Microvascularization and Expression of Fibroblast Growth Factor and Vascular Endothelial Growth Factor and Their Receptors in the Mare Oviduct

Abstract

The oviduct presents the ideal conditions for fertilization and early embryonic development. In this study, (i) vascularization pattern; (ii) microvascular density; (iii) transcripts of angiogenic factors (FGF1, FGF2, VEGF) and their receptors—FGFR1, FGFR2, KDR, respectively, and (iv) the relative protein abundance of those receptors were assessed in cyclic mares’ oviducts. The oviductal artery, arterioles and their ramifications, viewed by means of vascular injection-corrosion, differed in the infundibulum, ampulla and isthmus. The isthmus, immunostained with CD31, presented the largest vascular area and the highest number of vascular structures in the follicular phase. Transcripts (qPCR) and relative protein abundance (Western blot) of angiogenic factors fibroblast growth factor 1 (FGF1) and 2 (FGF2) and vascular endothelial growth factor (VEGF), and their respective receptors (FGFR1, FGFR2, VEGFR2 = KDR), were present in all oviduct portions throughout the estrous cycle. Upregulation of the transcripts of angiogenic receptors FGF1 and FGFR1 in the ampulla and isthmus and of FGF2 and KDR in the isthmus were noted. Furthermore, in the isthmus, the relative protein abundance of FGFR1 and KDR was the highest. This study shows that the equine oviduct presents differences in microvascular density in its three portions. The angiogenic factors VEGF, FGF1, FGF2 and their respective receptors are expressed in all studied regions of the mare oviduct, in agreement with microvascular patterns.

Equine Endothelial Cells Show Pro-angiogenic Behaviours in Response to FGF2 but Not VEGF-A

“…Both FGF and VEGF-A are potent pro-angiogenic stimuli for human ECs [19,20,[57][58][59] and receptors for these growth factors are expressed at similar levels in human ECs [60]. In the horse, levels of FGFR1, FGFR2 and VEGFR2 expression have been studied in the oviduct at different sites and different stages of the estrous cycle [61]. At each site and each time point, the mRNA expression level, relative to β2-microglobulin, was lower for VEGFR2, than for either FGFR1 or FGFR2, in agreement with the lower VEGFR2 expression seen in EAoECs in this study.…”

Collagen and Microvascularization in Placentas From Young and Older Mares

“…The obtained cDNA was combined with Power SYBER Green PCR Master Mix (Ref. 4368706; Applied Biosystems, Waltham, Massachusetts, USA) and with the target or reference genes, and qPCR assays of both were performed simultaneously in a StepOne-Plus TM Real-Time PCR System (Applied Biosystems, Waltham, Massachusetts, USA), using the universal temperature cycles previously described ( 28 ).…”

“…This stain has been largely used as a marker of endothelial cells, since it strongly reacts with carbohydrates present in the microvascular basement membrane ( 35 ). In this study, blood vessel walls were considered equally regardless of their nature (arterioles, venules, or capillaries) ( 28 ). The histological slides were observed under light microscopy and photographed at a total magnification of 100x, for further imageJ program analysis.…”

“…On the same micrograph areas, the number of vessels present were also counted. Mean values of total vascular area and total blood vessel number for each placenta region were further considered for statistical analysis ( 28 , 36 ).…”

Identification of key genes and biological pathways in different parts of yak oviduct based on transcriptome analysis

“…These have similar histological structures, but different physiological functions in vivo . The expression of oviduct-specific mRNAs varies in different regions ( 1 ); VEGF, FGF1, FGF2, and their receptors are expressed in all three parts of the equine oviduct ( 2 ). Hormones also have important effects on oviduct movement, particularly in the follicular phase; OTR and oxytocin exhibit significant stimulatory effects on cow oviduct movement ( 3 ).…”