Farrelly Caroline, Greenaway Peter
School of Zoology, University of New South Wales, Kensington, New South Wales, Australia 2033.
J Morphol. 1987 Sep;193(3):285-304. doi: 10.1002/jmor.1051930307.
The five gill pairs of Mictyris longicarpus have the lowest weight specific area reported for any crab. The cuticle of the gill lamellae is lined with epithelial cells which have structural features characteristic of iontransporting cells. Pillar cells are regularly distributed in the epithelium and serve to maintain separation of the two faces of the lamellae. The central hemolymph space is divided into two sheets by a fenestrated septum of connective tissue cells. The dorsal portion of the marginal canal of each lamella receives hemolymph from the afferent branchial vessel and distributes it to the lamella while the ventral portion of the canal collects hemolymph and returns it to the efferent branchial vessel. The lung is formed from the inner lining of the branchiostegite and an outgrowth of this, the epibranchial membrane. Surface area is increased by invagination of the lining which forms branching, blind-ending pores, giving the lung a spongy appearance. The cuticle lining the lung is thin and the underlyng epithelial cells are extremely attenuated, giving a total hemolymph/gas distance of 90-475 nm. Venous hemolymph is directed close to the gas exchange surface by specialised connective tissue cells and by thin strands of connective tissue which run parallel to the cuticle. Air sacs are anchored in position by paired pillar cells filled with microtubules. Afferent hemolymph is supplied from the eye sinus, dorsal sinus, and ventral sinus. Afferent vessels interdigitate closely with efferent vessels just beneath the respiratory membrane. The two systems are connected by a "perpendicular system" which ramifies between the airways and emerges to form a sinus beneath the carapace and then flows back between the air sacs to the efferent vessels. The afferent side of the perpendicular system is the major site of gas exchange. Efferent vessels return via large pulmonary veins to the pericardial cavity. P O levels were high (95.5 Torr), indicating highly efficient gas exchange.
长腕和尚蟹的五对鳃具有已知所有蟹类中最低的重量比表面积。鳃小片的角质层内衬有上皮细胞，这些上皮细胞具有离子转运细胞的结构特征。柱状细胞规则地分布在上皮中，用于维持鳃小片两面的分离。中央血淋巴腔被结缔组织细胞的有孔隔膜分成两层。每个鳃小片边缘管的背侧部分从入鳃血管接收血淋巴并将其分布到鳃小片，而管的腹侧部分收集血淋巴并将其返回出鳃血管。肺由鳃盖内膜及其外突（鳃上膜）形成。通过内衬的内陷形成分支的盲端小孔，增加了表面积，使肺呈现出海绵状外观。肺内衬的角质层很薄，其下方的上皮细胞极度变薄，使得血淋巴/气体的总距离为90 - 475纳米。静脉血淋巴通过特殊的结缔组织细胞和平行于角质层的结缔组织细束被引导至靠近气体交换表面的位置。气囊通过充满微管的成对柱状细胞固定在位。入鳃血淋巴由眼窦、背窦和腹窦供应。入鳃血管与出鳃血管在呼吸膜下方紧密交错。这两个系统通过一个“垂直系统”相连，该系统在气道之间分支，然后在头胸甲下方形成一个窦，接着在气囊之间回流到出鳃血管。垂直系统的入鳃侧是主要的气体交换部位。出鳃血管通过大的肺静脉返回心包腔。氧分压水平很高（95.5托），表明气体交换效率很高。
