(n.) The rudiment of a seed. It grows from a placenta, and consists of a soft nucleus within two delicate coatings. The attached base of the ovule is the hilum, the coatings are united with the nucleus at the chalaza, and their minute orifice is the foramen.
(n.) An ovum.
Example Sentences:
(1) Eight-week-old virgin untreated female mice were induced to ovulate using equine chorionic gonadotropin (eCG) and human chorionic gonadotropin (hCG), and were then caged with males overnight.
(2) The total content of both thyroid hormones in the oocytes increased throughout most of the ovarian cycle as the oocytes increased in size from less than 2 mg to approximately 6.5 mg by ovulation.
(3) GnRH infusion produced an immediate increase in plasma LH concentrations in the mares that ovulated during the infusion period and LH levels peaked at the time of ovulation.
(4) An experimental model was established in the ewe allowing one to predict with accuracy an antral follicle that coincidentally would either undergo ovulation (6-8 mm diameter) or atresia (3-4 mm diameter) following synchronization of luteal regression and the onset of the gonadotropin surge.
(5) We conclude that plasma LAP measurements have little value in monitoring ovulation induction therapy.
(6) The mean ovulation age for the 728 abortuses was 63.4 days (range 33--109 days).
(7) These results strongly suggest that urinary GAGs determination is a precise method for ovulation detection.
(8) These findings suggest, not only that cAMP production alone is sufficient for ovulation, but also that the receptor specificity of the cAMP production is important for the number of ovulations.
(9) These cells produce a neurohormone which stimulates ovulation.
(10) Following parturition, NONLAC cows averaged 4.0 d to negative EB nadir and 14.3 d to first ovulation.
(11) LH serum levels were measured by radioimmunoassay on 10 women who were near the time of presumed ovulation.
(12) Bactrian camels (63 female female, 8 male male) were used in the breeding season to determine the factors that will induce ovulation.
(13) A dose of 3.75 mg and even 4.0 mg of conjugated estrogen was not sufficient to inhibit ovulation.
(14) During 70 days or so from the time of recruitment until just before the beginning of the cycle during which a follicle is destined to ovulate, folliculogenesis is a continuous process dependent on gonadotrophins but independent of the fluctuations in their concentrations occurring during this time.
(15) In all patients buserelin clearly suppressed ovulation.
(16) Repeated laparoscopy in the same animal throughout the menstrual cycle showed by morphological and hormonal criteria that this technique does not significantly influence follicular growth, ovulation, luteal function or cycle length.
(17) 6-OHDA administered intraventricularly in doses 200-500 mug caused temporary blockade of ovulation.
(18) The data are expressed as percent inhibition of ovulation in the treated vs. the untreated ovaries.
(19) Circular cuts which surgically isolated the medial basal hypothalamus (MBH) from the remainder of the brain did not prevent copulation 4 to 24 h later, but did block reflex ovulation.
(20) In spite of small corpora lutea and increased follicular activity, none of the prednisolone treated heifers showed signs of oestrogen influence, and the two animals slaughtered 26 days after the start of treatment, did not ovulate or show signs of oestrus.
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.