Tetsuka Masafumi, Asada Masatsugu, Mogoe Toshihiro, Fukui Yutaka, Ishikawa Hajime, Ohsumi Seiji
Department of Agricultural and Life Science, Obihiro University of Agriculture and Veterinary Medicine, Hokkaido, Japan.
J Reprod Dev. 2004 Aug;50(4):381-9. doi: 10.1262/jrd.50.381.
This study describes the morphological and morphometrical changes associated with prepubertal ovarian development in the Antarctic minke whale (Balaenoptera bonaerensis). Ovaries were harvested from 94 immature minke whales caught in the Antarctic Ocean during the summer feeding season (December-March). Notable differences in ovarian size and morphology were found among animals. Up to 10 folds difference in ovarian weight was found among prepubertal whales of similar body size. During the prepubertal period, ovaries grew slowly and approximately doubled their weight. The morphologies of right and left ovaries were almost identical while the growth of the ovary appears to occur preferentially on the right side. The most striking morphological feature was numerous small antral follicles less than 5 mm in diameter found in ovaries of younger immature whales. The occurrence of these ovaries was highest in whales less than 6 m long and gradually decreased as body length increased. In larger whales, the occurrence of ovaries with a smaller number of follicles up to 10 mm and thick tunica albuginea increased. Thus, the ovary of the Antarctic minke whale experiences bursts of small follicular development during the early prepubertal period before becoming a more developed ovary with fewer but larger follicles, and thick tunica albuginea.
本研究描述了南极小须鲸（Balaenoptera bonaerensis）青春期前卵巢发育相关的形态学和形态计量学变化。在夏季觅食季节（12月至3月），从南极海洋捕获的94头未成熟小须鲸身上采集卵巢。在这些动物中发现了卵巢大小和形态的显著差异。在体型相似的青春期前鲸鱼中，卵巢重量相差达10倍。在青春期前阶段，卵巢生长缓慢，重量大约增加一倍。左右卵巢的形态几乎相同，而卵巢的生长似乎优先发生在右侧。最显著的形态学特征是在较年幼的未成熟鲸鱼卵巢中发现大量直径小于5毫米的小窦状卵泡。这些卵巢在体长小于6米的鲸鱼中出现频率最高，并随着体长增加而逐渐减少。在较大的鲸鱼中，卵泡数量较少、直径达10毫米且白膜较厚的卵巢出现频率增加。因此，南极小须鲸的卵巢在青春期前早期经历小卵泡发育的爆发，之后变成卵泡数量较少但更大、白膜较厚的更发达卵巢。
