(C) The follicles with PAS-positive colloids inside (arrowheads) are surrounded by one or two layers of endocrine cells (arrows) and blood vessels (v). stellate-like in shape and exhibited short cytoplasmic processes that contacted with blood vessels and endocrine cells. In addition, some follicular colloids were immunostained with anti-S-100 protein. A few FSC were immunostained with anti-glial fibrillary acidic protein (GFAP) and anti-vimentin. The morphometric parameters analyzed (percentages of S-100-positive total, cellular and colloidal areas) increased from sector 1 to sector 3 and then decreased to sector 5. Hormone secreting cells, mainly lactotrophs, gonadotrophs and corticotrophs were associated with FSC and follicles. The ultrastructural study exhibited that FSC developed junctional complexes and desmosomes between their lateral membranes. Lanthanum freely penetrated the spaces between granulated cells and FSC, but did not penetrate into the follicular lumen. In conclusion: 1) the differential expression of S-100 protein, GFAP and vimentin may indicate different physiological stages of FSC; 2) the expression of these proteins suggests a neuroectodermic origin of these cells; 3) FSC spatial distribution, association with endocrine cells, and the generation of an intercellular communication network suggest that FSC are involved in the pituitary pars distalis paracrine regulation of the viscacha. family. This rodent inhabits the southern hemisphere from Paraguay through central Argentina.21,22 In its natural habitat, the viscacha is a seasonal breeder.23C27 The pituitary pars intermedia (PI), pineal gland, and blood-testis barrier of this rodent SPDB have been studied using lanthanum.28C30 Piezzi exhibited two regions: ventral (anterior) and dorsal (posterior, close SPDB to Rathke’s pouch). In addition, two extremes were distinguished: a cephalic one (superior, connected with pars tuberalis) and a caudal one (substandard; Physique 2 A). The PD parenchyma showed good development of vascular irrigation and scarce connective tissue. Large blood vessels were observed in the cephalic extreme (Physique 2 B), which branched out along the PD parenchyma and anastomose in the caudal extreme, where the PD becomes narrower. Follicles with PAS-positive colloid-like material inside were surrounded by one or two layers of endocrine cells and blood vessels (Physique 2 C). The follicles were mainly localized in the PD extremes. Some blood vessels communicated the PD with the PI and pars nervosa (PN; Physique 2 D). Open in a separate window Physique 2 Sections of the pituitary of adult male viscacha stained SPDB with Hematoxylin-PAS technique. (A) The image shows: pars distalis (PD), pars intermedia (PI), pars nervosa (PN) and Rathke’s pouch (r). The regions and extremes of the pituitary PD are shown: vr, ventral region; dr, dorsal region; ce, cephalic extreme; ca, caudal extreme. (B) Higher magnification of the upper insert in Physique A. Long blood vessels (v) branch out in PD are observed. Arrowheads: PAS-positive colloid. (C) The follicles with PAS-positive colloids inside (arrowheads) are surrounded by one or two layers of endocrine cells (arrows) and blood vessels (v). (D) Higher magnification of the lower insert in Physique A. Blood vessels (v) that communicate pars distalis (PD) with both pars intermedia (PI) and pars nervosa (PN) are observed. r: Rathkes pouch. Level bars: A = Rabbit Polyclonal to PKC zeta (phospho-Thr410) 500 m; B and D = 100 m; C = 25 m. Immunohistochemistry Immunostaining for the S-100 protein was positive in FSC and some follicular colloid of PD and PI, as well as in the pituicytes of PN (Physique 3 A). Most of the FSC of PD were immunostained with anti-S-100 protein in both nucleus and cytoplasm, while a few cells expressed this protein only in the nucleus or only in the cytoplasm. FSC originated follicles and were occasionally isolated or in small groups. They exhibited a stellate-like shape, irregular nucleus and short cytoplasmic processes that contacted endocrine cells and blood vessels. Most of the follicles in both pituitary extremes showed heterogeneous S-100 protein immunostaining of the follicular colloid (Physique 3 BCD). On the other hand, a small number of FSC in the PD parenchyma were immunostained with anti-GFAP in the cytoplasm surrounding the nucleus (Physique 3 ECF), and with anti-vimentin in the cytoplasm, mainly in the cytoplasmic processes (Physique 3 GCH). In addition, in each follicle only a few FSC exhibited immunostaining for GFAP and vimentin. Neither GFAP nor vimentin were expressed in the follicular colloid (Physique 3 ECH). Open in a separate window Physique 3 Immunohistochemistry for S-100 protein (ACD), GFAP (ECF) and vimentin (GCH) in pituitary pars distalis of viscacha. (A) The immunostaining for S-100 protein is observed in the FSC and some follicular colloid (arrowheads) of pars distalis (PD) and pars intermedia (PI). The pituicytes (arrows) of pars nervosa (PN) also exhibit immunostaining for this protein. r: Rathke’s pouch. (B) FSC (arrows) immunostained with anti-S-100 protein forming follicles surrounded by blood vessels (v). The follicular colloid (F) presents heterogeneous immunostaining for this protein. (C) Short cytoplasmic processes (P) of the FSC are.