金乌贼纳精囊组织结构及其精子的储存和利用

为揭示金乌贼精子进入纳精囊及产卵过程中的精子利用方式,丰富金乌贼繁殖生物学研究内容,本研究利用实验生态学和组织切片技术,检测了交配后不同时间段雌性口膜表面精子囊和纳精囊中精子数量的变化,观察分析了雌性金乌贼纳精囊的组织结构。结果显示,金乌贼纳精囊位于繁殖期雌性个体口膜腹面的突起处,共1对。纳精囊开口于口膜内表面,通过一根中央管连通整个纳精囊。中央管内壁含有大量褶皱和纤毛。在中央管两端,有12~20个储精小囊与之相连。储精小囊四周具有发达的环肌,其中储存有大量精子,并且大部分精子头部均朝向腔室内壁。完成一次交配后,雌性金乌贼对精子囊和纳精囊中精子的利用可以分为三个阶段,主要利用精子囊中的精子(交配后1~2 d);由利用精子囊中的精子向纳精囊中的精子过渡(交配后2~3 d);主要利用纳精囊中的精子(交配后3 d以上)。研究表明,从精子囊释放出的精子进入雌性口膜表面的褶皱中,通过自身运动到达纳精囊。进入纳精囊的精子通过自身运动及中央管内壁纤毛的摆动进入储精小囊,其中大部分精子头部朝向储精小囊内壁有规律地分布。在产卵过程中,雌性优先利用精子囊中的精子,而在精子囊中精子不足时,纳精囊通过肌肉收缩以及纤毛摆动将其中的精子逐渐释放出来,卵子在雌性口膜附近完成体外受精。

Histological structure of the seminal receptacle, sperm storage and utilization in the golden cuttlefish (Sepia esculenta)

The changes in the spermatozoa number in spermatangia and seminal receptacles at different times after copulation, and the structure of the seminal receptacle were examined by using experimental ecology and tissue section techniques to reveal the mechanism of sperm storage in seminal receptacle and sperm utilization during oviposition. The results showed that paired seminal receptacles were located in the raised ventral portion of the buccal membrane, and opened inside the buccal membrane. The entire seminal receptacle was connected by a central duct, which had many folds and cilia on its inner surface. Each seminal receptacle had 12-20 sperm storage bulbs surrounded by circular muscles. A large number of spermatozoa were stored in sperm storage bulbs, and the heads of most spermatozoa faced toward the inner surface of sperm storage bulbs. After one copulation, the utilization of spermatozoa in spermatangia and seminal receptacles could be divided into three stages: ① the utilization of spermatozoa mainly from spermatangia (1-2 d after copulation);② the transition from the utilization of spermatozoa in spermatangia to spermatozoa in seminal receptacles (2-3 d after copulation);③ the utilization of spermatozoa mainly from seminal receptacles (more than 3 d after copulation). These results suggest that spermatozoa released from the spermatangia reached the seminal receptacles through the folds on the surface of the female buccal membrane. Spermatozoa entered the sperm storage bulbs through self-movement and cilia fluttering on the inner surface of the central duct. The distribution of spermatozoa inside the sperm storage bulbs was highly regular, and the heads of most spermatozoa faced toward the inner surface of the sperm storage bulbs. During spawning, females preferred to use spermatozoa from spermatangia to fertilize their eggs. When spermatozoa in spermatangia were insufficient, spermatozoa in seminal receptacles were released gradually by muscle contraction and cilia fluttering, and ova were fertilized externally near the female buccal membrane.