Novel Action of FSH on Stem Cells in Adult Mammalian Ovary Induces Postnatal Oogenesis and Primordial Follicle Assembly

Figure 1

FSH-FSHR3-stem cell interaction in ovary surface epithelium. (a) H&E stained sheep OSE smear. Two distinct populations of stem cells (encircled) including VSELs (arrow) which are smaller than the red blood cells and slightly bigger OGSCs (asterix) are clearly visualized even after gently scraping sheep ovary fixed overnight in neutral buffered formalin. Red blood cells and epithelial cells are also clearly visualized [12]. (b) (i)–(vi) Characterization of ovarian stem cells using pluripotent OCT-4 and SSEA4 markers. Smaller VSELs express nuclear OCT-4 and cell surface SSEA4 whereas slightly bigger OGSCs express cytoplasmic OCT-4 and minimal SSEA4. Note the VSELs do not stain with DAPI [13]. (c) (i) Sheep OSE smear immunostained with FSHR antibody. Note epithelial cells are negative whereas the stem cells exhibit distinct positive stain. (ii) Confocal microcopy localization of FSHR on VSELs and OGSCs and on a germ cell nest. (iii)-(iv) In situ hybridization of FSHR on ovarian stem cells after FSH treatment using oligo probes specific for FSHR1 and FSHR3, respectively. Note active transcription of FSHR3 mRNA in the cytoplasm of stem cells after FSH treatment whereas FSHR1 is expressed in the stem cells and the expression is not affected by FSH treatment. (d) qRT-PCR analysis of FSHR1 and FSHR3 after 3 and 15 h of FSH treatment. Note that only FSHR3 levels are increased transiently after 3 and return to basal levels by 15 h. (c) and (d) Panels show earlier published from 3 different experiments represented individually by Patel et al. [14]. Please refer to the cited references for further details.

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