Glossary 675 



Diploblastic — with two germ layers. 



Diploid — having the full complement of chromosomes. 



Distal — away from the point of attachment to the main body mass. 



Dominant — in genetics that member of a pair of factors which, when both are 



present, expresses itself over the other. 

 Dorsal — pertaining to the back of an animal. 

 Duodenum — anterior part of small intestine. 



E 



Echinodermata — phylum of anin^als that contains the starfish and related forms. 



Ectoderm — the outer germ layer of the embryo. 



Effector — an organ that makes a response. 



Efferent — conducting away from a specific structure or organ. 



Embolus — a foreign particle or clot circulating in the blood. 



Embryo — an organism in an early developmental stage. 



Endocrine gland — a gland that secretes its products directly into the blood 



stream for distribution to all parts of the body. 

 Endoskeleton — an internal skeleton. 



Endothelium — an epithelium which lines internal cavities of the body. 

 Entoderm — the inner germ layer of the embryo. 

 Enzyme — organic catalyst that brings about reactions without appearing in the 



final products. 

 Epicondyle — a bony ridge above the condyle. 

 Epidermis — outer layer of the skin. 

 Epiglottis — a flap of tissue above the glottis. 

 Epithelium — a type of connective tissue that covers a surface. 

 Epiphysis — the end region of a long bone. 

 Erythrocyte — a red blood cell. 

 Esophagus— upper part of the digestive tract ; it leads from the posterior portion 



of the mouth to the stomach. 

 Estrus — mating period of most mammals when the female is receptive to the male. 

 Evolution — the gradual developnient of new forms. 

 Exoskeleton — an external skeleton. 



Family — in classification, a category more inclusive than the genus and less than 



the order. 

 Fascia — a sheet of connective tissue that separates muscle layers. 

 Fascicle — a bundle. 



Fat — one of the basic food substances ; a type of connective tissue. 

 Feces — waste materials expelled from the large intestine. 

 Fertilization — the union of the male and female gametes. 

 Fetus — in mammals, the young in the later stages of intrauterine development. 

 Fibrin — an insoluble, fibrous protein formed from fibrinogen during blood clotting. 

 Fibrinogen — a soluble protein present in the blood. 

 Fission — division. 



