsule included laminin chains alpha2, beta1 and gamma1, collagen type IV alpha1 and alpha2, and nidogen 1 and 2. Collagen type IV alpha3-alpha6 were not detected. These findings confirm that the peri-islet capsule represents a specialised ECM or conventional basement membrane. The islet basement membrane was destroyed in islets where intra-islet infiltration of leucocytes marked the progression from non-destructive to destructive insulitis. No changes in basement membrane composition were observed before leucocyte infiltration.Conclusions/interpretationThese findings suggest that the islet basement membrane functions as a physical barrier to leucocyte migration into islets and that degradation of the islet basement membrane marks the onset of destructive autoimmune insulitis and diabetes development in NOD mice. The components of the islet basement membrane that we identified predict that specialised degradative enzymes are likely to function in autoimmune islet damage.H. F. Irving-Rodgers, A. F. Ziolkowski, C. R. Parish, Y. Sado, Y. Ninomiya, C. J. Simeonovic, R. J. Rodger
The marriage record of Rodgers, James F. and Jernigan, Olive H
No full textMarriage license for Olive H. Jernigan and James F. Rodgers
Expression and distribution of cytokeratin 8/18 intermediate filaments in bovine antral follicles and corpus luteum: An intrinsic mechanism of resistance to apoptosis?
No full textApoptosis is a mechanism of cell elimination during follicular atresia and luteal regression. Recent evidence suggests sensitivity to apoptosis in some cell types is partly dependent upon cytokeratin-containing intermediate filaments. Specifically, cytokeratin 8/18 (CK8/18) filaments are thought to impart resistance to apoptosis. Here, cytokeratin filament expression within bovine ovarian follicles and corpora lutea (CL) was characterized and the potential relationship between cell-specific CK8/18 expression and apoptosis explored. Immunoprecipitation and western blot analysis confirmed CK8 associates with CK18 to form CK8/18 heterodimeric filaments within bovine ovarian cells. Immunostaining revealed populations of CK18-positive (CK18+) cells in healthy growing follicles that increased in postovulatory follicles. Atretic follicles at all stages of atresia also contained some CK18+ cells. However, no CK18+ cells were detected in primordial or primary follicles. In CL, developing CL contained a higher proportion of CK18+ cells (similar to 35%, range 30-70%) than mature CL (similar to 16%) and regressing CL (similar to 5%; P<0.05, n = 3-5 CL/stage), suggesting CK8/18 filament expression diminishes over time, as luteal cells become more susceptible to apoptosis. Dual-fluorescence labeling for CK18 and a cell death marker (TUNEL labeling) confirmed this view, demonstrating less death of CK18+ than CK18-luteal cells throughout the estrous cycle (P<0.05). The results indicate differential expression of CK8/18 filaments occurs in cells of bovine ovarian follicles and CL throughout the estrous cycle. The prevalence and cell-specific pattern of cytokeratin expression in these structures is consistent with the concept these filaments might impart resistance to apoptosis in ovarian cells as is seen in other cell types.David H. Townson, Amanda N. Putnam, Brian T. Sullivan, Lankai Guo, Helen F. Irving-Rodger
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