Mukai Hideo, Hashimoto Koichiro, Watanabe Hiroshi
Department of Biology, Gunma University, Maebashi, Gunma 371, Japan.
Meiji Institute of Health Science, Odawara, Kanagawa 250, Japan.
J Morphol. 1990 Nov;206(2):197-210. doi: 10.1002/jmor.1052060206.
Some unusual specialized structures of the tunic and epidermis in Polyandrocarpa misakiensis were studied histologically, histochemically, and electron microscopically. The tunic is leathery, containing fibers. Dorsal epidermal cells show cytoplasmic bulges at their apical ends, suggesting formation of tunic by the epidermis. Both siphons are characterized by a well-developed velum. In the dorsal mantle, especially around the siphons, numerous elongate cord-like structures of the tunic (10-30 μm in diameter) extend into the hemocoel. Each tunic cord originates from the extra-epidermal tunic, ends distally in a spade-shaped swelling, and is covered by flattened epidermal cells. The tunic cords probably act as connectors between tunic and mantle. Glomerulocytes, a kind of blood cell, are distributed throughout the hemocoel. They are disc-shaped (12-13 μm in diameter, 3 μm thick), and are characterized by a concentric fiber structure in the cytoplasm. The intracellular fibers are similar to the tunic fibers both morphologically and histochemically. The glomerulocytes appear to be derived from epidermal cells; their differentiation occurs in all regions of the epidermis. The function of glomerulocytes is unknown. Small club-shaped bodies which are intensely eosinophilic are distributed here and there in the dorsal epidermis. These eosinophilic bodies are usually located individually in epidermal pockets, and are protruded into the hemocoel. The eosinophilic body is proteinaceous and PAS-positive; it may be a secretory product of the covering epidermis. No physiological role of the eosinophilic body is yet clear. During blasto-genesis, incipient tunic cords, glomerulocytes, and eosinophilic bodies appear almost simultaneously at a stage shortly before the opening of siphons.
对三宅多雄果海鞘的被囊和表皮一些不寻常的特殊结构进行了组织学、组织化学和电子显微镜研究。被囊坚韧似皮革，含有纤维。背侧表皮细胞在顶端显示出细胞质凸起，表明被囊由表皮形成。两个虹吸管的特征是有发育良好的膜。在背侧外套膜中，尤其是在虹吸管周围，许多细长的绳索状被囊结构（直径10 - 30μm）延伸到血腔中。每个被囊索起源于表皮外的被囊，远端终止于铲形肿胀处，并被扁平的表皮细胞覆盖。被囊索可能充当被囊和外套膜之间的连接物。肾小球细胞是一种血细胞，分布于整个血腔。它们呈盘状（直径12 - 13μm，厚3μm），其特征是细胞质中有同心纤维结构。细胞内纤维在形态和组织化学上与被囊纤维相似。肾小球细胞似乎起源于表皮细胞；它们在表皮的所有区域发生分化。肾小球细胞的功能尚不清楚。小的棒状体呈强嗜酸性，散布在背侧表皮各处。这些嗜酸性体通常单个位于表皮凹陷处，并突出到血腔中。嗜酸性体是蛋白质性的且PAS阳性；它可能是覆盖表皮的分泌产物。嗜酸性体的生理作用尚不清楚。在胚胎发生过程中，初始的被囊索、肾小球细胞和嗜酸性体几乎在虹吸管开口前不久的阶段同时出现。
