The yolk nucleus in young oocytes of Neomacheilus barbatulus (L.) (Teleostei, Cobitidae) (author's tranls).

The yolk nucleus in the young oocytes of the freshwater teleost Noemacheilus barbatulus (L.) was investigated by electron microscopy. Yolk nuclei are only found in stage I. They consist of nucleolar substance, mitochondria and partly of dictysomes. The nucleolar material leaves the nucleus through the pores of the nuclear membrane and gets into the juxtanuclear cytoplasm. It mainly consists of ribonucleic acid. The yolk nuclei of Noemacheilus doesn't have any relations to the formation of yolk.