The extrapituitary effects of GnRH antagonists and their potential clinical implications: a narrated review.

Potential roles of gonadotropin-releasing hormone (GnRH) antagonists on GnRH/GnRH receptor systems and their effects on the extrapituitary tissues are largely elusive. In this narrated review, we summarized the systemic effects of GnRH antagonists on ovary, endometrium, embryo implantation, placental development, fetal teratogenicity, reproductive tissue cancer cells, and heart while briefly reviewing the GnRH and GnRH receptor system. GnRH antagonists may have direct effects on ovarian granulosa cells.

Sperm DNA damage: how relevant is it clinically?

Purpose Of Review: The true impact of the current sperm DNA fragmentation testing needs further scrutiny to assess whether clinically meaningful information is conveyed.

Recent Findings: Various studies have suggested different or no threshold values with assorted tests for the percentage of DNA fragmentation in the ejaculated sperm above which natural conception, fertilization or embryo development and/or clinical pregnancy rates are compromised. Current DNA fragmentation assessment methods provide very little specific information on the nature and severity of the DNA damage detected.

The nucleolar channel system reliably marks the midluteal endometrium regardless of fertility status: a fresh look at an old organelle.

Objective: To determine whether nucleolar channel systems (NCSs) in the midluteal endometrium are associated with overall fertility status and/or with unexplained infertility.

Design: Retrospective and prospective clinical studies.

Setting: Repository of stored specimens from prior multicenter study and private infertility center.

17α-Hydroxylase (CYP17) expression and subsequent androstenedione production in the human ovary.

Traditionally, in women, only the theca cells in the ovary and the zona reticularis layer of the adrenal cortex are believed to synthesize androgens. Interestingly, their neighboring cell layers, the granulosa cells and the zona glomerulosa cells, respectively, do not produce androgens. Recent literature has highlighted the role of the activator protein (AP-1) transcription factor, c-Fos, in the dynamics of this structural and functional relationship.

Molecular mechanism for repression of 17alpha-hydroxylase expression and androstenedione production in granulosa cells.

Context: According to the traditional two-cell two-gonadotropin model of follicular steroidogenesis, androgen production arises exclusively from theca cells. The granulosa cells, in turn, utilize androstenedione and testosterone, which are aromatized into estrone and estradiol, respectively. Differential expression of the activator protein-1 (AP-1) transcription factor, c-fos, has been postulated to result in distinct patterns of steroidogenesis in the theca and granulosa cell compartments.

The mechanism for protein kinase C inhibition of androgen production and 17alpha-hydroxylase expression in a theca cell tumor model.

Introduction: In polycystic ovary syndrome (PCOS), there is increased formation of androgens by thecal cells. Moreover, PCOS ovaries have been shown to have decreased levels of c-fos transcription factor. We hypothesize that c-fos expression inhibits 17alpha-hydroxylase 17,20 lyase (CYP17) activity in the human ovary, and its decreased expression seen in PCOS may lead to elevated CYP17 transcription, resulting in increased androgen production.

Pituitary tumors: diagnosis, management, and implications for reproduction.

Pituitary tumors are the most common intracranial neoplasms. They are commonly encountered by the gynecologist during an evaluation for galactorrhea, menstrual disturbances, or infertility. Although the majority of these tumors are benign, their impact on the endocrine and nervous system can be striking.

The human fetal adrenal gland, corticotropin-releasing hormone, and parturition.

Labor initiation is a complex process that remains to be fully elucidated. An area of active research involves the study of the different mechanisms that may lead to successful signaling for parturition. This review focuses on the fetal-derived signals that lead to the initiation of labor.

Activity-dependent change in morphology of the glial tubular lattice of the crayfish medial giant nerve fiber.

An evaluation of electron micrographs of stimulated nerve fibers used to investigate the effect of action potential generation on the structure-function relationship between axons and its associated glial cells revealed that what was at first thought to be stimulation-induced damage to the glia was, in fact, limited to volume expansion and disaggregation of the glial tubular lattice. All other structures appeared well preserved and otherwise normal. Using a 4-point subjective scale for evaluation by two investigators, 50-Hz stimulation for 2 min was observed to cause a volume expansion and disaggregation of the tubular lattice.