Ovarian fluid plays an essential role in attachment of Eurasian perch, Perca fluviatilis eggs

Eggs of the Eurasian perch, Perca fluviatilis, are strongly attached to each other to form 0.5–5.5 m long and 1–6 cm wide floating jelly strands or ribbons. The processes involved in the initiation of egg attachment were investigated in the present study. Eggs are released together with small amounts of ovarian fluid. When the eggs come in contact with water, a fibrous jelly-like structure is formed by interactions between proteins of the ovarian fluid and proteins of the zona radiata externa (ZRE) leading to the egg attachment with each other. This mechanism is unique in teleost fish and is described for the first time in the present paper.