GLOSSARY 



Many of the following terms were used for the first time within the last decade. The definitions are 

 derived from numerous current writings of Experimental Embryologlsts and the author has attempted to incor- 

 porate the various shades of meaning Into succinct statements. 



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ABORTION - termination of pregnancy at a non-viable stage of the foetus. 



ACHONDEOPLASTIC - refers to miniature adult skeletal condition of some midgets. 



ACIDOPHIL - oxiphll; cell constituents stained with acid dyes, often used to designate an entire cell type. 



(See basophil) 

 ACTION, DYNAMIC - Weiss' variation 6f t;he field theory or concept. 

 ACTIVATION - stimulation of spermatozoon to accelerated activity, generally by chemical means (e.g., fer- 



tllizin); process of initiating development in the egg; the liberation of naturally occurring evocators 



from an inactive combination. 

 ACTIVATION CENTER - one of the two organization centers in the insect egg. 

 ACTIVITY, FUNCTIONAL - stimulation or inhibition of a developing organ by environmental variables (e.g., 



hypertrophy of the urodele gills in an oxygen deficient medium). 

 ADAPTATION - functional and correlative change, however brought about. 



ADAPTATION, FUNCTIONAL - an organ will adapt itself structurally to an alteration, qualitative or quantita- 

 tive, of function (Boux). 

 ADNEXA - extra embryonic structures discarded before the adult condition is attained. 

 AESTIVATION - reduced activity during the summer period by some animals, term opposed to hibernation. 

 AFFINITAT - tendency to contact; may be positive, resulting in maximal contact or may be negative, resulting 



in minimal contact (Holtfreter, 1939) • Not thigmotaxis. 

 AFFINITAT, INTERFAZIALE - tendency to contact between marginal surfaces or interfaces of different blaa- 



tomeres ( Lehmann) . 

 AFFINITAT, INTEABLASTEMATISCHE - tendency to contact between cells of the same blastema (Lehmann). 

 AFFINITY - tendency of cells and tissues of the early embryo to cling together when removed from their normal 



environment. Equivalent to the cytarme of Boux. 

 AGENESIS - developmental failure of a primordium (e.g., absence of arm or kidney). 

 AGGLUTINATION - cluster formation; a spontaneously reversible reaction of spermatozoa to the fertllizin of 



egg-water. 

 AGGREGATION - coming together of cells (e.g., spermatozoa) without sticking, a non-reversible response com- 

 parable to chemotropism. 

 AGNATHUS - absence of lower Jaw. 



AKINETIC - without a kinetochores (e.g., in a chromosome). 

 ALIMENTAHY CASTBATION - prolonged starvation (Adams, 1930). 

 ALLANTOIN - nitrogenous portion of allantoic fluid. 

 ALLAKTOIS - an extra embryonic sac-like extension of the hindgut of amniotes, having the dual function of 



excretion and respiration. 

 ALLO-HAPLOID - androgenetio haploid. 

 ALLOMETRY - study of the relative sizes of parts of animals at different absolute sizes, ages, weights, or 



chemical compositions. Term now used in place of heterogony by Huxley and Teissier (1956). 

 ALLOMOEPHOSIS - the physical or chemical relation of parts of an organism at some early stage to either 



the whole or part of a later stage, (e.g., the egg size compared with the adult size or weight). 

 ALLOPHORES - red pigment in solution. 

 ALLO- POLYPLOID - polyploid species hybrid. 

 AMBOCEPTOR - a synonym used for fertillzln in suggesting its double combination with the sperm and egg 



receptors in the process of fertilization. This double receptor may also receive blood inhibitors, 



or antl -fertllizin. 

 AMELUS - failure of the extremities to develop, remaining as mere stubs. 

 AMNION - thin, double membrane enclosing the embryos of some invertebrates and of reptiles, birds, and 



mammals. It Is derived from the somatopleure in vertebrates. 

 AMiilOTIC BANDS - fibrous bands from the amnion to the embryo due to local necrosis of foetal tissues. 

 AMNIOTIC RAPHE - point of Junction of the amniotic folds as they encircle the embryo, synonymous with 



sero-amniotic or chorio-amniotic Junction. 

 AMPHIBLASTIC - complete but unequal segmentation in teloleclthal eggs. 

 AMPHITOKY - parthenogenetic reproduction of both males and females. 

 AMPLEXUS - the sexual embrace of female ty the male amphibian. This may or may not occur at the time of 



ovi position. 

 AMPHOTEROKY - production of both sexes in a- single parthenogenetic brood. 

 ANALOGOUS - structures said to have the same function but different embryologloal and/or evolutionary 



origin. Opposed to homologous. 

 ANDBOGAMONES - the antl-fertllizins of Llllle, so named Ijy Hartmann. An acidic protein of low molecular 



weight. 

 ANDBOGENESIS - development of the egg with paternal (sperm) chronosomes only, accomplished by removing the 



egg nucleus after activation by the spermatozoon but before syngany (Wilson, 1925). May also be 



accomplished by irradiation damage of egg nucleus. 



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