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J Cowling

Publications and source records attributed to J Cowling.

5 recordsLinked to original sources
PubMed1992

Studies on basic fibroblast growth factor (FGF-beta) gene expression in the rat and pig ovary using in situ hybridization and quantitative reverse transcriptase--polymerase chain reaction techniques.

In order to gain further understanding of the physiology of basic fibroblast growth factor (FGF-beta) in the mammalian reproductive tract, the expression of FGF-beta mRNA in the rat and porcine ovary has been examined by in situ hybridization and quantitative reverse transcriptase-polymerase chain reaction techniques during different stages of the estrus cycle. The results confirm that an increase in FGF-beta mRNA levels occurs over the course of the estrus cycle. No FGF-beta gene expression was detected during diestrus, the non-hormonal phase of the cycle, or at the early proestrus stage of the cycle. During late proestrus and estrus, FGF-beta mRNA was predominantly localized to granulosa cells of the dominant follicles, and to a lesser extent, to secondary antral follicles not committed to ovulation. These cells also expressed FGF-beta mRNA during this phase of follicular development, albeit in low abundance. During metestrus, after ovulation, in the newly formed corpora lutea FGF-beta mRNA levels were maximal, however on entering the next cycle commencing at diestrus, no FGF-beta mRNA was observed in the degenerating corpora lutea. These results indicate that expression of the FGF-beta gene is differentially regulated during the estrus cycle. The biological significance of this expression and the potential role of FGF-beta in local intra-ovarian regulation of the repetitive cycles of follicular differentiation, proliferation and maturation associated with ovarian revascularization are discussed.

Animals↗
PubMed1992

The role of basic fibroblast growth factor in skeletal muscle regeneration.

Muscle growth and regeneration is controlled by locally produced growth factors which activate satellite cells and stimulate their proliferation, differentiation and fusion to form mature myotubes. Basic fibroblast growth factor (bFGF) has been previously shown to promote proliferation and inhibit differentiation of myoblasts in vitro. In comparison, the in vivo role of this growth factor is less well documented. In the present investigation on the role of bFGF in muscle regeneration, bFGF mRNA levels were studied in two experimental systems: (1) primary cell cultures derived from rat skeletal muscles, and (2) an in vivo rat muscle injury model. bFGF mRNA was detected in myoblasts just prior to fusion and in myotubes of primary muscle cell cultures. In the non-injured muscle, bFGF mRNA transcripts were detected in myotubes but not satellite cells. In the in vivo muscle injury model bFGF mRNA was observed in myoblasts and in degenerating and regenerated myotubes. The significance of these experimental results in terms of the role played by bFGF in the myogenic program in vivo are discussed.

Animals↗
PubMed1992

Localization of bFGF mRNA in cyclic rat ovary, diethylstilbesterol primed rat ovary, and cultured rat granulosa cells.

Evidence from in vitro studies strongly implicates basic fibroblast growth factor (bFGF) as a local regulator of ovarian function. However, the in vivo function of this growth factor in the ovary is uncertain. The objective of this study has thus been to investigate the biological role of bFGF in the rat ovary by monitoring bFGF gene expression using in situ hybridization in 3 systems; (1) the naturally cycling ovary, (2) ovaries of immature rats treated with diethylstilbesterol (DES), and (3) primary rat granulosa cell cultures. The rat estrus cycle can be divided into 4 stages as determined by vaginal cytology; diestrus, proestrus, estrus and metestrus. bFGF mRNA transcripts were localized to granulosa and theca cells of developing follicles during proestrus and estrus and in the corpus luteum following ovulation during metestrus. The estrogen analogue DES induced extensive in vivo folliculogenesis and high levels of bFGF mRNA in both granulosa and theca cells when compared to controls. Detectable levels of bFGF mRNA were also observed in primary granulosa cell cultures grown to high density. Employment of this in situ hybridization procedure has enabled the in vivo cellular sources of bFGF mRNA to be identified and the time course of expression during the estrus cycle to be monitored. The biological significance of this expression and the interplay between bFGF, extra- and intra-ovarian modulators are discussed.

Animals↗