馬蹄の走査電子顕微鏡による観察

ウマの蹄について，とくにその表皮層と真皮層の構造を走査型電子顕微鏡を用いて観察し，その所見を従来の光学顕微鏡的所見と比較検討した。観察は蹄の各部から小塊を切り出し， 1%酢酸液または飽和水酸化バリウム液に浸漬し，蹄表皮部と蹄真皮部に分離してそれぞれについて行なった。主な所見は以下のとおりであった。
1. 走査電子顕微鏡では，真皮の真皮乳頭ならびに真皮葉の立体的構造がよく観察された。点皮乳頭は一般に糸状を呈しているが，蹄冠真皮乳頭はとくに長糸状であり，蹄底および蹄叉の乳頭は短かく，長円錐状であった。乳頭の皮質と髄質の細胞は角質化の進行とともに扁平化し，最後は線維化した。真皮葉は第1次葉から第2次葉を派出し，それぞれ対応する表皮葉と嵌合していた。真皮葉の外面は胚芽層の細胞で被われていた。
2. 蹄表皮の角細管ならびに表皮葉の構造がよく観察された。角細管の構造と分布は蹄表皮の部位によって多少異なっており，とくに蹄壁内層が中層に移行する部位ならび白帯に隣接する蹄底表皮には，小型の角細管が多く認められた。角間質は線維様構造物が凝縮したような状態で示され，その中に走向の異なる粗大な線維様構造物の層が認められた。
3. 蹄叉表皮は蹄壁，蹄底の表皮に比べて角質化が劣り，角間質に多量の弾性線維が認められた。白帯部における蹄壁表皮と蹄底表皮の結合部は，粗大な線維様構造物によって充填されていた。

Three-dimensional structures of the equine hoof were examined by means of a scanning electron microscope. Prior to the examination, small blocks of materials taken from various parts of the hoof were separated in epidermis and corium layer respectively, by maceration with 1% acetic acid or saturated barium hydroxide solution. The findings obtained were compared to the usual histological pictures. The following results were obtained.
1. The appearance of the papillae and laminae of the corium showed clearly under the scanning electron microscopy. The structure of the papillae was in principle the same over the entire corium of the hoof, but the coronary papillae were longer than those of the sole and the frog. The cellular elements surrounding the papillae became flat-formed and resulted in a fibrilar-form by the process of cornification.
2. The epidermal laminae and horn tubes of the epidermis also revealed clearly. The epidermal laminae of the wall run in parallel raws on the inside of the wall from the coronal groove to the ventral edge. They formed the secondary epidermal laminae. These epidermal laminae were interdigitated tightly with the corresponding epidermal laminae.
3. The corona, sole and frog epidermis had numerous horn tubes with the corresponding papillae. The entrance of the horn tubes showed as a funnel-shaped opening. The intertubular horns were a highly keratinized dense tissue. The thin layers of incompletely keratinized tissue run in layers in this horny matrix.
4. The epidermis of the frog was different from the one of the wall and the frog. It was composed of incompletely keratinized horn tubes and intertubular horns, which composed a network of elastic fibers. The junction of the wall and the sole at the white line was tightly connected by gross fibrous elements.