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Of all the classes in the animal kingdom, birds represent the best
known. There are in total about 8600 living species, and the
systematic study of this 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 relevant
knowledge, e. g., in the areas of ethology, ecology, and evo lution
and also in social biology (Hilprecht 1970; Farner and King 1971).
Together, all these aspects are affected by the reproductive
biology of birds, and studies have therefore been carried out for
many years with special emphasis on this subject. How ever, until
now this emphasis in avian reproductive biology has been
physiological and in particular endocrinological (Murton and
Westwood 1977; Roosen-Runge 1977). The morphology of the gonads has
been treated in far less detail, and has been confined to a
comparatively small number of species, compared with other classes
of vertebrates. Reproduction is the section in the life cycle of an
animal which is most dependent upon environmental conditions.
Reproduction therefore usually takes place at a par ticular time,
when stress for the adult animals is at its lowest and the chances
of sur vival for the newborn are at their highest, i. e."
Einem neuen Konzept folgend, schildert die "Human- embryologie" die
gesamte Ontogenese des Menschen, ausgehend von allgemeinen
entwicklungsbiologischen Fragen }ber pr{- natale Diagnostik bis hin
zur Problematik des Schwanger- schaftsabbruchs. Das Buch enth{lt
sehr umfangreiches Bild- material, das ich }berwiegend auf
menchliche Embryonen st}tzt.
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