異常卵殻の走査電子顕微鏡下の構造

本研究は数種の異常卵殻の微細構造を走査電子顕微鏡下で調べた。観察は10％硫化ソーダで卵殻から有機質を除いた試料で行った。主な所見は以下のとおりであった。
(1) 皺状卵殻(corrugated shell)の卵殻皺の隆起部の構造は正常であったが,隆起部の間の溝状部では乳頭層の異常が顕著であり,同時に海綿層の形成不全を伴っていた。
(2) 疣状卵殻(pebbly-textured shell)は2型に大別された。一つは外卵殻膜の上に有機性凝塊が沈着し,これによって卵殻石灰質層が隆起したものであった。卵殻乳頭層に有機性凝塊に対応する大きさの陥没部が形成されており,この部の乳頭突起は異常であった。他の一つは卵殻海綿層に有機物凝塊が沈着し,これによって海綿質が隆起したものであった。海綿質層に有機物凝塊に対応する空洞が形成されていた。両者いずれの場合にも隆起部の卵殻質は粗雑であった。
(3) 斑状卵殻(mottled shell)は卵殻構造は正常であったが、卵殻質は卵殻表層と海綿層が散在的に粗雑であった。
(4) ヒビ割れ卵殻(checked shell)は乳頭層に裂け目を生じていた。裂け目は海綿層の深層に達していたが,上層では完全に修復されていた。
(5) 薄殻(thin shell)は2型に大別された。一つは海綿層の形成過程に産出されたものであり,粗雑な卵殻質を有するものであった。他の一つは卵殻質は緻密であるが,乳頭層に欠陥があって海綿層が正常の厚さに達し得ないものであった。
(6) 軟卵殻(soft shell)は乳頭層の形成過程において放出されたものであり,発達中の乳頭突起だけからなっていた。
(7) 外観的異常を伴う卵殼は共通的に乳頭層が異常であった。乳頭層の異常は乳頭突起の乳頭核の異常に起因していた。

The fine structure of various abnormal eggshells of hens were examined under scanning electron microscope. The findings are as follows.
1. Corrugated shells had remarkable and specific abnormalities in their structure. The protruded area of wrinkles was normal as for its structure and shell texture, whereas the concaved area between the wrinkles was particularly thin due to the deficiency of the spongy layer. The mammillary layer just beneath the protruding wrinkles was almost normal in structure, whereas the one of the concaved area showed no complete formation.
2. Rough and pebbly-textured shells were classified into two types. One had prominences which were made by the deposition of foreign organic masses on the shell membrane in the early stage of the formation of the mammillary knobs. In this case, various sizes of craters, in which the formation of the mammillary knobs had been extensively disturbed, were formed in the mammillary layer. Other prominences were made by the deposition of similar objects on the fairly developed spongy layer. In this case, no abnormalities of the mammillary layer were detected.
3. Mottled shells had a highly rough and very porous shell texture, particularly in the superficial layer of the shell and the spongy layer around the air pores. The remainder of the shell was normal.
4. Checked shells had internally streak-like clefts in the mammillary layer, these extended into the deep layer of the mammillary layer. These cracks had not been sealed by the addition of calcified material, so that they must have been formed in the early stage of the shell formation.
5. Thin-shelled eggs were divided into two types. One was the thin shell with large air pores during its formation and with a porous shell texture. They were expelled before the full formation of the spongy layer. Another type was the thin shell which did not develop to normal thickness due to its incomplete mammillary layer.
6. Soft-shelled eggs had only the developing mammillary knobs on the surface of the shell membrane. They were expelled prematurely in the course of the formation of the mammillary layer.
7. From the above results, it is considered that the abnormality of eggshells is caused mostly by the incomplicity of the mammillary knobs, and that the formation of the mammillary knobs is influenced by the degree of normality of the shell membrane formation.