Reproduction Abstracts

Whether the adult mammalian ovary contains oogonial stem cells (OSCs) is controversial. They have been isolated by fluorescence-activated cell sorting (FACS) using the germline marker DEAD box polypeptide 4 (DDX4), previously assumed to be cytoplasmic, not surface-bound. Furthermore their stem cell and germ cell characteristics remain disputed. We applied a validated protocol to isolate mouse putative OSCs from whole ovarian cell suspensions, then assessed their in vitro</...

Introduction: It has recently been demonstrated that mouse oocytes respond to DNA damage by arresting in Meiosis I. This arrest has been shown to require the activity of the Spindle Assembly Checkpoint (SAC) and the DNA Damage Response (DDR). Given oocytes lack the equivalent of a G2/M checkpoint for DNA damage, the SAC response may be critical to defend against formation of DNA damaged embryos. It is currently unknown whether the DDR SAC pathway is sensitive to physiological ...

Chromosomes must be properly segregated during meiosis to transmit the correct set of the parental genome into gametes. Incorrect chromosome segregation produces aneuploid gametes, fertilization of which results in pregnancy loss and congenital diseases such as Down syndrome. However, it is known that the frequency incorrect chromosome segregation is extremely high at meiosis I in oocytes (20–40% in humans), compared to other cell divisions. Moreover, the frequency of the...

Female meiosis involves a highly asymmetrical division to form a large secondary oocyte and a small polar body. Polo-like kinase I (Plk1) is a serine/threonine kinase which is highly conserved from yeast to human and is a potent regulator of mitosis including cytokinesis. Plk1 is known to regulate myosin via the activation of RhoA which leads to the contraction of the cleavage furrow in mitotic cells. Indirect evidence has also shown that Plk1 may regulate Cdc42 activity throu...

Ca2+ signaling is crucial for regulation of sperm motility and [Ca2+]i oscillations may underlie ‘switching’ of sperm behaviors in human spermatozoa, which is believed to be important for sperm progression in the female tract. We have investigated the contribution of membrane potential (Vm) and the sperm Ca2+ channel CatSper to [Ca2+]i oscillations induced by progesterone (P4). Manipulation of Vm was p...

Ca2+ signalling is critical for regulation of sperm motility. [Ca2+]i oscillations, which may underlie observed ‘switching’ of sperm behaviors, occur in human spermatozoa stimulated with progesterone. Our work aimed to investigate the potential contribution of changes in membrane potential, leading to cyclical activation of voltage dependent Ca2+-influx pathways, to [Ca2+]i oscillations. Spermatozoa we...

Epimutations are heritable defects in epigenetic programming that do not involve changes in the underlying DNA sequence and may or may not impact gene expression. Epimutations can occur naturally, but are more likely to be induced by environmental factors that disrupt the normal epigenome. Previous studies have shown that the use of assisted reproductive technologies (ART) can induce epimutations in the offspring produced. We chronicled the occurrence of epimtuations in mice p...

GnRH neurons represent the primary neuroendocrine link between the brain and the rest of the reproductive system, and traditionally it has been assumed that a single population of GnRH neurons controls both pusatile LH release as well as the preovulatory LH surge. This view has profoundly influenced our strategies for contraception and for the treatment of infertility in women. Recent data from our laboratory, however, questions the validity of this fundamental assumption. Usi...

Introduction: The chemotherapy agent etoposide is a topoisomerase II (topo II) inhibitor, and is considered safe to administer during pregnancy. However, assessment of its effects on the developing ovary, when germ cells are undergoing initiation of meiosis and forming follicles, has been limited. We have investigated this using ovarian tissue culture.Methods: E13.5 mouse ovaries were cultured for 12 days on an agar block, with etoposide added for the fi...

Introduction: Primary spermatogenic failure is the commonest cause of male infertility. Changes in Sertoli and germ cell function may be reflected in the testicular interstitial fluid (TIF) proteome and its analysis may provide insights into the pathophysiology. Microdissection testicular sperm extraction (microTESE) provides sperm for ICSI in ~50% of non-obstructive azoospermia (NOA) cases. As the first step in constructing a diagnostic approach for broader application in NOA...