Table 1. Spectrum of limb malformations observed following treatment of chick limb buds with cyclopamine.

The chick wing has 3 digits, denoted digits II-III-IV from anterior to posterior, while the chick leg has 4 digits, denoted digits I-II-III-IV. Cyclopamine was added at a range of embryonic stages as indicated. The number of embryos exhibiting a given phenotype is represented relative to the total number of embryos treated at the same stage.

Stage treatment	Number affected	Phenotype
Wing (II-III-IV)
S18	2/7	Severely disorganized elements. Shortened humerus, loss of ulna, single fused carpus, 2 digits each with a single phalange
	5/7	Digit IV loss
S20	10/14	Digit IV loss
	4/14	Digit IV reduction
S22/23	10/11	Digit IV reduction
	1/11	Morphologically normal digits
S24	9/10	Morphologically normal digits
Leg (I-II-III-IV)
S18	4/7	Loss of fibular and digit IV loss, digits I-II-III each have 2 phalanges.
	3/7	Digit IV reduction
S20	4/14	Digit IV loss, digit III reduction
	6/14	Digit IV loss
	4/14	Reduction and fusion of digits III and IV into a single phalange
S22/23	4/17	Digit IV reduction
	6/17	Reduction and fusion of digits III and IV into a single phalange
	1/17	Digit IV loss with digit III reduction
	1/17	Digit IV loss
	5/17	Morphologically normal digits