On the development of the papillary body in the feline claw

The pre- and post-natal development of the feline claw was studied in 22 feline fetuses with a crown-rump length (CRL) ranging from 40 to 160 mm, in six kittens up to an age of 22 days, and in four adult cats. In fetuses up to a CRL of 75 mm, the characteristic shape of the feline claw was developed. Segment-specific dermal modifications in the various segments, especially the dorsal ridge, started to develop in fetuses with a CRL between 75 and 105 mm. Modifications of the papillary body in the different claw segments took place in the last third of prenatal development and were continued postnatally. At first, the basal lamina became wavy, followed by the formation of small dermal microridges, which would be enlarged to dermal ridges and lamellae. In the claw of adult cats, the papillary body was very small. The dermal tissue of the proximal part of the coronet formed low microridges with short papillae originating on and between these low ridges. In the wall segment, dermal microridges were formed which were arranged in a parallel fashion, and in the distal part of the wall, short dermal micropapillae arose on the crest of each microridge. In the sole segment, thin dermal lamellae were developed. The sequence of papillary body development and the varying conformations of the papillary body in the different segments of the feline claw are compared to those in the nail, the canine claw and hooves.