Scanning Electron Microscopy of Shell Formation in Hen's Eggs

鶏卵の卵殻形成の機構が,走査電子顕微鏡下で形態的に観察された.

卵管子宮部に下降した直後の卵は,卵殼膜のみに包まれた状態であった.卵殼の形成が始まると,まず卵殼膜表面に微細な粒子が沈着した.ついで卵殻膜の表面の所々に凝塊様隆起が現われた.この隆起は主として有機性物質より成り,石灰沈着の核のような作用をした.後にこの有機性基質の回りに石灰沈着が進み,乳頭状の突起となった.これが卵殼乳頭層の乳頭突起である.乳頭突起は次第に丘状に発達し,最後にはお亙いにゆ合して一層の石灰層,すなわち乳頭層となった.

乳頭層の形成後は,石灰沈着が乳頭突起の上に,卵殼表面に放射状に進み,卵殼海綿層が形成された.卵殼海綿層の形成は徐々に行なわれた.

The morphological mechanism of the shell formation of hen's eggs was observed in developing eggs in the uterus by scanning electron microscopy. The shell formation was started in the egg just after the egg had arrived at the uterus. The first indication of the shell formation was the deposition of small sand-like granules on the shell surface. The subsequent indication of the shell formation was the appearance of small-sized organic protrusions on the shell surface. These protrusions increased in size as the shell formation advanced and formed nuclei of calcification. The deposition of calcium salts progressed around the organic protrusions, and mammillary knobs were formed. Previous organic concretions were encrusted by the deposition of calcium and became a central organic core, which was located at the center of the mammillary knob. Mammillary knobs were first small in size and later increased in size progressively. At last, they fused with one another to form a mammillary layer. After the formation of the mammillary layer, a spongy layer developed successively on the mammillary knob. It became thick with additional deposition of calcium salts in a radial direction.