HISTOGENESIS OF THE CUTANEOUS ENCLOSURE OF THE AURICLE OF THE EXTERNAL EAR IN DOGS

The histomorphological changes occuring in the foetal skin covering the auricle of the external ear of dog (Egyptian-land race) ranging from 70 to 260 mm CVR length were studied.
In foetuses of 70-80 mm CVR length, the epidermis was composed of stratified epithelium covered by periderm. The periderm was replaced by layers of stratum corneum in foetuses of 150 mm CVR length.
The analgen of hair follicles appeared in foetuses of 70-80 mm CVR length. These follicles increased in size and depth with the advancement of age. In foetuses of 150 mm CVR length, the hair follicles could be differentiated into primary central follicles and primary lateral follicles. The primordium of the tubular glands could be also seen at this stage. However, the primordia of sebaceous glands were demonstrated in foetuses of 170 mm CVR length. At 220-260 mm CVR length, the tubular glands were differentiated into a duct and an end-piece. The sebaceous glands were designed into a collection of cells on one or both sides of the central primary follicles and showed signs of activitiy.