(n.) One of the two bodies or nuclei (called male and female pronuclei) which unite to form the first segmentation nucleus of an impregnated ovum.
Example Sentences:
(1) In the triploids, the 40 female chromosomes present (mouse, n = 20) were derived from a single diploid pronucleus formed after the extrusion of a first polar body, and following the monospermic fertilization of primary oocytes.
(2) Both nucleate and anucleate fragments lose the capability of transforming sperm nucleus into fully formed pronucleus sometime between 3 and 5 h after activation.
(3) A series of transgenic mice was produced by microinjection of a segment of DNA, containing 460 base pairs of the phosphoenolpyruvate (P-enolpyruvate) carboxykinase promoter-regulatory region ligated to the bovine growth hormone structural gene, into the male pronucleus of fertilized mouse eggs.
(4) Retrievals in which one or more oocytes exhibited one pronucleus were compared with retrievals in which no one-pronuclear oocytes (control) were observed.
(5) Strengthening of lethal and cytogenetic effects was only observed in case when embryos were placed in the caffeine solution, prior to onset of the first DNA replication in the male pronucleus.
(6) During the course of the formation of the male pronucleus, the subacrosomal rod and tail become detached from the head and disintegrate.
(7) Following transvaginal sonographic oocyte retrieval in vitro fertilization is performed and the fertilized (pronucleus-stage) or embryos are transferred into the tube by laparoscopy.
(8) When the drug is removed 3 h after insemination, the meiotic spindle(s) is reconstructed, the second polar body(ies) is extruded, and a female pronucleus (or micronuclei) forms.
(9) Evaluation of data concerning DNA amounts, heterochromatin contents, distribution of breaks, repair capacities in two-break sites and oxygen concentrations in mature spermatozoa revealed no contradiction to the hypothesis that the greater sensitivity of Phryne cincta is mainly due to a high degree of spiralization of the paternal pronucleus chromosomes.
(10) This conditioned medium was alone able to affect sperm penetration and male pronucleus formation in cumulus oocytes, but it did not exert any influence on denuded oocytes.
(11) Sperm centrioles were also closely associated with the male pronucleus (16-20 hr after insemination) in pronuclear stage embryos.
(12) Microtubules of unknown origin are associated with the sperm pronucleus during its migration.
(13) Correction of polyspermy through pronucleus extraction in the absence of membrane relaxants was applied to 25 polyspermic human zygotes.
(14) On the other hand, in the fully mature oocytes, which were activated by sperm penetration, the sperm nucleus was transformed into the male pronucleus.
(15) From the nine eggs used in this experiment one egg developed a pronucleus and one egg developed to a four-cell stage.
(16) Mature sperm have neither detectable centrosomes nor detectable kinetochores, and shortly after sperm incorporation kinetochores become detectable in the decondensing male pronucleus.
(17) In frogs and mammals, the oocytes are arrested at the second metaphase of meiosis whereas in echinoderms they are blocked later, at the pronucleus stage.
(18) This centrosome is attached to the centrosomal fossa, a bowl-shaped depression of the nuclear envelope of the male pronucleus.
(19) One per cent displayed a single pronucleus, and haploid chromosome complements were found in the corresponding cleaved embryos which were considered to be parthenotes.
(20) Studying the haploid portion of the male pronucleus using the hamster test reflects the process of meiosis.
Sperm
Definition:
(n.) The male fecundating fluid; semen. See Semen.
(n.) Spermaceti.
Example Sentences:
(1) A study revealed that the percentage of active sperm in semen 30 seconds after ejaculation was 10.3% when a nonoxynol 9 latex condom was used as opposed to 55.9% in a nonspermicidal condom.
(2) Here we report that sperm from psr males fertilizes eggs, but that the paternal chromosomes are subsequently condensed into a chromatin mass before the first mitotic division of the egg and do not participate in further divisions.
(3) Sperm specimens were obtained from 13 men participating in our in vitro fertilization program.
(4) Whether hen's egg yolk can be used as a sperm motility stimulant in the treatment of such conditions as asthenospermia and oligospermia is subjected for further study.
(5) Sperm were examined at 4.5 h, 8 to 9 h, and 24 to 25 h of incubation (37 degrees C, 5% CO2, and 95% air).
(6) Since the advance and return of sperm inside the tubes could facilitate the interaction of sperm with secretions participating in its maturation, the persistent infertility after vasectomy could be related to the contractile alteration that follows the excessive tubal distention.
(7) Peaks in the sperm index were preceded by 6 days with peaks in the serum testosterone concentration.
(8) Those without sperm, or with cloudy fluid, will require vasoepididymostomy under general or epidural anesthesia, which takes 4-6 hr.
(9) A sperm whale myoglobin gene containing multiple unique restriction sites has been constructed in pUC 18 by sequential assembly of chemically synthesized oligonucleotide fragments.
(10) Major limitations of the conventional sperm penetration assay are the inability to assess several aspects of sperm function (zona binding and penetration) and the absence of human ovulatory products known to influence fertilization.
(11) Couples applying to in vitro fertilization were admitted into this project when the sperm concentration was greater than 20 million per mL and motility greater than 30 per cent.
(12) To develop a new immunobead binding test (IBT) procedure that will detect sperm antibody in cervical mucus (CM), especially in very small samples of mucus.
(13) This procedure can quickly provide acrosome-reacted bull sperm for use with various in vitro fertilization procedures and for assessment of male fertility.
(14) Males were then sacrificed and organ weights, testicular spermatid counts, and cauda epididymal sperm count and sperm morphology were obtained.
(15) The freezing procedure increased sperm motility in approximately 30% of samples from both animals.
(16) The time of sperm penetration in the mouse eggs, however, was delayed for one-half to one hour when ejaculated sperm were used.
(17) The epididymis appeared distended but without any visible sperms.
(18) Liposomes of PC10 rapidly destroyed sperm motility while PC12 acrosome-reacted sperm remained motile for several h. Liposomes of PC with greater than or equal to 14-carbon fatty acyl chains had no effect on the AR or motility of sperm.
(19) Additionally, the data demonstrate that hamster sperm can remain viable for several hours after becoming immotile, and that many of the immotile sperm are capable of being reactivated.
(20) Heterogeneity in thiol content of sperm within individual samples was also observed.