Follicular maturational competence and ovulatory competence in teleost fish refer to the ability of the ovarian follicle to undergo final oocyte maturation and ovulation, respectively, in response to gonadotropin stimulation and other external cues. Some gene products related to competence acquisition are likely synthesized during vitellogenic growth, as these follicles gain in vivo responsiven...

BACKGROUND Given the controversies regarding the effectiveness of gonadotropin-releasing hormone (GnRH) antagonists in prevention of ovarian hyper stimulation syndrome stimulation, this study was designed to compare GnRH agonist protocol with GnRH antagonist protocol in patients who were candidate for assisted reproductive techniques (ARTs). MATERIALS AND METHODS This investigation was perfor...

The regulation of LH and FSH subunit gene expression is under the control of GnRH. Physiological changes in the frequency of pulsatile GnRH release from the hypothalamus result in differential stimulation of alpha-, LHbeta-, and FSHbeta-gene expression. Previous studies indicate that the GnRH receptor couples to G proteins of the G(q/11) family, with phosphoinositide turnover and its resultant ...

BACKGROUND Over the last several decades, as a result of an evolution in manufacturing processes, a marked development has been made in the field of gonadotropins for ovarian stimulation. Initially, therapeutic gonadotropins were produced from a simple process of urine extraction and purification; now they are produced via a complex system involving recombinant technology, which yields gonadotr...

The management of poor responders in IVF cycles is extremely controversial due to their inadequate response to controlled ovarian hyperstimulation.. A low ovarian response may be idiopathic or may be associated with many different factors including age, diminished ovarian reserve, endometriosis and prior ovarian surgery, and a reported incidence 9-24% of IVF patients. Several strategies have be...

BACKGROUND Clomiphene citrate (CC) an agonist and antagonist of estrogen, is the first line treatment in ovarian stimulation. Anti-estrogenic effect of CC in endometrial thickness and cervical mucus has negative effect on pregnancy rate. Letrozole is an Aromatase Inhibitor has been seen that has acceptable pregnancy rate compared to CC. OBJECTIVE The aim of this study was to compare the effic...

In mammals, gonadal function is controlled by the activity of hypothalamic gonadotropin-releasing hormone neurons, which control the secretion of adenohypophyseal and gonadal hormones. However, there are a number of unanswered questions in relation to gonadal function. It is currently unknown how erotogenic stimulation of the genitals influences the subpopulation of hypothalamic medial preoptic...

The central nervous system, especially the hypothalamus, exerts an influence on the gonadotropin secretion from the anterior pituitary, resulting in the stimulation of gonads. The sex steroids, in turn, react back on the central nervous system in order to adjust the anterior pituitary function for reproductive cycles (Harris, 1955a). As reported in the previous paper (Kobayashi et al., 1963), t...