Histological Studies on Gonad and Germ Cell Development of Diploid and Triploid Mud Loach (Misgurnus mizolepis)

2배체와 3배체 미꾸라지(Misgurnus mizolepis)의 생식소 발달

A Study was conducted by using a histological method to examine gonadal development in diploid and triploid mud loach, Misgurnus mizolepis. Shape of ovaries from both groups looked like a single mass however, size of triploid ovary was significantly smaller than that of diploid ovary. Testis of triploid was also similar that of diploid in shape, but it was smaller than that of diploid. Ovarian development and oogenesis in diploid were significantly more rapid than those process in triploid, and first matured eggs were observed 100-days after hatching (SL, 5.68cm). Triploid ovary from hatching to 9-month-old had external appearance of undeveloped gonad and a few of oocytes of perinucleolus stage. However, normal matured eggs like those of female diploid were observed in one 5year-old triploid fish ovary examined. Although testicular development and sperrnatogenesis of diploid were prosperous sexually, testicular development of triploid were rather retarded compare to their male diploid counterpart in spermatogenesis.

유도된 3배체 미꾸라지, Misgurnus mizolepis를 재료로 생식소 발달을 조사하여 2배체와 비교하였다. 난소 외부 형태는 융합된 하나의 낭상으로 복강을 향해 horseshoe shape으로 발달하며 짧은 수란관을 통해 비뇨생식공(urogenital pore)으로 개구되는 구조였다. 3배체 난소는 얇은 나뭇잎 모양으로 2배체에 비해 작고, 미발달되었으며, 정소는 2배체보다 다소 작지만, 외형상 2배체와 유사하였다. 난소 발달 및 난자형성과정은 2배체에서 부화 후 100일에 성숙 난소 및 성숙 난모세포가 출현하는 비교적 빠른 발달을 보인 반면, 3배체에서는 부화후 9개월까지 제1차 성장기의 난모세포가 나타났을 뿐 더 이상 발달하지 않았다. 다만, 조사된 1마리의 5년산 3배체에서는 난소내 성숙 난모세포들이 관찰되었다. 비록 정소발달 및 정자형성과정은 3배체 수컷 역시 2배체와 동일하게 진행되었지만 3배체가 2배체에 비해 각 단계별 발달 시기는 지연되었고, 생식세포 핵의 크기는 크게 나타났다.