title: Expansion of specialized epidermis induced by hormonal state and mechanical strain.
abstract: In mammals, some sites of specialized skin such as the palms, soles, and lips grow proportionally with the animal. However, other types of specialized skin such as the nipple and anal/genital region are dramatically altered with changes of reproductive status. The specific cell types that mediate the growth of these sites have not been identified. In the mouse, we observed a dramatic expansion of the specialized epidermis of the nipple, coupled to changes in connective tissue and hair shaft density, which we designate as areola formation. During this process thymidine analog uptake was elevated in the epidermis and hair follicles. Although there were no changes in connective tissue cell proliferation, we did observe an altered expression of extracellular matrix genes. In addition, the fibroblasts of the virgin nipple areola and region showed increased transcript and protein levels for estrogen, progesterone, relaxin, and oxytocin relative to those of ventral skin. To determine the role of pregnancy, lactation hormonal milieu, and localized mechanical strain on areola formation, we created models that separated these stimuli and evaluated changes in gross structure, proliferation and protein expression. While modest increases of epidermal proliferation and remodeling of connective tissue occurred as a result of individual stimuli, areola formation required exposure to pregnancy hormones, as well as mechanical strain.
authors: Medical Sciences, Indiana University School of Medicine, Bloomington, IN 47405, USA.
authors: Hsin-Jung
authors: HJ
authors: Wu
authors: Medical Sciences, Indiana University School of Medicine, Bloomington, IN 47405, USA.
authors: Teresa
authors: T
authors: Easwaran
authors: Medical Sciences, Indiana University School of Medicine, Bloomington, IN 47405, USA.
authors: Carlos D
authors: CD
authors: Offutt
authors: Medical Sciences, Indiana University School of Medicine, Bloomington, IN 47405, USA.
authors: Richard Levi
authors: RL
authors: Elgar
authors: Department of Dermatology, Indiana University School of Medicine, Indianapolis, IN 46202, USA.
authors: Dan F
authors: DF
authors: Spandau
authors: Medical Sciences, Indiana University School of Medicine, Bloomington, IN 47405, USA.
authors: Sachiko
authors: S
authors: Koyama
authors: Medical Sciences, Indiana University School of Medicine, Bloomington, IN 47405, USA; Department of Dermatology, Indiana University School of Medicine, Indianapolis, IN 46202, USA. Electronic address: jgfoley@indiana.edu.
authors: John
authors: J
authors: Foley
mesh_terms: D000818:Animals; D004817:Epidermis / Q000502:physiology*; D005109:Extracellular Matrix / Q000235:genetics / Q000378:metabolism*; D005260:Female; D007774:Lactation / Q000502:physiology; D051379:Mice; D009558:Nipples / Q000502:physiology*; D011247:Pregnancy; D013314:Stress, Mechanical
keywords: Areola; Hormones; Lactation; Mechanical strain; Nipple; Pregnancy