Embryology of Dolphins: Staging and Ageing of Embryos and Fetuses of Some Cetaceans

ISBN-13: 9783540672128 / Angielski / Miękka / 2000 / 133 str.

Milan Klima; Oldrich Sterba; Bernd Schildger

Opis

The study of intrauterine development and growth while consistently respecting the time factor enabled the authors to determine the time course of organogenesis of all organ systems. The resulting comparison with other mammals detected the time lag in ossification, retardation of odontogeny, the time of the origin and development of the fluke, dorsal fin and flipper, etc. The authors believe the Staging and Ageing Method serves for much more efficient evaluation of existing embryological collections which very often contain embryos of unknown age.

Spis treści

Introduction.-Length and weight of adults, life span.-Length and weight of newborn, ontogenetic patter.-Duration of intrauterine development.-Mating and calving seasons.-Calving intervals, duration of lactation.-Aims of this study.-Material.-Methods.-Staging.-Ageing.-Results.- Developmental stages in the dolphin species under study.-Development of body shape and fetal growth.-Development of head shape and its growth.-Development of thoracic limb (flipper).-Development of pelvic limb buds.- Development of the fluke.-Development of the dorsal fin.-Duration of intrauterine development.-Mating and Calving Seasons.-Discussion.- Comparison of the staging and ageing method with other methods.-Duration of intrauterine development and the mating and calving seasons.-References.-Index

Blurb

Comparative embryology has been neglected in the past decades. In our opinion the decreased interest has been caused by the fact that the time factor has not suffficiently been respected. Therefore we used the Stageing and Ageing Method (Sterba 1995) to determine the ontogenetic age of embryos and to state the time tables and time relations of various ontogenetic events. We examined 167 embryos and fetuses of four dolphin species (collection Dr. Senckenbergische Anatomie, Franfurt am Main). The study of intrauterine development and growth while consistently respecting the time factor enabled us to determine the time course of organogenesis of all organ systems. The resulting comparison with other mammals detected the time lag in ossification, retardation of odontogeny, the time of the origin and development of the fluke, dorsal fin and flipper, etc. We believe the Stageing and Ageing Method serves for a much more efficient evaluation of existing embryological collections which very often contain embryos of unknown age.