Tral follicles appeared to have mostly negative c-kit staining. C-kit immunostaining
Tral follicles appeared to have mostly negative c-kit staining. C-kit immunostaining did not appear visually different in PCOS antral follicles compared to non-PCOS. Although this represents a small set of observations, the results are suggestive of an aberrant KITL/c-kit signalling axis in PCOS.- negative; + weak; ++ moderate; +++ strong; n/a none available OOC, oocyte; GC, granulosa cells; TH; theca layerDiscussion This study demonstrates that the c-kit/KITL signalling pathway is expressed at multiple stages of follicular development in adult, reproductive age human ovaries. Moreover, this is the first study to document the presence of specific c-kit and KITL isoforms in human ovarian tissue. Their presence in CBR-5884 biological activity preantral and antral follicle stages is indicative of their involvement in human folliculogenesis. Unlike mouse ovaries, in which c-kit and KITL are expressed in distinct cellular compartments and signal exclusively in a paracrine manner, the expression pattern of c-kit and KITL in human ovaries displayed a less celltype specific distribution. Human granulosa, theca and stromal cells all displayed at least some weak staining for both proteins, suggesting that autocrine signalling occurs in these cells types. The presence of c-kit proteinTuck et al. Journal of Ovarian Research (2015) 8:Page 7 ofFig. 2 c-kit and KITL are present in preantral follicles. Representative images of c-kit (a, c) and KITL (b, d) immunostaining in primordial (a, b) and primary (c, d) follicles. O: oocyte; G: granulosa cells. The open arrow indicates a primordial follicleFig. 3 c-kit and KITL are present in antral follicles. Representative images of c-kit (a, c) and KITL (b, d) immunostaining at low (a, b) and high (c, d) magnifications. A: antrum; G: granulosa cells; T: theca layer; S: stromaTuck et al. PubMed ID:http://www.ncbi.nlm.nih.gov/pubmed/27385778 Journal of Ovarian Research (2015) 8:Page 8 ofFig. 4 c-kit and KITL are expressed during various stages of atresia. (a, b) Intact granulosa layer, theca layer and basal lamina. (c, d) Disassociating granulosa cell layer with pyknotic nuclei. (e, f) Atretic follicle with little remaining of the granulosa layer and no distinction between the basal lamina and theca layer. A: antrum; G: granulosa cells; BL: basal lamina; T: theca layer; S: stromain adult granulosa cells is supported by previous studies, which demonstrated the presence of c-kit mRNA and protein in pregranulosa cells and granulosa cells of primordial follicles in human fetal ovaries [12, 14, 37]. This finding suggests that the roles of KITL previously established in animal models may also be present in the human ovary, and furthermore, that these functions are perhaps regulated in a differential manner (e.g., autocrine versus paracrine). Given that KITL promotes preantral follicle growth and oocyte development [1, 38?0], human preantral follicles that are positive PubMed ID:https://www.ncbi.nlm.nih.gov/pubmed/28300835 for granulosa cell c-kit may possess a selective advantage over follicles that do not express the KITL receptor. c-kit and KITL protein was also found to be coexpressed in the theca layer of all antral follicles. This suggests that the roles of KITL in formation and function of the theca layer, as shown in the bovine ovary[41?3], may remain conserved in the human ovary. In contrast, a study examining c-kit immunostaining in human adult ovaries did not show any c-kit protein in the theca layer [12]. This is most likely due to the primary antibody used, ACK-2, which has been utilised primarily to inhibit c-kit in in vivo mechanistic stud.
