A large network of interconnected signaling pathways in human ovarian follicles is supported by the gene expression activity of the granulosa cells.

Human follicular fluid (hFF), as an extra oocyte microenvironment, is essential to the biological processes of oocyte development. Using liquid chromatography-tandem mass spectrometry (LC-MS/MS), we identified 426 proteins as consistently present in hFF from different participants. According to our gene chip data, the granulosa cells in the follicle locally produce 235 of these proteins. These data suggest that the granulosa cells actively participate in the follicular development by synthesizing important molecules to support the activity of pathways that are essential to oocyte development and genomic preservation. The computational Ingenuity Pathway Analysis (IPA) suggests that the identified proteins have well-established functions in the pathways of steroidogenesis, cell-to-cell signaling and interaction, molecular transport, the antioxidative system, interleukin 1 (IL-1) and IL-6 signaling, liver X receptor/retinoid X receptor (LXR/RXR) activation, and the interconnective insulin-like growth factor and lipid metabolism networks. The hFF peptide composition is likely to serve not only the inflammatory follicular state as has been previously suggested; rather, it is a highly diverse and multifunctional environment with several interconnected pathways. These results provide us with important knowledge related to the environment in which the oocyte develops as well as the molecular basis for controlling the process independently of blood supply.

Mature hair follicles generated from dissociated cells: a universal mechanism of folliculoneogenesis.

The hair follicle is considered to be a model system for studying organogenesis. In our initial study using mouse cells (Zheng et al., 2005) we found that new hair follicle formation always starts from an epithelial platform: the epidermal cells aggregate, the aggregates encyst, and from the periphery of the cysts, centrifugally, hair buds, pegs, and follicles form. In this report, we extend our initial study to four distantly related mammals: opossum, rat, dog and human. We find that in these four species, plus mouse, the most trichogenic cells are found in the earliest stages of hair follicle development and that the cellular mechanism of new hair follicle formation starting from dissociated cells is largely the same. These studies suggest that there is essentially one way by which dissociated mammalian skin cells form a new hair follicle in vivo and that this mechanism has been highly conserved.