(n.) A more or less spherical and transparent mass of granular protoplasm, which by a process of multiplication and growth develops into a mass of cells, constituting a new individual like the parent; an egg, spore, germ, or germ cell. See Illust. of Mycropyle.
(n.) One of the series of egg-shaped ornaments into which the ovolo is often carved.
Example Sentences:
(1) A specimen of a very early ovum, 4 to 6 days old, shown in the luminal form of imbedding before any hemorrhage has taken place, confirms that the luminal form of imbedding does occur.
(2) The results indicate that the sperm swelling test and the zona-free hamster ovum penetration assay are evaluating different functional qualities of sperm that are apparently not associated with each other.
(3) This study documents a molecular change in the murine ovum related to its exposure to oviductal fluid.
(4) The OCI-related membrane appeared a cause of OCI interference with fimbrial ovum capture by preventing the contact between the fimbrial cilia and the cumulus oophorus.
(5) Also, for determination of the fertilizing capacity of the semen, a zona-free hamster ovum penetration test was done in 49 men, while 14 men were studied by determination of the fertilization of human oocytes in vitro.
(6) The antiprogesterone RU 486 was utilized to evaluate the possible role of progesterone in ovum maturation, ovulation, fertilization, and embryo cleavage.
(7) It is suggested that the beta inhibitory activity of the uterus and the alpha excitatory activity of the rest of the oviduct are involved in the regulation of ovum transport.
(8) Among antigens possible unique to the reproductive process, sperm antigens, antigens of seminal plasma and of the ovum, antigens of placental hormones and of placenta specific proteins appear suitable targets of the production of fertility regulating vaccines.
(9) The preovulatory surge of gonadotropins activates a cascade of proteolytic enzymes resulting in the rupture of the follicular wall and the release of a fertilizable ovum during ovulation.
(10) The development of vaginal ultrasound transducers has facilitated ovum pick-up (OPU) by providing higher precision and less trauma than are found with laparoscopy and other ultrasound-assisted techniques.
(11) In Johnson v. Calvert, a surrogate mother in California failed to gain custody of the child she bore after gestating an embryo from the ovum and sperm of the couple who hired her.
(12) Risk factors that may theoretically alter ovum quality or the hormonal environment include ovulation induction, fertilization in vitro, delayed ovulation, and transperitoneal ovum migration.
(13) Thus, spermatozoa deposited in the vicinity of the USHG immediately following oviposition (to simulate a release of spermatozoa from this region) can be transported to the infundibulum and effectively fertilize the next ovum ovulated.
(14) However, they do not as yet permit a judgment as to the degree that ovum pickup through a fistula was impaired.
(15) We evaluated the differences between this group and those patients presenting either with a blighted ovum or beyond the first trimester, as well as the outcome of those patients with spotting early in gestation.
(16) It is too soon to learn whether this method will be reversible, but use of silastic should prevent adhesions while providing another mechanical barrier between ovum and sperm.
(17) Indomethacin was effective in preventing follicular rupture and ovum extrusion when administered simultaneously with gonadotropin.
(18) A 33% clinical pregnancy rate per ovum pick-up was achieved with the Buserelin-hMG treatment.
(19) The pregnancy rates were higher than a matched IVF series in the male factor and female ASAB groups and reached statistical significance for the ovum donation group.
(20) Lamellar structures, therefore, are considered to be storage material chiefly used in the second half of the cleavage for developmental processes in the rat ovum.
Parthenogenesis
Definition:
(n.) The production of new individuals from virgin females by means of ova which have the power of developing without the intervention of the male element; the production, without fertilization, of cells capable of germination. It is one of the phenomena of alternate generation. Cf. Heterogamy, and Metagenesis.
(n.) The production of seed without fertilization, believed to occur through the nonsexual formation of an embryo extraneous to the embrionic vesicle.
Example Sentences:
(1) O. puertoricensis did not exhibit autogeny or parthenogenesis.
(2) Cyclical parthenogenesis exaggerates the force of selection relative to recombination and will therefore enhance interlocus effects.
(3) Fertilization anomalies (possibly increased by in vitro procedures) were recorded: 1.6% of embryos resulted from parthenogenesis and 6.4% were polyploid (mainly polyspermic).
(4) Now, productive colonies of these lizards, which have remarkably little genetic variation, can be readily established and used not only for research on parthenogenesis but also for many kinds of experiments for which reptile systems are desirable.
(5) This rapid and extensive range expansion provides strong evidence that parthenogenesis can be a successful strategy for lizards in an environment with low and unpredictable rainfall.
(6) We used a comparison between cleavage rates and fertilization rates according to chromosomal analysis of oocytes to estimate the parthenogenesis frequency.
(7) These populations are thus panmictic, and most likely reproduce by cyclical parthenogenesis.
(8) Rickettsia-like maternally inherited bacteria have been shown to be involved in a variety of alterations of arthropod sexuality, such as female-biased sex ratios, parthenogenesis, and sterility of crosses either between infected males and uninfected females or between infected individuals (cytoplasmic incompatibility).
(9) There was no significant difference in parthenogenesis between any of the culture media and it appears to be a function of the strain of mice and the timing between human chorionic gonadotropin (hCG) injection and ovum collection.
(10) Parthenogenesis frequency was increased by male sexual rest.
(11) The causes for the variability of parthenogenesis indices in the polyploid clones are discussed.
(12) In vitro fertilization enabled the study of lethal (parthenogenesis) or sublethal (triploidy, monosomy and trisomy) chromosomal abnormalities in man.
(13) Methylamine appeared to activate oocytes, and most of them developed by haploid parthenogenesis.
(14) It is suggested that males are heteromorphic for the long homologue due to chromatin diminution, that occurs in the maturation division of mitotic parthenogenesis.
(15) A time-course experiment demonstrated that the extent of parthenogenetic activation in vivo following Br treatment was related to the period of time between drug injection and isolation of ova, the optimal period being 12 h. Neither Br nor MA had a direct activating effect on the oocytes as evidenced by an inability to induce parthenogenesis in vitro.
(16) Since calf thymocyte centrosomes do not support parthenogenesis, the present results suggest that duplication of the foreign centrosome is required for centrosome-induced parthenogenesis.
(17) The oocytes were prepared by a combined enzyme-mechanical method without impairing the fertility of the oocyte or inducing parthenogenesis.
(18) Comparisons are made with previously published models that deal with monogamous mating and with parthenogenesis.
(19) Parthenogenesis can only evolve in areas devoid of the generating bisexual species, because such species would prevent newly formed unisexuals from establishing clones due either to hybridization or competition.
(20) The evolutionary switch from paternal to maternal inheritance in mammals might be related to the additional dangers that parthenogenesis represents: a threat to the life of the mother as well as to the life of the fetus.