Date_TXT

Enfield : Science publ., cop. 2005

Cote

597.35 HAM

Auteur

Hamlett, William C.

Sujet

Phylogénie Rajiformes -- Reproduction (biologie) Chondrichthyens -- Reproduction (biologie) Requins -- Reproduction (biologie)

Type de document

Livre

Description :

Chondrchlhyan fishes successfuls utilize a remarkaby diverse and complex array of reproductive modes, all of which result in the production of a small mumber of relatively large offspring. Internal fertilization and an adaptable reproductive trad, coupled with mechanisms for endocrine regulation, facilitated evolution oviparity and diverse viviparous strategies. Since chondrichthyaris are anamniotes, the morphological and physiological mechanisms recruited for specific reproductive modes involve the volk sat and uterine specializalions and not an amnion, chorion or allanlois. Reproduclion is either total reliant on volK stores as let ithotrophy or the mother augments yolk stores, via a variety ol mecahanisms, as malrotrophy Internal fertilization is universal in chondrichlhyan fishes and, as such, requires a suite ol biological activities, including behavioral, morphologic al and plysiologkac mechanisms, to ensure successful copulation and fertilization. This volume correlates available data and ideas concerning the development, reproductive morphology. function and phvlogeny of chondriththyan fishes. The information presented and discussed is fundamental to our understanding ol oogenesis, spermatogenesis, gestation, regulation of repiodiutive gract function, sperm storage, nutrient provision, placentalion, phylogens and are pertinent to out concepts of the origin of live bearing in general. new and exciting data is presented including the idea that yolk sat viviparity is the plesiomorphic slade rather than oviparity.