Radiata is an extensive artificial group of invertebrates. The members are distinguished by having all the parts arranged radially round the vertical axis of the body, and the various organs repeated symmetrically in each ray or spheromere. Research Radiata
Baron Georges Leopold Chretien Frederic Dagobert Cuvier was a German naturalist. He was born in 1769, at Montbeliard, then belonging to the duchy of Wurtemberg and died in 1832. After studying at Stuttgart he became a private tutor in the family of Count D'Herley, in Normandy, where he was at liberty to devote his leisure to natural science, and in particular to zoology. A natural classification of the Vermes or worms was his first labour. The ability and knowledge shown in this work procured him the friendship of the greatest naturalists of France. He was invited to Paris, established at the Central School there, and received by the Institute as a member of the first class. His lectures on natural history, distinguished not less for the elegance of their style than for profound knowledge and elevated speculation, were attended by all the accomplished society of Paris. In January 1800 he was appointed to the College de France. Under Napoleon, who fully recognized his merits, Cuvier held important offices in the department of public instruction. In 1819 he was received amongst the forty members of the French Academy. Amongst the numerous works by which he greatly extended the study of natural history we may mention Recherches sur les Ossemens Fossiles; Discours sur les Eevolntions de ]a Surface du Globe; Lecons d'Anatomie Comparee; Histoire Naturelle des Poissons; Le Regne Animal, a general view of the animal kingdom, in which all animals were divided into the four great classes: Vertebrata, Mollusca, Articulata and Radiata. Research Georges Cuvier
The acrosome is a thin cap of protoplasm encasing the head of a sperm. The acrosome is believed to contain an enzyme, hyaluronidase, that dissolves the coronaradiata, the protective outer coat of the ovum, making sperm penetration easier. The enzyme of the acrosome of one sperm is insufficient to break down the ovummembrane. Therefore, contrary to popular opinion, it takes more than one spermatozoon to produce a baby. Only one sperm, however, will actually penetrate the egg. Research Acrosome
The corona radiata is a group of follicular cells surrounding the zona pellucida. It is the gelatinous protective outer coat of the ovum. The thin cap surrounding the head of the sperm, called the acrosome, contains the enzyme hyaluronidase, which is capable of dissolving the corona radiata enabling sperm penetration. Research Corona Radiata
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Matt and Leela Probert
Abbreviations
Research Radiata
