鶏の頭部皮膚の毛細血管構築

産卵中の雌鶏の頭部皮膚の毛細血管構築像を,メチルメタクリレート鋳型標本によって,走査電子顕微鏡を用いて観察し,以下の所見を得た。
1. 鶏の頭部の肉冠,肉垂などの無羽域部の皮膚は,表皮の直下に極めて密性な毛細血管網を構築していた。嘴上部,前頭部,冠状部,眼険,眼険上部,頬部,側頭部などのごとく小型の羽毛を持っている皮膚も,肉冠,肉垂に劣らない密性の毛細血管網を具えていた。
2. 後頭部のごとく比較的大型の羽毛を持っている皮膚では,皮膚の毛細血管は羽包を中心に血管網を形成していた。したがって,頭部皮膚の毛細血管網の緻密性,複雑性は羽毛の大きさ,分布が関係していた。
3. 肉冠,肉垂の皮膚毛細血管網は洞様毛細血管で構築されていた。羽域部の血管網は,やや太い捻転の著しい毛細血管で糸球状に構築されていた。
4. 頭部皮膚のほぼ全体が,密性な皮膚毛細血管網で覆われていたことから,鶏体において肉冠,肉垂を含む頭部皮膚全体が,体熱放散の機能を果たしていることが推察された。

The cutaneous microvascular architectures of the head region of matured hens were examined by means of resin cast preparations with methylmethacrylate under the scanning electron microscope.

The findings obtained were as follows.
1. The unfeathered skin of the head including the comb and the wattle had vsscular networks highly complicated and very dense just beneath the epidermis. The region of the skin with downy short feathers such as the loral, the frontal, the coronal, the eyelid, the supra- and infraorbital, the temopral, and the postauricular region also had vascular networks not less complicated than those of the unfeathered skin. The skin of the occipital region covered with relatively long feathers possessed circularly arranged, dense vascular networks around the feather follicles. Therefore, the head may be considered, as a whole, to pup on a cap of well developed capillary networks.
2. The subepidermal capillary networks of the comb and the wattle proved to be composed of typical sinusoidal capillaries, whereas those of the remainder regions were formed by complicated and markedly sinuated capillaries. The complication and density of vascular networks seemed to be in relation with the largeness and distributional density of the feathers covering the skin.
3. Those well developed vascular networks located just beneath the epidermis strongly pointed to the possibility of the direct loss of body heat through the skin. Thus the head region seems to play an important role in the thermal regulation of the chicken body.