During oocyte maturation, capacity and sensitivity of Ca signaling machinery increases dramatically, preparing the metaphase II (MII)arrested egg for fertilization. Upon sperm-egg fusion, Ca release from IP3-sensitive endoplasmic reticulum stores results in cytoplasmic Ca oscillations that drive egg activation and initiate early embryo development. Premature Ca release can cause parthenogenetic...

An electrophysiological method for studying the receptivity to spermatozoa of sea urchin eggs and oocytes is described. Pairs of adjacent oocytes and eggs, with intact jelly layers, were impaled and simultaneously exposed to a known concentration of spermatozoa. Two parameters were studied. The time from insemination to the first successful collision (as indicated by a step depolarization acros...

Mouse eggs fertilized in vivo were treated with cytochalasin B in vitro (5 mug/ml of culture medium) at the moment of extrusion of the second polar body (2-5, 3-0, 3-5 h after copulation). Cytochalasin B inhibits cytokinesis of the second maturation division, so that triploid digynic eggs are formed in over 50% of treated eggs. Triploid eggs were transplanted to the oviducts of recipients. On t...

Cortical granules are secretory vesicles poised at the cortex of an egg that, upon stimulation by sperm contact at fertilization, secrete their contents. These contents modify the extracellular environment and block additional sperm from reaching the egg. The role of cortical granules in blocking polyspermy is conserved throughout much of phylogeny. In the sea urchin, cortical granules accumula...

Control females of the twospotted stink bug, Perillus bioculatus (F.), and those given an artiÞcial diet mated repeatedly over their lifetimes when held with males. The average number of observed matings was 4 and 8.4 in the controls and those given the artiÞcial diet, respectively. Mating and an adequate diet are prerequisites for laying a full compliment of eggs in this insect. Virgins laid a...

This research aimed to evaluate the reproductive potential of hatchery-reared (F1) pike-perch (Sander lucioperca) broodstock fed a commercial diet with low levels long-chain polyunsaturated fatty acids (Lc-PUFA) and wild (F0) forage fish. Reproductive parameters, including pseudogonadosomatic index (PGSI), egg size, latency time, hatching rate, embryo survival, eggs’ acid (FA) composition, as w...

Parasitoids are important insects that commonly released into the environment to reduce population sizes of pest species. The lifetime reproductive success parasitoids mainly depends on host availability and mature eggs. Consequently, it is predicted female wasps must balance risk egg or (time) limitation with maximized fecundity. Typically, synovigenic females, which continue eggs throughout t...

Amphibian eggs normally require meiotic maturation to be competent for fertilization. A necessary prerequisite for this event is sperm binding, and we show that under normal physiological conditions this property is acquired at, but not before, meiotic maturation. Immature oocytes do not bind sperm, but injection of total egg poly(A)+ mRNA into immature oocytes confers sperm binding in the abse...

Stag3, a meiosis-specific subunit of cohesin complex, has been demonstrated to function in both male and female reproductive systems in mammals. However, its roles during oocyte meiotic maturation have not been fully defined. In the present study, we report that Stag3 uniquely accumulates on the spindle apparatus and colocalizes with microtubule fibers during mouse oocyte meiotic maturation. De...