Karyosome

Karyosome refers to the chromatin material inside the cell nucleus when the cell is not undergoing meiotic division. It appears to be a dense mass in the middle of the cell and is often mistaken for the nucleolus. 
The karyosome or karyosphere is particularly known for its role in oogenesis. It seems to form at the diplotene stage, or in the first meiotic prophase. It is formed when all chromatin material form together to make a mass before the beginning of the first meiotic division. Around the mass protein granules can often be seen. 
There have been studies that point to this stage as being when genes are silenced. 