Ovaries maintain and produce functional female gametes, oocytes, for fertilisation. Oocytes develop inside cellular assemblies, the ovarian follicles, before birth and can reside there for up to 50 years in the human. Despite recent inroads, the precise mechanisms of initial follicle recruitment and growth remain unclear. Although the pituitary gonadotrophins play a role in this developmental process, locally produced factors have been implicated strongly in initiation of follicle growth. It is known that fibroblast growth factor 2 (FGF2) is a powerful mitogen for follicular granulosa cells in culture and initial studies undertaken in this project were successful in detecting FGF2 gene expression in ovarian biopsies from fertile healthy women. To further elucidate which cells were expressing FGF2, laser microdissection was employed to isolate differentially staged follicle populations. Real-time RT-PCR was used to quantify mRNA in relation to follicle development. Decreasing levels of FGF2 expression were detected as follicles developed. Non-radioactive in situ hybridisation confirmed FGF2 mRNA localisation in granulosa cells of preantral follicles. FGF2 protein localisation was assessed with immunohistochemistry; two primary antibodies raised against different fragments of human FGF2 were used. Both antibodies detected FGF2 in the oocyte cytoplasm of putative non-growing follicles, whereas only one of the antibodies showed additional reactivity to the basement membrane region of these same follicles. These results suggest different isoforms of FGF2 may localise specifically to different cellular sites.
Follicle stimulating hormone receptor (FSHR) gene expression was also investigated in follicles using laser microdissection, real-time RT-PCR and in situ hybridisation. FSHR mRNA was detected in all follicle populations, including the smallest putative non-growing follicles. Disparity to other published works was attributed to the position of primer annealing, and thus the ability to detect alternatively spliced transcripts.
In conclusion, the work presented here provides evidence that FGF2 and FSHR are present in small follicles and that their actions may be stimulatory or inhibitory to initial follicle recruitment.
| Identifer | oai:union.ndltd.org:ADTP/217420 |
| Date | January 2006 |
| Creators | Quennell, Janette Henrietta, n/a |
| Publisher | University of Otago. Department of Anatomy & Structural Biology |
| Source Sets | Australiasian Digital Theses Program |
| Language | English |
| Detected Language | English |
| Rights | http://policy01.otago.ac.nz/policies/FMPro?-db=policies.fm&-format=viewpolicy.html&-lay=viewpolicy&-sortfield=Title&Type=Academic&-recid=33025&-find), Copyright Janette Henrietta Quennell |
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