三疣梭子蟹卵巢发育过程中雌二醇的免疫定位和变化

摘要

雌二醇(estradiol,E2)是甲壳动物体内重要的性类固醇激素,对其卵巢发育和卵黄发生起着十分重要的调控作用.本实验采用免疫组织化学方法系统研究了三疣梭子蟹(Portunus trituberculatus)卵巢发育过程中E2在卵巢、肝胰腺、胸神经节、脑神经节和大颚器中的分布及变化.结果表明:(1)蟹卵巢中E2的免疫阳性主要分布于滤泡细胞和卵巢发育中后期的卵母细胞细胞质(Ⅱ-Ⅴ 期),卵巢发育过程中卵母细胞细胞质和细胞核中的E2免疫阳性均为先上升后下降的趋势,最大免疫阳性分别出现在IV期和Ⅱ-Ⅲ期,滤泡细胞中始终存在较强的E2免疫阳性;(2)肝胰腺中的E2免疫阳性主要分布于F细胞及R细胞细胞核中,R细胞细胞核中的E2免疫阳性从Ⅲ期开始显著下降,F细胞中始终存在较强的E2免疫阳性;(3)卵巢发育(Ⅰ-Ⅴ期)的神经组织,E2主要分布于胸神经团的神经细胞和神经髓质以及脑神经节神经细胞细胞核内,其中脑神经节神经细胞细胞核中始终保持着强免疫阳性,卵巢发育早期(Ⅰ-Ⅱ期)胸神经团中的神经髓质中为E2中等免疫阳性,神经细胞中一直为弱免疫阳性;(4)就大颚器而言,E2强免疫阳性始终存在于大颚器腺细胞的核仁以及细胞核周围的细胞质内.以上结果表明,E2在三疣梭子蟹卵巢、肝胰腺、神经组织和大颚器中广泛分布,且免疫阳性与卵巢发育具有一定的相关性,E2可能通过作用于多个靶器官来调控三疣梭子蟹的卵巢发育.%17β-Estradiol (E2) is among the most important sex steroid hormones during ovarian development and vitellogenesis in crustaceans. In this study, an immunofluorescence assay was used to identify the immunopositive distribution and variations in E2 in the ovary, hepatopancreas, thoracic ganglia, brain ganglion, and the mandibular organ during ovarian development in the swimming crab,Portunus trituberculatus. The results showed that E2 was mainly distributed in the follicular cells and the cytoplasm of late-stage oocytes (Ⅱ–Ⅴ). Follicular cells stained strongly positive for E2 at all ovarian stages; the immunoreactivities of E2 in the oocyte cytoplasm and nucleus trended as "low-high-low", and maximum positive staining appeared during ovarian stage Ⅳ and stages Ⅱ–Ⅲ, respectively. In the hepatopancreas, E2-positive staining was mainly distributed in F cells and R nuclei, and E2 immunoreactivity in the R nucleus tended to decrease from stages Ⅲ to Ⅳ. However, strong positive E2 immuno-reactivity was always detected in F cells at all ovarian stages. E2 was mainly distributed in neurons, the nerve medulla of thoracic ganglia, and cell nuclei of cerebral ganglion nerve cells during the early stages of ovarian de-velopment (Ⅰ–Ⅱ). E2 immunore activity in the nerve medulla of the thoracic ganglion was moderately positive, where as neurons were always weakly positive. Strong positive E2 staining was always distributed in the nuclei of mandibular gland cells and the cytoplasm around mandibular gland cellnuclei. These results suggest that E2 is widely distributed in the ovary, hepatopancreas, thoracic ganglion, cerebral ganglion, and mandibular gland of P. trituberculatus, and a correlation was detected between E2 immunoreactivity and ovarian developmental stage. E2 may act through multiple target organs to regulate ovarian development in P. trituberculatus.