| 单词 | pronucleus |
| 例句 | The two haploid nuclei derived from the sperm and oocyte and contained within the egg are referred to as pronuclei. Anatomy and Physiology 2013-06-19T00:00:00Z Crucially, the transferred pronuclei brought few mitochondria with them, suggesting that a resulting embryo would largely be free of any disease-causing mutant mitochondria. Reproductive medicine: The power of three 2014-05-20T04:00:00Z The egg nucleus, now known as the female pronucleus, and each body contain the reduced or haploid number of chromosomes. Being Well-Born An Introduction to Eugenics 2012-05-22T15:16:53.140Z If Gametogeny. than one spermatozoon enters, a corresponding number of male pronuclei are formed, and the subsequent development, if it takes place at all, is abnormal and soon ceases. Encyclopaedia Britannica, 11th Edition, Volume 9, Slice 3 "Electrostatics" to "Engis" 2011-02-06T03:00:53.093Z S, spermatozoön; m. pr., male pronucleus; f. pr., female pronucleus. Darwin, and After Darwin (Vol. 1 and 3, of 3) An Exposition of the Darwinian Theory and a Discussion of Post-Darwinian Questions The pronuclei then migrate toward each other, their nuclear envelopes disintegrate, and the male- and female- derived genetic material intermingles. Anatomy and Physiology 2013-06-19T00:00:00Z Then the embryologist eases a pipette into the hole and plucks out the pronuclei, twin genetic structures that result from fertilization. Reproductive medicine: The power of three 2014-05-20T04:00:00Z As soon as the nucleus of the spermatozoon, now known as the male pronucleus, reaches the interior of the egg, it enlarges and becomes similar in appearance to the female pronucleus. Being Well-Born An Introduction to Eugenics 2012-05-22T15:16:53.140Z As this is in all probability derived entirely from the nucleus of the spermatozoon, we should be almost justified in calling the nucleus of the spermatozoon the male pronucleus. Encyclopaedia Britannica, 11th Edition, Volume 9, Slice 3 "Electrostatics" to "Engis" 2011-02-06T03:00:53.093Z First, its own head rapidly increases in size, and takes on the appearance of a cell-nucleus: this is called the male pronucleus. Darwin, and After Darwin (Vol. 1 and 3, of 3) An Exposition of the Darwinian Theory and a Discussion of Post-Darwinian Questions In this way the centrosome approaches the female pronucleus, and thus finally the two nucleii are brought into close proximity. The Story of the Living Machine A Review of the Conclusions of Modern Biology in Regard to the Mechanism Which Controls the Phenomena of Living Activity Next, the researcher empties a fertilized donor egg of its genetic material and squirts the pronuclei into the hollow egg. Reproductive medicine: The power of three 2014-05-20T04:00:00Z Part of it is extruded, and part dissolved in the cell contents; only a very small part of it is left to form the basis of a fresh nucleus, the pronucleus femininus. The Evolution of Man — Volume 1 The general rule appears to be that the female pronucleus is without a centrosome, and that no centrosome appears in the female in the divisions by which the gamete arises from the progamete. Encyclopaedia Britannica, 11th Edition, Volume 9, Slice 3 "Electrostatics" to "Engis" 2011-02-06T03:00:53.093Z At the same time its tail begins to disappear, and the enlarged head proceeds to make its way directly towards the nucleus of the ovum which, as before stated, is now called the female pronucleus. Darwin, and After Darwin (Vol. 1 and 3, of 3) An Exposition of the Darwinian Theory and a Discussion of Post-Darwinian Questions FIG.40.—Completion of the process of extrusion of the chromatic material; fn shows the two chromosomes retained in the egg forming the female pronucleus. The Story of the Living Machine A Review of the Conclusions of Modern Biology in Regard to the Mechanism Which Controls the Phenomena of Living Activity This is undoubtedly derived from the spermatozoon, possibly from its nucleus only, and is called the male pronucleus. Encyclopaedia Britannica, 11th Edition, Volume 9, Slice 3 "Electrostatics" to "Engis" 2011-02-06T03:00:53.093Z If this is true, the centrosome of the zygote nucleus must be entirely derived from that of the male pronucleus. Encyclopaedia Britannica, 11th Edition, Volume 9, Slice 3 "Electrostatics" to "Engis" 2011-02-06T03:00:53.093Z Giard suggests that in some cases of apparently normal fertilization one of the pronuclei may degenerate, the resultant embryo being the product of one pronucleus only. Encyclopaedia Britannica, 11th Edition, Volume 9, Slice 3 "Electrostatics" to "Engis" 2011-02-06T03:00:53.093Z I. The second polar body has just been extruded; both male and female pronuclei contain two chromatin particles; those of the male pronucleus are becoming transformed into a skein. Darwin, and After Darwin (Vol. 1 and 3, of 3) An Exposition of the Darwinian Theory and a Discussion of Post-Darwinian Questions Now the centrosome, which is beside the male pronucleus, shows signs of activity. The Story of the Living Machine A Review of the Conclusions of Modern Biology in Regard to the Mechanism Which Controls the Phenomena of Living Activity This accounts for the fact, which has been often observed, that the female pronucleus is not surrounded by protoplasmic radiations, whereas such radiations are present round the male pronucleus in its approach to the female. Encyclopaedia Britannica, 11th Edition, Volume 9, Slice 3 "Electrostatics" to "Engis" 2011-02-06T03:00:53.093Z The fusion of the two pronuclei is sometimes effected in a manner slightly different from that described for the mouse. Encyclopaedia Britannica, 11th Edition, Volume 9, Slice 3 "Electrostatics" to "Engis" 2011-02-06T03:00:53.093Z There appears, however, to be some variation in this respect: cases have been observed in the mouse in which fusion of the pronuclei occurs before the separation of the chromosomes. Encyclopaedia Britannica, 11th Edition, Volume 9, Slice 3 "Electrostatics" to "Engis" 2011-02-06T03:00:53.093Z The chromatin in both pronuclei now forms into a skein. Darwin, and After Darwin (Vol. 1 and 3, of 3) An Exposition of the Darwinian Theory and a Discussion of Post-Darwinian Questions In Echinus, for instance, the two pronuclei fuse, and the spindle and chromosomes are formed from the zygote nucleus, whereas in the mouse the two pronuclei retain their distinctness during the formation of the chromosomes. Encyclopaedia Britannica, 11th Edition, Volume 9, Slice 3 "Electrostatics" to "Engis" 2011-02-06T03:00:53.093Z Only the female pronucleus is shown in this figure. Darwin, and After Darwin (Vol. 1 and 3, of 3) An Exposition of the Darwinian Theory and a Discussion of Post-Darwinian Questions The pronuclei have come into contact, and the spindle-system is now arranged across their common axis. Darwin, and After Darwin (Vol. 1 and 3, of 3) An Exposition of the Darwinian Theory and a Discussion of Post-Darwinian Questions The nucleus of the male gamete is not called the male pronucleus, as would be expected, that term being reserved for the second nucleus which appears in the ovum after fertilization. Encyclopaedia Britannica, 11th Edition, Volume 9, Slice 3 "Electrostatics" to "Engis" 2011-02-06T03:00:53.093Z The male pronucleus has the remains of the body of the spermatozoön adhering to it. Darwin, and After Darwin (Vol. 1 and 3, of 3) An Exposition of the Darwinian Theory and a Discussion of Post-Darwinian Questions Contraction of the skein, and formation of two U-or V-shaped chromatin fibres in each pronucleus. Darwin, and After Darwin (Vol. 1 and 3, of 3) An Exposition of the Darwinian Theory and a Discussion of Post-Darwinian Questions V. The V-shaped chromatin filaments are now quite distinct: the male and female pronuclei are in close contact. Darwin, and After Darwin (Vol. 1 and 3, of 3) An Exposition of the Darwinian Theory and a Discussion of Post-Darwinian Questions The conjugation of the pronuclei is apparently complete in VII. Darwin, and After Darwin (Vol. 1 and 3, of 3) An Exposition of the Darwinian Theory and a Discussion of Post-Darwinian Questions |
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