Update on Pituitary Folliculo-Stellate Cells

Abstract

Folliculo-stellate cells (FSCs) are a non-endocrine population of sustentacular-like, star-shaped and follicle-forming cells, which contribute about 5-10% of elements from the anterior pituitary lobe. First identified with electron microscopy as non-hormone secreting accessory cells, light microscopy has revealed many of their cytophysiological features, and is known as positive for S-100 protein, a marker for FSCs. They are currently considered as functionally and phenotypically heterogeneous. Secretory cells are in close interconnection with this agranular functional units in an interactive endocrine networking. Due to FSCs communication with their endocrine neighbours, this opens the door to considering the pituitary as a cellular puzzle more ordered than the first thought. After a long period of pituitary research, many issues remain unsolved. In spite of many morphological and cytophysiological studies recently reported, a precise understanding of the major functions of FSCs in the pituitary gland remains unknown. New studies about the origin and differentiation of FSCs are expected to provide many relevant answers with respect to the debate about physiopathology of the pituitary gland. Here we review the characteristics of FSCs and their uncertain functions in the adenohypophysis, with focus on the present research points that we consider fundamental, such as their importance as stem cells, in the process of maturation and aging, and in the pathogenesis of pituitary tumors.

Pars Distalis and Pars Tuberalis Thyroid-Stimulating Hormones and Their Roles in Macro-Thyroid-Stimulating Hormone Formation

“…They possess TSH receptors and are suspected to be involved in the fine-tuning of PD-TSH through ultrashort feedback. They are unique in the way that they express S-100 and glial fibrillary acidic protein (GFAP), secrete growth factors (vascular endothelial growth factor, fibroblast growth factor, and IL-6) and have phagocyte and self-renewal capability [24]. This combination led to the assumption that FSCs play a role in the immune system and further act as stem cells contributing to the maintenance of hormonal cells.…”

The Microenvironment of Pituitary Tumors—Biological and Therapeutic Implications

“…Folliculostellate (FS) cells are resident non-endocrine cells that comprise 5–10% of the normal anterior pituitary and are also found in the TME of pituitary tumors [50,51,52,53,54]. They are identified based on morphological criteria (either having star-like processes and/or forming follicles when they come together) and on their immunoreactivity for the S100 protein [55,56].…”

“…Since the identification of the S100 protein as a marker, FS cells have been shown to be immunoreactive to other markers such as glial fibrillary acidic protein (GFAP), major histocompatibility (MHC) class II surface antigens, cytokeratins, and vimentin, and to produce numerous bioactive molecules [56,57,58,59]. Due to the differential expression of these markers and molecules, FS cells are currently considered to be phenotypically and functionally heterogeneous [54,56,57], with three main subtypes being proposed: astrocyte-like (also expressing GFAP), dendritic cell-like (also expressing MHC class II), and epithelial cell-like (also expressing cytokeratins) [57,59,60,61]. In the normal anterior pituitary, FS cells are mainly associated with the regulation of the hormone secretion of endocrine cells [57], but they have also been implicated in the microcirculation of ions, nutrients, and waste products [58].…”

Does repeated gold-nanoparticles administration affect pars distalis hormonal and folliculo-stellate cells in adult male albino rats?

“…The non-hormonal cells, also called chromophobes, include the recently degranulated cells, the actively hormone-secreting cells or folliculo-stellate cells (FSCs) which represent 5-10% of all anterior pituitary cells [18]. FSCs are star-shaped cells that surround colloid-filled follicles representing cellular debris.…”

“…Moreover, they probably participate in the control of the transport of the hypothalamic stimulatory and inhibitory factors to the pituitary secretory cells and the conveyance of the hormonal products of these cells to the peripheral tissues. The FSCs have phagocytic ability for the cellular debris and apoptotic bodies of the endocrine cells and can act as stem cells for these cells [14,18].…”