Ultrastructure of the External Egg Envelopes in Two Cobitid Fishes (Cobitidae)

미꾸리과 어류 2종에 대한 난막의 미세구조

The full-grown oocyte envelope of the two spined loaches, Niwaella multifasciata and Kichulchoia brevifasciata, was examined by electron microscopy. The oocyte is surrounded by its envelope, and an external modification (an adhesive structure) in the surface of the envelope is present. The envelope consists of two layers, a zona radiata externa which is the site of the adhesive structure, and a zona radiata interna, which has heterogeneous, electron-dense multi layers. The surface (zona radiata externa) of the envelope in N. multifasciata is equipped with short villuslike protuberances, which have a length of 1.5~2.5 ${\mu}m$ and are separated from each other by a distance of 2~2.5 ${\mu}m$. In contrast, K. brevifasciata has undulating or wave-like structures that extend over the entire oocyte surface. The waves are 1.5~2.5 ${\mu}m$ in length and are separated a distance of 2.5~3.3 ${\mu}m$ from each other.

미꾸리과 어류 2종 수수미꾸리 Niwaella multifasciata, 좀수수치 Kichulchoia brevifasciata의 성숙란에 대하여 난막구조를 조사하였다. 성숙란의 난막 (egg envelope)은 부착구조 (adhesive structure)가 부착하는 zona radiata externa와 여러 전자밀도층을 가지는 zona radiata interna층으로 구성되어 있다. 수수미꾸리의 zona radiata externa는 짧은 융모형태 (short villus-like protuberance)의 구조를 가지며 길이는 약 1.5~2.5 ${\mu}m$로서 2.0~2.5 ${\mu}m$ 간격으로 배열하고 있었다. 반면에 좀수수치는 물결모양 형태 (wave-like structure)를 가지는데 길이는 약 1.5~2.5 ${\mu}m$ 크기로 서로 2.5~3.3 ${\mu}m$ 간격으로 배열되어 있다.