Oocyte maturation arrest is a complex problem not clearly understood; only few cases showing a complete oocyte maturation failure has been reported previously, still the exact incidence remains unknown. Failure to resume meiosis (a specialized type of cell division that reduces the chromosome number by half) in vivo may arise at one of the following three levels: absent or incomplete luteinizin...

In Xenopus somatic cells, the somatic-type 5S RNA genes replicate early in S phase, bind the transcription factor TFIIIA, and are expressed; in contrast, the late replicating oocyte-type genes do not bind TFIIIA and are transcriptionally inactive. These facts support a model in which the order of replication of the somatic-type versus the oocyte-type 5S genes causes their differential expressio...

The two questions posed by Tesarik (1998) and Swann et al. (1998) on the nature of sperm factor are: (i) if glucosamine6-phosphate deaminase is not the ‘so-called oscillogen’, as shown by the recombinant studies of Wolosker et al. (1998), what is the nature of sperm factor?; and (ii) is there a dual mechanism for oocyte activation involving signals from soluble sperm factors together with signa...

BACKGROUND Race and ethnicity are one of the newly investigated patient-related prognostic factors that might affect the outcome of assisted reproduction techniques. To our knowledge no data currently are available on the effect of race on oocyte donation outcome. MATERIALS A retrospective, matched cohort study was performed in a private infertility centre evaluating 1012 Black, South-East As...

In spite of great efforts, the mechanisms for postovulatory oocyte aging are not fully understood. Although our previous work showed that the FasL/Fas signaling facilitated oocyte aging, the intra-oocyte signaling pathways are unknown. Furthermore, the mechanisms by which oxidative stress facilitates oocyte aging and the causal relationship between Ca2+ rises and caspase-3 activation and betwee...

Sperm chemotaxis in mammals have been identified towards several female sources as follicular fluid (FF), oviduct fluid, and conditioned medium from the cumulus oophorus (CU) and the oocyte (O). Though several substances were confirmed as sperm chemoattractant, Progesterone (P) seems to be the best chemoattractant candidate, because: 1) spermatozoa express a cell surface P receptor, 2) capacita...

The development of the head and tail regions of the Drosophila embryo is dependent upon the localized polar activation of Torso (Tor), a receptor tyrosine kinase that is uniformly distributed in the membrane of the developing embryo. Trunk (Trk), the proposed ligand for Tor, is secreted as an inactive precursor into the perivitelline fluid that lies between the embryonic membrane and the vitell...