The Development of the Integumentary System in Dogs

The skin and its appendages are components of the integumentary system. Particularly in dogs, the appendages are: the hair, claws, footpads, and sebaceous, sweat and mammary glands. Few studies report the initial development of these structures in domestic species. The present study aimed to describe the development of the integumentary system during the embryonic and fetal periods in dogs (Canis familiaris). Totally, 9 embryos and 31 fetuses were used for gross and microscopic descriptions. Macroscopically, the skin of concepts in embryonic ages had a translucent aspect, which allowed for the visualization of internal organs with a remarkable presence of blood vessels. The skin appendages were only identified in fetuses. Microscopically, in the embryonic period, the epidermis consisted of a single surface layer of flattened cells denoted the germinativum stratum or germinal layer. Later, a new layer form due the proliferation of keratinocytes to form the periderm. When the epidermis of the fetus was observed. There was more than one cell layer that developed between the germinal and periderm layers. In conclusion, the skin shows little development during the embryonic period, whereas its division into the dermis and epidermis and the formation of several cell layers is pronounced in the fetal period. Similarly, skin appendages developed during the fetal period