The hair follicle is a dynamic mini-organ which undergoes phases of periodic cycling. It consists of mainly epithelial cells with a small population of mesenchymal cells. Mesenchymal-epithelial signalling drives hair follicle morphogenesis and postnatally similar mesenchymal-epithelial signalling is recapitulated to produce new hair at the start of a new hair cycle. Regeneration of a hair follicle is mainly attributed to inductive signals from the dermal papilla, which are specialised mesenchymal cells found at the base of the hair follicle. Dysregulation of the hair cycle can lead to hair disorders such as androgenetic alopecia in which terminal follicles miniaturise into vellus follicles as a result of aberrant signalling in response to androgens. The hair follicle cycling, and growth is also influenced by the macroenvironment surrounding the follicle. In the first section of this thesis, the macroenvironment of hair follicles in androgenetic alopecia is investigated through whole-mount immunolabelling and volumetric imaging. I found that follicles have reduced innervation and blood vessels but there is an increase in lymphatic vessels in androgenetic alopecia. I observed network of nerves and blood vessels connecting hair follicles in a follicular unit pointing towards a follicular unit macroenvironmental regulation of hair growth. The next part of the thesis investigated the role of the dermal papilla in miniaturisation of hair follicles. Assessing the ability of frontal and occipital dermal papilla cells using an in vitro double spheres model revealed decreased ability of frontal dermal papilla cells to differentiate bulge cells into follicular keratinocytes. Transcriptional profiling of patient-matched intact frontal and occipital dermal papilla and dermal sheath showed inherent differential gene expression between frontal and occipital dermal papilla and dermal sheath with each cell type defined by expression of unique signature genes. Occipital dermal papilla signature contained genes that maintain dermal papilla identity, but also novel genes were identified, whose roles in the hair follicle have not been defined. TRPS1 was selected as the gene of interest as it has been shown to have a role in both hypotrichosis and hypertrichosis implicating it in control of follicle size. The data suggests that TRPS1 potentially is involved in the maintenance of dermal papilla identity, while its expression is required for bulge cell activation to promote a new growth phase. Regulation of TRPS1 expression by the androgen receptor further supports the role of TRPS1 in providing protection against miniaturisation of occipital hair follicles.