background: this study was aimed to assess the effects of angiotensin ii (ang ii) supplementation to the in vitro maturation (ivm) and in vitro culture (ivc) media of vitrified-warmed ovine oocytes on their developmental competence and expression of na+/k+/atpase in resulting embryos. methods: the slaughterhouse-derived immature oocytes (n=1069) were randomly distributed into four experimental ...

The present studies have been undertaken to investigate the interactions that occur between the nucleus and cytoplasm of ovine oocytes at various stages during meiotic maturation. We report that the nucleus of ovine fully grown dictyate stage oocytes can be efficiently removed by a microsurgical enucleation procedure. It is demonstrated that between the initiation of maturation and germinal ves...

Background: Oocyte in vitro maturation success rate is still low in compareision to oocyte in vivo maturation. Thus prediction and improvement of oocyte competency are two critical issues in assisted reproductive technology. New insights into oocyte-cumulus cell regulatory loop may assist our optimization of in vitro maturation technique. Maturation and developmental competency of cumulus oocyt...

Mitochondrial DNA (mtDNA) is normally only inherited through the oocyte. However, nuclear transfer (NT), the fusion of a donor cell with an enucleated oocyte, can transmit both donor cell and recipient oocyte mtDNA. mtDNA replication is under the control of nuclear-encoded replication factors, such as polymerase gamma (POLG) and mitochondrial transcription factor A (TFAM). These are first expre...

Follicle and oocyte growth is under the control of systemic gonadotropins and various local intraovarian factors. The present study was undertaken to examine the efficacy of peptide(s) isolated from ovine follicular fluid on preantral and antral follicles, oocytes, cumulus and granulosa cells, and oviductal epithelial cell growth in vitro in a heterologous species (Bubalus bubalis). Follicular ...

Background: Heat shock may affect different aspects of oocyte maturation and its subsequent development to the blastocyst stage. A series of in vitro experiments was performed to determine whether physiologically heat shock (41°C) disrupts the progression of the ovine oocytes through meiosis, activation and blastocyst formation. Materials and Methods: The cumulus-oocyte complexes (COCs) were as...

the aim of the present study was to investigate the effect of follicle stimulating hormone (fsh) on survival, activation and growth of ovine primordial follicles using histological studies. pieces of ovine ovarian cortex were obtained and cultured for 6 days in minimum essential medium supplemented with or without fsh (50 ng/ml). these fragments were then process to be used for histology compar...

Physical removal of mammalian cumulus-oocyte complexes (COCs) from ovarian follicles results in spontaneous resumption of meiosis, largely because of a decrease in cAMP concentrations, causing asynchrony between cytoplasmic and nuclear maturation and decreased oocyte developmental competence. The aim of this study was to modulate cAMP concentrations within ovine COCs to delay spontaneous nuclea...

Activins have been implicated as important regulating factors for many reproductive processes. The aim of this study was to determine the effect of activin A on the development of ovine preantral follicles in vitro. Mechanically isolated preantral follicles (161 +/- 2 microm) were cultured for 6 days in the presence of human recombinant activin A (0, 10 and 100 ng/ml). Half of the medium was re...