Structure of the Pilosebaceous Gland

All sebaceous glands are similar in structure. They consist of either a single lobule (acinus) or a collection of acini. The glands are separated from the dermis by a connective tissue capsule, consisting of fine collagen fibers, fibroblasts, and a capillary plexus. The ultrastructure of human sebaceous cells does not vary significantly from one skin site to another nor does the ultrastructure of sebocytes of prepubertal children differ significantly from that of adults, implying that increased...

Cell Biology of the Pilosebaceous Unit

Follicular Duct

Department of Research and Development, Nu Skin Enterprises, Provo, Utah, U.S.A. This chapter reviews the structure and function of the pilosebaceous unit and the controlling influences on the pilosebaceous unit and sebum secretion. The chapter is divided into three sections. Section I gives an account of the structure and function of the normal pilosebaceous unit Section II describes the biochemistry and regulation of pilosebaceous unit biology and finally, Section III deals briefly with the...

Structure of the Pilosebaceous Duct

Cornification Pilosebaceous Duct

The pilosebaceous duct is lined by a stratified, squamous epithelium consisting of keratinocytes. The duct lumen is frequently colonized by bacteria that rely on the keratinocytes and sebum as a source of nutrients. Several distinct anatomical parts of the duct can be recognized. The opening of the duct onto the surface of the skin is the orifice or ostium. The sebaceous follicles on the back frequently group together and emerge through one orifice (25), while those on the face and chest show...

Sebum Secretion and Acne

Dows Institute, University of Iowa, Iowa City, Iowa, U.S.A. Sebum is synthesized in sebaceous glands, which are part of the pilosebaceous units of the skin (1). Sebaceous glands are epidermal appendages found in all regions of the skin, except the palmar and plantar surfaces however, the greatest density of glands is found in the scalp and facial areas. As sebocytes move from the basal layer at the periphery of the gland toward the lumen, they synthesize neutral lipids, which accumulate as...

Regulation of Pilosebaceous Unit Activity

Pilosebaceous Unit

There are many controlling influences on the pilosebaceous unit (Fig. 3). The development of model systems for the sebaceous gland and duct has made it easier to study these pathways in vitro. Perhaps the most profound and well-known effect of hormones on the pilosebaceous unit is the one caused by androgens, more specifically in causing sebaceous gland enlargement, sebocyte proliferation, and lipid metabolism (91,92). It is well established that the increase in lipid production and enlargement...

Disorders Affecting Pilosebaceous Unit Biology

Various disorders affect pilosebaceous units, although these diseases are rarely life threatening. Three types of skin cysts exist epidermoid cysts result from squamous metaplasia of a damaged sebaceous gland, while trichilemmal cysts and steatocys-toma are both genetically determined structural aberrations of the pilosebaceous duct. Accumulation of material in the follicular lumen results in distension of the follicle, leading to the formation of noninflamed lesions that are typical of acne,...