In fixed cells the nucleus seems to consist of a clear substance or karyoplasm and a network or karyomitome.    From Wordnik.com.  [I. Embryology. 1. The Animal Cell] Reference

Its structure is that of an ordinary cell-nucleus, viz., it consists of a reticulum or karyomitome, the meshes of which are filled with karyoplasm, while connected with, or imbedded in, the reticulum are a number of chromatin masses or chromosomes, which may present the appearance of a skein or may assume the form of rods or loops.    From Wordnik.com.  [I. Embryology. 2. The Ovum] Reference