VL GLOSS ARy Of TERMS IH EXPERIMENTAL EMBRYOLOGY 



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 Embryologists and the author has attempted 

 to incorporate the various shades of meaning into succinct statements. 



ABORTION - termination of pregnancy at a 

 non-viable stage of the foetus. 



ACHONDROPLASTIC - refers to miniature 

 adult skeletal condition of some midgets. 



ACIDOPHIL - oxiphil; cell constituents stained 

 with acid dyes, often used to designate an 

 entire cell type. (See basophil) 



ACTION, DYNAMIC - Weiss' variation of the 

 field theory or concept. 



ACTIVATION - stimulation of spermatozoon to 

 accelerated activity, generally by chemical 

 means (e. g. , fertilizin); process of initi- 

 ating development in the egg; the liberation 

 of naturally occurring evocators from an 

 inactive combination. 



ACTIVATION CENTER - one of the two organ- 

 ization centers in the insect egg. 



ACTIVITY. FUNCTIONAL - stimulation or in- 

 hibition of a developing organ by environ- 

 mental variables {e. g. , hypertrophy of the 

 urodele gills in an oxygen deficient mediunn). 



ADAPTATION - functional and correlative 

 change, however brought about. 



ADAPTATION, FUNCTIONAL - an organ will 

 adapt itself structurally to an alteration, 

 qualitative or quantitative, of function 

 (Roux). 



ADNEXA - extra embryonic structures dis- 

 carded 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 pos- 

 itive, resulting in n:iaximal contact or may 

 be negative, resulting in miniinal contact 

 (Holtfreter, 1939). Not thigmotaxis. 



AFFINITAT, INTERFAZIALE - tendency to 

 contact between marginal surfaces or in- 

 terfaces of different blastomeres (Lehmann). 



AFFINITAT, INTRABLASTEMATISCHE - tend- 

 ency to contact between cells of the same 

 blastema (Lehmann). 



AFFINITY - tendency of cells and tissues of the 

 early embryo to cling together when re- 

 moved from their normal environment. 

 Equivalent to the cytarme of Roux. 



AGENESIS - developmental failure of a pri- 



mordium (e. g. , absence of arm or kidney). 



AGGLUTINATION - cluster formation; a spon- 

 taneously reversible reaction of sperma- 

 tozoa to the fertilizin of egg-water. 



AGGREGATION - coming together of cells (e. g. 

 spermatozoa) without sticking, a non-re- 

 versible response comparable to chemo- 

 tropism. 



AGNATHUS - absence of lower jaw. 



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

 chromosome). 



ALIMENTARY CASTRATION - prolonged star- 

 vation (Adams, 1930). 



ALLANTOIN - nitrogenous portion of allantoic 

 fluid. 



ALLANTOIS - an extra embryonic sac-like ex- 

 tension of the hindgut of amniotes, having 

 the dual function of excretion and respira- 

 tion. 



ALLO-HAPLOID - androgenetic 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 (1936). 



ALLOMORPHOSIS - 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 fertilizin 

 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 anti-fer- 

 tilizin. 



AMELUS - failure of the extremities to develop, 

 remaining as mere stubs. 



AMNION - thin, double membrane enclosing the 

 embryos of some invertebrates and of rep- 

 tiles, birds, and mammals. It is derived 

 from the somatopleure in vertebrates. 



AMNIOTIC 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 seg- 

 mentation in telolecithal eggs. 



AMPHITOKY - parthenogenetic reproduction of 

 both males and females. 



* Glossaries of terms in nonnal embryology may be found in Hugh's "The Frog! Its Reproduction and Development" {McGraw-Hill, N. Y. ) and in 

 his "Laboratory Manual of Vertebrate Embryology" (Burgess 1961) 



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