Comparative Anatomy and Phylogeny of Cyclostomes

从功能解剖学和系统发育学的角度，对现存最原始的脊椎动物环口(七鳃鳗和七鳃鳗)进行了连续的横切面制作和研究。在七鳃鳗中，还观察到羊膜幼虫。这些环口最显著的组织学特征是出现大的血窦、分化多样的软骨和独特的红色肌肉。这些三合一尤其是呼吸器官的特征。在羊膜动物中，位于口腔和咽部之间的膜的持续运动导致口腔中的呼吸水被吸收。膜上有大的血窦、红色的肌肉和粘液腺。膜的运动主要是由红色肌肉引起的，但血窦系统作为一种水骨骼，可能在将肌肉收缩的力量转化为整体膜运动的过程中发挥重要作用。在成年七鳃鳗中，呼吸水在外部鳃之间穿梭，-PULE…更多的是颧囊。在成年人体内，血窦广泛分布，但鳃周窦突出。鳃壁红色肌肉的收缩可以通过鳃周窦中的血液顺利地输送到鳃囊，并引起颧囊的收缩和水通过鳃孔流出。水的流入可能是由于连接由典型的牙槽软骨组成的颧弓的纤维组织的弹性扩张。在八角鳗中，大的血窦出现在身体的不同区域，包括膜和鳃壁。在膜中，出现了肺泡软骨和红色肌肉，尽管它们在组织上与七鳃鳗不同。在环口动物中，具有特征的分化的肌肉和软骨系统肯定会引起呼吸运动，但血窦系统作为一种水骨骼，对于呼吸器官的正常运动可能是不可或缺的。然而，根据系统发育分析，血窦系统的出现不能被认为是环口的同形异形。较少

Serial transverse sections of the most primitive living vertebrates, the cyclostomes(lampreys and hagfishes), were prepared and studied from viewpoints of functional anatomy ana phylogeny. In lampreys, ammocoetes larvae were also examined.The most remarkable histological features of these cyclostomes were the occurrence of large blood-sinuses, diversely differentiated cartilages, and unique red muscles. These triads especially characterize the respiratory organs. In ammocoetes, the continuous movement of the velum, located between the buccal cavity and pharynx, causes incorporation of respiratory water from the mouth. In the velum, there are large blood-sinuses, red muscles, and mucocartilage. The movement of the velum is primarily caused by the red muscles, but the blood-sinus system may be important as a kind of hydroskeleton in transforming the force of muscular contraction to the overall velar movement. In adult lampreys, respiratory water shuttles between the external gill, -pore … More and branchial sac. In adults, blood-sinuses are widely distributed in the body, but the peribranchial sinus is prominent. The contraction of the red muscles of the branchial wall may be smoothly conveyed by blood in the peribranchial sinus to the branchial sac and cause contraction of the sac and outflow of the water through the gill pore. The inflow of water may be due to elastic expansion of fibrous tissues connecting branchial arches made of characteristic alveolar cartilage. In hagfishes, large blood-sinuses occur in various regions of the body, including the velum and branchial wall. In the velum, alveolar cartilage and red muscles occur, although they are histologically different from those of lampreys.In cyclostomes, characteristically differentiated muscular and cartilage systems certainly cause the respiratory movement, but the blood-sinus system may be indispensable, as a kind of hydroskeleton, for the proper movement of the respiratory organs. Based on phylogenetic analysis, however, the occurrence of blood-sinus system could not be regarded as a synapomorphy of cyclostomes. Less