INTRODUCTION TO DEVELOPMENTAL

BIOLOGY BY

VENNILA.J

WHAT IS DEVELOPMENT?

HISTORY OF DB• DESCRIPITIVE AND COMPARATIVE EMBRYOLOGY• EXPERIMENTAL EMBRYOLOGY• ANALYTICAL EMBRYOLOGY MORGAN T.H. -1919

HISTORICAL REVIEW• CELL THEORY

FIRST WESTERN PHILOSOPHER• ANAXIMANDER -600B.C.

GREEK PHILOSOPHER• EMPEDOCLES

FATHER OF ZOOLOGY• ARISTOTLE (384-322B.C.) • THE TREATISE ON EMBRYOLOGY -book

William Harvey and Marcello Malpighi

PREFORMATION THEORIES• DUTCH SCIENTIST-SWAMMERDAM• HOMUNCULUS

HARTSOEKER

EPIGENETIC THEORY• CASPER FRIEDRICH WOLF –SIMPLER FORM TO MORE COMPLEX

ORGANISATION.

• JOHAN FRIEDRICH HAECKEL SUPPORTED

BAER’S LAW• FATHER OF MODERN EMBRYOLOGY • STATES more general features

common develop earlier than special features which distinguish various members of the group.

RECAPITULATION THEORY• MULLER AND HAECKEL BAER’S TO RECAPITULATION • ONTOGENY RECAPITULATION PHYLOGENY

BIOGENETIC LAW • MODERN VERSION OF RECAPITULATION

WEISMANN’S THEORY OF GERMPLASM

GERMPLASM THEORY LANDMARK OF DB

MOSAIC THEORY • WILHELUM ROUX • ONTOGENIC DEVELOP –DIFF CELL FROM A >/< UNDIFF EGGTO

GREATER DIFF AND SPECIALISA OF CELL.

REGULATIVE THEORY• HANS DRIESCH OPPOSED MOSAIC THEORY GRADIENT THEORY • BOVERI SPEMANN’S THEORY OF ORGANISERS • SPEMANN