amphiastern.

/æmfɪˈæstə(r)/

Etymology: < amphi- prefix + aster n. 4.

1. Biol. [French (H. Fol 1877, in Arch. des Sci. Phys. et Nat. Apr. 441).] A spindle-shaped formation in a developing ovum, with radiations at each end, thus resembling two star-shaped figures conjoined.

ΘΚΠ

the world > life > biology > biological processes > procreation or reproduction > reproductive substances or cells > [noun] > ovum or ootid > fertilized ovum and parts

primitive streak1833

mulberry mass1851

morule1857

morula1875

stirp1875

cytula1876

vegetative pole1876

genoblast1877

mulberry germ1879

parent kernel1879

vegetal pole1881

animal pole1882

amphiaster1885

oosperm1888

segmentation sphere1898

1885 Q. Jrnl. Microsc. Sci. 25 131 In Echinoderms the germinal vesicle and spot are not directly but only partially transformed into the ‘Amphiaster de rebut’ or ‘directive spindle’.

1901 G. N. Calkins Protozoa 82 A central or ‘astral’ granule..which in some cases has been seen to divide..and to form an amphiaster.

1952 G. H. Bourne Cytol. & Cell Physiol. (ed. 2) iv. 179 The importance of..amphiaster formation in mitosis and cell division.

2. Zool. A sponge-spicule with rays at each end.

ΘΚΠ

the world > animals > invertebrates > subkingdom Parazoa > phylum Porifera > [noun] > member of > parts of > sponge spicule > having rays > at each end

amphiaster1887

1887 Sollas in Encycl. Brit. XXII. 417/2 The sigmaspire becoming spined produces the spiraster;..this..by simultaneous concentration of its spines into a whorl at each end [becomes] the amphiaster.

1934 L. W. Sharp Introd. Cytol. (ed. 3) xi. 155 In animal cells the amphiastral figure commonly develops essentially as follows.

Derivatives

amphiˈastral adj. pertaining to or involving an amphiaster.

ΚΠ

1925 E. B. Wilson Cell (ed. 3) ii. 150 As far as the history of the chromosomes is concerned the anastral types of mitosis..do not differ in any important way from the amphiastral.

This entry has not yet been fully updated (first published 1933; most recently modified version published online March 2011).

单词	amphiaster
释义	amphiastern. /æmfɪˈæstə(r)/ Etymology: < amphi- prefix + aster n. 4. 1. Biol. [French (H. Fol 1877, in Arch. des Sci. Phys. et Nat. Apr. 441).] A spindle-shaped formation in a developing ovum, with radiations at each end, thus resembling two star-shaped figures conjoined. ΘΚΠ the world > life > biology > biological processes > procreation or reproduction > reproductive substances or cells > [noun] > ovum or ootid > fertilized ovum and parts primitive streak1833 mulberry mass1851 morule1857 morula1875 stirp1875 cytula1876 vegetative pole1876 genoblast1877 mulberry germ1879 parent kernel1879 vegetal pole1881 animal pole1882 amphiaster1885 oosperm1888 segmentation sphere1898 1885 Q. Jrnl. Microsc. Sci. 25 131 In Echinoderms the germinal vesicle and spot are not directly but only partially transformed into the ‘Amphiaster de rebut’ or ‘directive spindle’. 1901 G. N. Calkins Protozoa 82 A central or ‘astral’ granule..which in some cases has been seen to divide..and to form an amphiaster. 1952 G. H. Bourne Cytol. & Cell Physiol. (ed. 2) iv. 179 The importance of..amphiaster formation in mitosis and cell division. 2. Zool. A sponge-spicule with rays at each end. ΘΚΠ the world > animals > invertebrates > subkingdom Parazoa > phylum Porifera > [noun] > member of > parts of > sponge spicule > having rays > at each end amphiaster1887 1887 Sollas in Encycl. Brit. XXII. 417/2 The sigmaspire becoming spined produces the spiraster;..this..by simultaneous concentration of its spines into a whorl at each end [becomes] the amphiaster. 1934 L. W. Sharp Introd. Cytol. (ed. 3) xi. 155 In animal cells the amphiastral figure commonly develops essentially as follows. Derivatives amphiˈastral adj. pertaining to or involving an amphiaster. ΚΠ 1925 E. B. Wilson Cell (ed. 3) ii. 150 As far as the history of the chromosomes is concerned the anastral types of mitosis..do not differ in any important way from the amphiastral. This entry has not yet been fully updated (first published 1933; most recently modified version published online March 2011). < n.1885
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