Titlebook: Seasonal Spermatogenesis in the Mute Swan (Cygnus olor); Haide Breucker Book 1982 The Editor(s) (if applicable) and The Author(s), under e

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Material and Methods,eese the swans make up a subfamily (Anserinae) which, with the ducks and their relatives are again classified as the family of Anatidae. This family, together with that of the game-birds, makes up the order of Anseriformes (Grzimek et al. 1968).

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Topography and Microscopic Anatomy of the Testes of the Swan,caudal to the lungs (Fig. 1), separated by parts of the diagonal and horizontal septum; they are situated in the cranial area of the cavitas peritonealis intestinalis. The testes are each attached medially to the back abdominal wall by a short mesorchium. They lie on either side of the dorsal mesent

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The Complete Process of Spermatogenesis,le to that in other birds and also in mammals, i.e., the succession of the individual germ cell generations inside the seminiferous tubules is spatially ordered. The germinal epithelium is made up of four generations of cells which are arranged in order of their progressive development, from the bas

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The Annual Cycle of the Male Gonads (Light Microscopic Studies),of activity in the female, the production of male germ cells capable of fertilization is also confined only to a short duration of time within a year, usually to the months of April and May in temperate northern latitudes. The preliminaries for the attainment of this goal begin already at the end of

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The Regression Period (Electron Microscopic Studies),characteristics of the different types of germ cells, as far as they can be met out of the active phase of spermatogenesis, do not change, it is not necessary to repeat the description of their ultra-structure. However, when these cells disintegrate, then their density often changes so much that cer

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Book 1982is class is more or less complete. Extensive observations - to a large extent by amateur ornithologists - with respect to geographical distribution, life cycles, demands on and adaptations to the environment, breeding habits, migration, and so forth have contributed towards basic and more widely rel

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