Structure of the shell and tertiary membranes of eggs of softshell turtles (Trionyx spiniferus)
Structure of the shell and tertiary membranes of eggs of softshell turtles (Trionyx spiniferus)
复制标题
鳖（Trionyx spiniferus）蛋壳和三级膜的结构
作者：
M. Packard;G. C. Packard
刺鳖的卵是坚硬的钙质球体，平均直径为2.5厘米。蛋壳在形态上与鸟类的蛋壳非常相似。外结晶层由文石形式的碳酸钙的大致柱状聚集体或壳单元组成。每个壳单元在其底部逐渐变细到有点圆锥形的尖端。晶体层的内部是两层三级卵膜：外壳膜和内壳膜。外壳膜牢固地附接到壳体的内表面，并且两个膜接触，除了在气囊处，在气囊处内壳膜与外壳膜分离。两种膜都是多层的，内壳膜比外壳膜表现出更多的纤维结构。蛋壳中有许多气孔，这些气孔通常发生在四个或更多个壳单元的交叉处。
Eggs of the turtle Trionyx spiniferus are rigid, calcareous spheres averaging 2.5 cm in diameter. The eggshell is morphologically very similar to avian eggshells. The outer crystalline layer is composed of roughly columnar aggregates, or shell units, of calcium carbonate in the aragonite form. Each shell unit tapers to a somewhat conical tip at its base. Interior to the crystalline layer are two tertiary egg membranes: the outer shell membrane and the inner shell membrane. The outer shell membrane is firmly attached to the inner surface of the shell, and the two membranes are in contact except at the air cell, where the inner shell membrane separates from the outer shell membrane. Both membranes are multi‐layered, with the inner shell membrane exhibiting a more fibrous structure than the outer shell membrane. Numerous pores are found in the eggshell, and these generally occur at the intersection of four or more shell units.