杨氏鱼(Youngolepis)吻部网状骨质管的研究

本文描述了我国云南曲靖早泥盆世总鳍鱼——杨氏鱼(Youngolepis sp.)吻部网状骨质小管管壁电镜结构、元素成分、整个系统的分支状况以及它与膜质骨、侧线系统的关系,推测其功能是为吻部神经和血管提供通道.文中认为杨氏鱼与肺鱼共同具有 rostral tubuli 这一特征;将杨氏鱼吻部神经分支与骨鳞鱼、孔鳞鱼、肺鱼及两栖类进行了比较,指出杨氏鱼的眼浅支分支进入鼻囊这一特点.

ON THE MESHWORK OF THE BONY TUBULES IN THE ROSTRUM OF YOUNGOLEPIS

1. The walls of the tubules are composed of perichondral bone mainly contained the elements: P and Ca. But the internal surfaces of the walls contain Fe, Al, Si besides P and Ca permeatLng through the walls during the period of the fossil formation, the outside walls are surrounded by quartziferous materials. There are almost no rooms between the walls of the tubules and the dermal bone sometimes, also the cavities of the tubules communicate with the spaces of the sponge bone in the dermal bone in some places. 2. The meshwork of the tubuks mainly supply the passages for the nerves: r. ophthalmicus superficialis, n. ophthalmicus profundus, r. buccalis and r. maxillaris; also for the vessels in the rostrum. The features of the branching and courses of the nerves (bony tubules too) are as follows: (1) R. s. o. (c. r. s. o)(r. o. lat in Chang1982) has branches accompanying n. pr. and entering into the cavity of nasal capsule. They leave the capsule afterwards and innervate the supraorbital lateral-line canals. (2) N. pr (c. pr in Chang, 1982) supply the dorsal-lateral part of the snout. There may be a prenasal anastomosis between the ventraI branch of n. pr and medial terminal branch of the r. palatinus. (3) Branches of r. buccalis (c. r. buc) merge from the ventral side of the snout to innervate the infraorbital lateral-line canals. (4) The r. maxillaris and the r. buccalis supply the lateral part of the snout. All the tubules undergo repeated further division to form the meshwork in the rostrum. 3. In comparison with osteolepiform, porolepiform, lungfishes and amphibians, the entering of branches of r.s.o. into the nasal capsule is the salme as those in lungfishes in which living this feature is definitely mentioned. 4. Is the meshwork something like roatral tubuli in lungfishes? Based on the analysis of the structues of the walls, the courses, the function and the close relations to the lateral-line canals, and the dermal bone, referring to the defintion of this organ given by previous authors (Campbell and Barwick 1986), the answere would be in the affirmative. Chang (1991) has mentioned this character as a feature shared by Youngolepis, dipnoans and porolepiforms. But the amount of the tubules in Youngolepis is less than those in lungfishes. We may take this difference as the character of this group Youngolepis-Powichthys. the further study is needed. The other problem left is the relation ship between the tubuli and the group of pores for nerves to cutaneous organ.