TY  - JOUR
A1  - Franke, Werner W.
A1  - Scheer, Ulrich
T1  - The ultrastructure of the nuclear envelope of amphibian oocytes: a reinvestigation. II. The immature oocyte and dynamic aspects
N2  - No abstract available
Y1  - 1970
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-32102
ER  - 
TY  - JOUR
A1  - Franke, Werner W.
A1  - Scheer, Ulrich
T1  - The ultrastructure of the nuclear envelope of amphibian oocytes: a reinvestigation. I. The mature oocyte
N2  - 1 n order to review the contradictory statements on the ultrast ructure of the nuclear envelope, a study was undertaken combining section and negat ive stai ning electron microscopy on manually isolated oocyte nuclei and nuclear envelopes from six amphibian species including Anura as well as Urodela. The a ppeara nce of the negatively stained iso lated nuclear envelopes is described in deta il and the dependence on the preparation co nditions used is emphas ized . Pore complex structures such as pore perimeter, central granule, an nul ar components, interna l fibrils, and annu lus-attached fibrils could be identified by both techniques, negat ive staining and sect ions. Comparative studies show that no marked diffe rences ex ist in the structural data of the nuclear envelope among the investigated amphibians and the significance of the structural components is discussed. A model of the nuclea r pore complex based on the findings of the present investigation is prese nted.
Y1  - 1970
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-32098
ER  - 
TY  - JOUR
A1  - Scheer, Ulrich
A1  - Franke, Werner W.
T1  - Negative staining and adenosine triphosphatase activity of annulate lamellae of newt oocytes
N2  - Semi -iso la ted annul a te lamellae were prepared from single newt oocy tes (Triturus alpestris) by a modified Call a n-T omlin technique. Such preparations were examined with the electron mi croscope, and the negative sta ining a ppearance of th e a nnulate lamellae is described . The annul a te lamellae can be de tected either adhering to the nuclear envelope or being detached from it. Sometimes they a re obse rved to be connected with slender tubular-like structures interpreted as pa rts of the endoplasmic reti culum. The results obta ined from negativ e sta ining a re combined with those from sections. Especially, the structural data on th e a nnula te lamellae and the nuclear envelope of the very same cell were compa red . Evidence is presented th a t in the oocytes studied the two kinds of porous cisternae, n amely a nnul a te lamellae and nuclear envelope, a re markedly distinguished in that the annul a te lamellae ex hibit a much higher pore frequency (generally about twice tha t found for the corresponding nuclear envelope) and have al so a rela tive pore area occupying as much as 32 % to 55 % of th e cistern al surface (compa red with 13 % to 22 % in the nuclear envelopes). T he pore di ame ter a nd all other ultras tructural details of the pore complexes, however, a re equi valent in both kinds of porous cisternae. Like the annuli of the nuclear pore complexes of various a nimal and pl ant cells, the a nnuli of the a nnula te lamellae pores reveal al so an eightfold symmetry of their subunits in negatively stained as well as in ectioned ma teria l. Furthermore, th e a nnul a te lamellae a re shown to be a site of activity of the Mg-Na-Kstimul a ted ATPase.
Y1  - 1969
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-32087
ER  -