
Classification of some candidate materials inhibiting embryogenesis 
Analogues act with one or several definite chemical components 
of the cell. 
Due to their close resemblance structurally to 
vitamins (metabolic intermediaries) they interfere specifically 
with the proper function of the corresponding natural substances 
Purine analogues 
Seazaquanine (Waddington, 1955) 
azahypoxamine y 
benzimidazole 
Steroids 

cortisone (Sobel, 1958) 
sex hormones (sunthetic and extracted) 
testosterone propionate 
Leazaserine Sebi Cg et te AER ta diethylstilbesterol (van Tienhoven 
quanazole (Younger et al.,1950 
Amino acid analogues 
ethionine (Feldman & Waddington, 1955) 
A -HH5-8 - chloro-valeric acid( 
DL=- w= bromoallylglycerine ( 
1957) 
Goitrogens 
Thiourea (Sinha, 1959) 
Tiouracil  " 
Thyroxine (Beyer, 1952) 
A e-«NH- 8 -chloro-butyric acid(.Herrman, 
B= 2 = thienylalanine 
para-chlorophenylalanine ( 
ortho-chlorophenylalanine ( 
W #jpromoallylglycine ( 
A w»bromoallylglycine ( 
propargyl glycine (-(Herrman, 
ey clopentaneglycine ( 1955) 
DL-bromopropionylalanine ( 
Aliphatic acid analogues 
Aromatic acid analogues iP ceay 
( 
( 
1954) 
8B -2-thienylalanine 
p-0-chloro-phenylalanine 
Other analogues 
benzimidazoles 
2-ethyl-5«methylbenzimidozole 
2-hepta-5emethylbenzimidozole 
2-ethyl-5-methylbenzimidozole 
(also inhibits. biosynthetic 
processes involving nucleic 
acid or nucleoprotein build-up) 
1953) 
( 
| 
poheteckweas & Shorb, 1958) 
( 
( 
Inhibitors of Tissue Differentiation 
Diazo dyes (Wilson, 1955;Beaudoin, 1961) 
Trypan Blue * 
Evans Blue 
Niagara Blue 4B " 
Mitotic Interference 

- 1960,61) 
triethanomelamine TEM (Jurand,1958,59, 
fluro~acetyl derivative of :. 
N=-(p-amino=phenyl)-nitrogen mustard " 
Hatchability Suppressor 
Sterculia-foetida oil ( suspected 
Crude cottonseed oil ( reactive 
cyclopropane 
fatty acids 
41 
