FINE STRUCTURE OF PORE-ANNULUS COMPLEX IN NUCLEAR ENVELOPE AND ANNULATE LAMELLAE OF GERM CELLS

Octagonal symmetry in the pore margin has been demonstrated in situ in annulate lamellae and the nuclear envelope of germ cells. The annular material is located to variable extent within the pore and also extends beyond the pore margin; in the latter case it may be continuous with extra-pore annular material of some adjacent pores. In thin sections of fixed material, the annular material of both the nuclear envelope and annulate lamellae appears to be composed of a matrix within which are embedded thin filaments and small granules, the disposition and interrelationship of which are described and discussed. The so-called intra-annular granule is described as consisting of a number of smaller units (similar to the granular component of the annular material) which become aggregated in the center of some pores in both the nuclear envelope and annulate lamellae. The possible significance of intra-annular granules is discussed in terms of binding and movement of macromolecules. © 1969 Springer-Verlag.