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The Science Bulletin of the Faculty of Agriculture. University of the Ryukyus >
No.34 (1987/12) >

Title :矮小硬殻卵の連続産出鶏における解剖的観察(畜産学科)
Title alternative :Anatomical Observations in Hens which Had Continously Laid the Hard-Shelled Dwarf Eggs (Department of Animal Science)
Authors :仲田, 正
古謝, 瑞幸
Authors alternative :Nakada, Tadashi
Koja, Zuiko
Issue Date :5-Dec-1987
Abstract :産卵鶏において卵内に卵白片あるいは卵黄小片を有する矮小硬殻卵を連続的に産出する事例が観察された。今回,その産出原因を究明するため同産出鶏32羽を屠殺し,剖検した。また,産出された136個の矮小硬殻卵について,形状並びにその核成分について調べた。剖検によると,腹腔内は排卵卵子から漏出した卵黄液で満たされ,漏出後の卵黄膜の数は産出された矮小硬殼卵の数と一致することから,連続的な矮小硬殼卵の産出は排卵と密接に関連した事象であることが推察された。生殖器官のうち卵巣は全例共正常であったが,逆に卵管は全例に形態的異常を認めた。すなわち,卵管膨大部前部の卵管壁においては腫瘍や瘢痕組織が観察され,卵管漏斗部の卵管靱帯には水腫の付着が認められた。腫瘍並びに瘢痕組織の存在する部位は極めて厚く,硬化しており,卵管腔が狭くなっていた。水腫はいずれの事例でも排卵直前には卵管へ取り込まれ,卵管口を封鎖していた。これら卵管における異常性によって,排卵卵子は卵管全長を通過することができず,卵形成の核にもなり得ず,その代り取り込みなどの刺激によって形成された卵白が核になったものと思われた。矮小硬殻卵の殆どが長球状を呈し,一部は円柱状であった。核成分は,長球状のものでは殆どが球状の卵黄小片であったのに対し,円柱状では細長い糸状の卵白であった。このことから核のサイズが卵の大きさに,核の形状が卵の形状に関連すると思われた。
The shape and contents of the hard-shelled dwarf eggs of Single White Leghorn were examined. Autopsy was performed on 32 hens which had continously laid the hard-shelled dwarf eggs to observe the state of their reproductive organs. There were two distinct types of the dwarf eggs with respect to their shape : The prolate-spheroidal type, similar to a normal egg; and the cylindrical type, much longer in proportion to the breadth. These dwarf eggs contained a small yolk or no yolk but the nucleus around which albumen was formed in various forms. Autopsy revealed that in all hens the body cavities contained a yellow fluid which was chiefly yolk which had escaped from the vitelline membrane of the ovum ovulated. The number of the partially ruptured vitelline membrane was the same to that of the hard-shelled dwarf eggs produced. The production of the dwarf egg was closely associated with ovulation. In case of the oviduct of these hens, the anterior portion of magnum and the oviducal ligament in the region of infundibulum were obiously abnormalities. Thick and hard tumorous or scar tissue at the oviducal wall of magnum constricted the lumen of the oviduct and prevented the passage of a normal egg, but allowed the passage of a small piece of yolk or a fragment of albumen. At the time of autopsy it was observed that a large cyst at the oviducal ligament had been engulfed by infundibulum. It seemed therefore that a large cyst directly blocked the entrance of a normal yolk by closing the mouth of the oviduct. From these autopsy records, it was assumed that the yolk which had entered the oviduct was unable to pass the obstructive portion and a large fragmental yolk or entire yolk was expelled into the body cavity. In this case, a part of yolk picked up by the oviduct would have become a nucleus for the formation of the egg envelopes. As the result, the hard-shelled dwarf egg with a small yolk was laid. On the other hand, when the mechanical stimulation to the albumen secreting region of the yolk before breaking or cyst prior to their expulsion from the oviduct into the body cavity was synchronized with ovulation, the secretion activity for the egg formation in the oviduct was significantly activated. When the oviduct was in such a specific state, the complete set of egg envelopes was stimulated by the small lumps of hardened albumen, which in these cases seemed to be the nucleus of the dwarf egg. As the result of this, the hard-shelled dwarf eggs without yolk would have been produced.
Type Local :紀要論文
ISSN :0370-4246
Publisher :琉球大学農学部
URI :http://hdl.handle.net/20.500.12000/3907
Citation :琉球大学農学部学術報告 = The Science Bulletin of the Faculty of Agriculture. University of the Ryukyus no.34 p.29 -35
Appears in Collections:No.34 (1987/12)

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