How the Oocyte Nucleolus Is Turned into a Karyosphere: The Role of Heterochromatin and Structural Proteins.

Oocyte meiotic maturation includes large-scale chromatin remodeling as well as cytoskeleton and nuclear envelope rearrangements. This review addresses the dynamics of key cytoskeletal proteins (tubulin, actin, vimentin, and cytokeratins) and nuclear envelope proteins (lamin A/C, lamin B, and the nucleoporin Nup160) in parallel with chromatin reorganization in maturing mouse oocytes. A major feature of this reorganization is the concentration of heterochromatin into a spherical perinucleolar rim called surrounded nucleolus or karyosphere.

Lupus progression deteriorates oogenesis quality in MRL/lpr mice.

Systemic lupus erythematosus (SLE) is an autoimmune disease characterized by the activation of the immune response against self antigens. Numerous reproductive complications, including reduced birth rate and complications for the mother and the fetus during pregnancy, have been observed in women with SLE. In the present study, we aimed to investigate the effect of SLE development on oocyte meiosis in lupus-prone mice.

Osteoarthritis Affects Mammalian Oogenesis: Effects of Collagenase-Induced Osteoarthritis on Oocyte Cytoskeleton in a Mouse Model.

Known as a degenerative joint disorder of advanced age affecting predominantly females, osteoarthritis can develop in younger and actively working people because of activities involving loading and injuries of joints. Collagenase-induced osteoarthritis (CIOA) in a mouse model allowed us to investigate for the first time its effects on key cytoskeletal structures (meiotic spindles and actin distribution) of ovulated mouse oocytes. Their meiotic spindles, actin caps, and chromatin were analyzed by immunofluorescence.

Defective oogenesis in mice with pristane-induced model of systemic lupus.

Systemic lupus erythematosus (SLE) is a chronic systemic autoimmune disease characterized by generation of autoantibodies and severe damage of various organs. The hormonal changes associated with pregnancy and especially estrogen might lead to damage of reproductive function and ovarian quality. We employed a pristane-induced lupus model of Balb/c mice which resembles human lupus in an attempt to follow oogenesis disruption during the disease progression.

Follicle stimulating hormone and estradiol alter immune response in osteoarthritic mice in an opposite manner.

Although a number of studies have shown that the occurrence and progression of osteoarthritis (OA) is related to endocrine system dysfunction, there is limited evidence about what roles sex hormones play. The aim of the present study was to examine the capacity of 17β-estradiol (ED) and follicle stimulating hormone (FSH) to alter the differentiation of bone marrow (BM) cells in arthritic mice. The experiments were conducted in collagenase-induced osteoarthritis in mice.

Prostaglandin F2α Causes Fast Degenerative Changes in Ovulated Mouse Oocytes.

The effects of prostaglandin F2α on the cytoskeleton and membrane organelles of oocytes was investigated by culturing ovulated mouse oocytes in its presence (50 or 100 ng/ml) for 3 h. Tubulin, fibrillar actin, membranes and chromatin were visualized by specific antibodies, phalloidin, lipophilic dye DiOC6 and Hoechst 33342, respectively. Control oocytes were characterized by a meiotic spindle with chromosomes aligned at its equator, and a cortical layer of microfilaments with an actin cap.

Influence of estradiol treatment on bone marrow cell differentiation in collagenase-induced arthritis.

Objective And Design: Estrogen is one of the important regulators of the balance between bone formation and bone resorption that can modulate the levels and activity of certain growth factors and cytokines. In this study, we investigated the effect of 17β-estradiol (ED) on bone marrow (BM) cell differentiation in vivo and ex vivo in a mouse model of collagenase-induced osteoarthritis (CIOA).

Subject: ICR (CD-2) female mice were used in present experiments (total number = 75) and bone marrow cells were used for in vitro studies.

Dynamics of Lamins B and A/C and Nucleoporin Nup160 during Meiotic Maturation in Mouse Oocytes.

This study was aimed at elucidating the fate of three important nuclear envelope components - lamins B and A/C and nucleoporin Nup160, during meiotic maturation of mouse oocytes. These proteins were localized by epifluorescence and confocal microscopy using specific antibodies in oocytes at different stages from prophase I (germinal vesicle) to metaphase II. In immature germinal vesicle oocytes, all three proteins were detected at the nuclear periphery.

[Investigation of cytokeratin and vimentin intermediate filaments in polycystic ovaries (PCOS) -- presence and specific structure of Balbiani body in primordial follicles].

Despite of the importance of cytoskeletal proteins for ovarian function and pathology, very few studies have addressed the presence and distribution of these proteins in polycystic ovaries. We investigated sections of human polycystic ovarian tissue for vimentin and a set of cytokeratins by epifluorescence. The studied proteins showed strong colocalization.

[Laparoscopic ovarian drilling and biopsy in women with polycystic ovaries (PCOS) and infertility].

Objectives: To evaluate ovarian reserve according to results of biopsy of ovaries during laparoscopy. To investigate connections between hystologic results, drilling of ovaries and pregnancies.

Methods: We investigate prospectively 74 patients with polycystic ovaries (PCOS) and infertility.

[Role of oocyte cytoplasmic factors in human IVF failure].

Premature chromosome condensation (PCC) of the sperm chromatin and abnormal dispersion of oocyte chromosomes are independent indirect indicators for cytoplasmic immaturity and cytoskeletal anomalies in the oocyte affecting the normal zygote and embryo formation in human IVF-ET practice. In a group of 66 human unfertilized oocytes, two types of cytoplasmic factors were registered: PCC in 49 (74.24%) and cytoskeletal anomalies in 17 oocytes (25.

Analysis of human unfertilized oocytes and pronuclear zygotes--correlation between chromosome/chromatin status and patient-related factors.

Objective: The objective was to evaluate the relationship between ploidy and chromatin status of human unfertilized oocytes/zygotes and infertility history, female age, and stimulation regimens.

Study Design: Two hundred and eighty-nine unfertilized oocytes and 63 zygotes were subjected to cytogenetic analysis: karyotyping for oocytes and fluorescent in situ hybridization (FISH) analysis for zygotes. Ploidy and chromosome/chromatin status were analyzed according to stimulation regimen, female age, and infertility history.

Meiotic abnormalities in in vitro-matured marmoset monkey (Callithrix jacchus) oocytes: development of a non-human primate model to investigate causal factors.

Background: Meiotic abnormalities are thought to be a major causal factor of low embryo development rates, for embryos developed from in vitro-matured oocytes. A new non-human primate model, in the common marmoset, is being developed to facilitate investigation of the mechanisms involved.

Methods: Oocytes were dissected from antral follicles from three size classes.

Chromosomal disorders and nuclear and cell destruction in cleaving human embryos.

Three types of defects of preimplantation embryogenesis contribute to the developmental arrest of cleaving human embryos: blastomere fragmentation, abnormal nuclear status and chromosomal disorders. Data concerning the relation and succession of these abnormalities during first mitotic cycles of the human zygote are controversial and mainly empirical at present. In this study we have performed simultaneous evaluation of blastomere fragmentation, nuclear apoptotic changes and the ploidy of four chromosomes (1, 5, 19 and X or 18, 21, X and Y) in 193 human embryos.

Ploidity and chromatin status of human oocytes after failed in vitro fertilization.

Objective: To investigate the chromatin status of oocytes and their ploidity in order to consider possible genetic reasons for their unsuccessful fertilization in vitro.

Study Design: Eighty-six unfertilized in vitro human oocytes were scored in six groups according to their chromatin status. Analysis was performed by cytogenetics and by fluorescent in situ hybridization (FISH).

Possible cytoskeletal structures of rainbow trout sperm revealed by electron microscopic observation after detergent extraction.

Despite the considerable research interest in fish sperm ultrastructure, little is known about the functions of different sperm cell components. Our electron microscopic study was aimed at identifying possible tissue-specific cytoskeletal structures in spermatozoa of rainbow trout Oncorhynchus mykiss (Teleostei, Salmoniformes, Salmonidae; formerly Salmo gairdneri). Based on the known resistance of the cytoskeleton to nonionic detergents, we compared the ultrastructure of unextracted and Triton-extracted sperm cells.

Supernumerary human preembryos provide potential for preimplantation genetic diagnosis.

Preimplantation genetic diagnosis is an alternative to the classical prenatal diagnosis for couples undergoing in vitro fertilization. It allows very early embryo selection--before the intrauterine embryo transfer. Prior to clinical application of preimplantation diagnosis in the Infertility Treatment Centre "Technobioassistance", Sofia Medical Faculty, we have developed preimplantation diagnosis models of human spermatozoa and untransferred 2-8-cell human embryos obtained in vitro.