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<p>The first comprehensive histological characterization was conducted of ovarian development in East Asian common octopus (<i>Octopus sinensis</i>) off Kagawa prefecture, Seto Inland Sea, Japan. Female specimens (<i>n</i> = 48) were examined to elucidate oocyte developmental stages and to establish a species-specific maturity scale. On the basis of histological observations, oocyte development was classified into eight stages: oogonia, primary follicular oocytes, secondary follicular oocytes, previtellogenic oocytes, vitellogenic oocytes, advanced vitellogenic oocytes, mature oocytes, and ovulated oocytes. Female maturity was categorized into four stages on the basis of predominant oocyte types and macroscopic characteristics of the ovary. Statistical analyses found significant differences in body weight and reproductive system index (RSI) among maturity stages. Morphometric analysis of outer follicular structures found significant changes in structure area during oocyte development, with maximum size observed during the advanced vitellogenic stage. It is noteworthy that 23.8% of immature females had sperm stored in oviductal glands, indicating that mating can occur before females reach full maturity. This represents a distinctive reproductive characteristic not previously documented in detail for this species. This study establishes essential baseline information related to the reproductive biology of <i>O</i>. <i>sinensis</i> for resource management and aquaculture development in the Seto Inland sea region.</p>

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Reproductive biology of female East Asian common octopus (Octopus sinensis): oocyte development, maturity staging, and follicular structure morphometry

  • 期刊论文

  • 发表日期：

    2025年9月30日

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  • Yasuhisa Kobayashi,
  • Masayuki Yamamoto

摘要

The first comprehensive histological characterization was conducted of ovarian development in East Asian common octopus (Octopus sinensis) off Kagawa prefecture, Seto Inland Sea, Japan. Female specimens (n = 48) were examined to elucidate oocyte developmental stages and to establish a species-specific maturity scale. On the basis of histological observations, oocyte development was classified into eight stages: oogonia, primary follicular oocytes, secondary follicular oocytes, previtellogenic oocytes, vitellogenic oocytes, advanced vitellogenic oocytes, mature oocytes, and ovulated oocytes. Female maturity was categorized into four stages on the basis of predominant oocyte types and macroscopic characteristics of the ovary. Statistical analyses found significant differences in body weight and reproductive system index (RSI) among maturity stages. Morphometric analysis of outer follicular structures found significant changes in structure area during oocyte development, with maximum size observed during the advanced vitellogenic stage. It is noteworthy that 23.8% of immature females had sperm stored in oviductal glands, indicating that mating can occur before females reach full maturity. This represents a distinctive reproductive characteristic not previously documented in detail for this species. This study establishes essential baseline information related to the reproductive biology of O. sinensis for resource management and aquaculture development in the Seto Inland sea region.