The integumentary system includes the epidermis and dermis. Below those two layers is the subcutaneous layer, which is not part of the integument.

The epidermis is keratinized, stratified squamous epithelium; it's thickness ranges from 0.o75 to .6 mm.

The dermis is made up of connective tissue proper. It mostly contains collagen fibers along with elastic and reticular fibers in smaller amounts. Two major regions are found with in the dermi: superficial papillary layer and deeper reticular layer.

There are six layers: stratum corneum, superficial layer for barrier function; stratum lucidum, only on thick skin; stratum granulosum, where keratinization starts; stratum spinosum, composed of desmosomes from structural support and epidermal dendritic cells for immune support; and the stratum basale, basement layer of keratinocytes, melanocytes, and tactile cells.

O'Loughlin, V. D., Bidle, T. S., & Mickinley, M. P. (2022). Anatomy and Physiology. McGraw Hill. https://prod.reader-ui.prod.mheducation.com/epub/sn_c06d4/data-uuid-8abe49b017a345a89cb7084865b2cb03

(page 186-191, section 1)