Characterization of morphology and angiogenesis in follicles of mares during spring transition and the breeding season

Watson, E.D.; Al-Zi'abi, MO

doi:10.1530/rep.0.1240227

Cited by 48 publications

(42 citation statements)

References 3 publications

(1 reference statement)

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“…This was confirmed in the present study by the higher plasma concentrations, and the highly significant correlation between plasma and follicular concentrations in cyclic mares. The lack of correlation in transitional mares probably reflects the lower vascularity of transitional follicles (Watson & Al-zi'abi 2002). We conclude therefore that the changes seen in expression of IGF-I mRNA in transitional and cyclic follicles may have little effect on its intrafollicular concentrations, because of the high levels present in serum.…”

Section: Discussionmentioning

confidence: 72%

Insulin-like growth factors-I and -II and insulin-like growth factor-binding protein-2 in dominant equine follicles during spring transition and the ovulatory season

Watson

Bae²,

Thomassen³

et al. 2004

Reproduction

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The period between seasonal anoestrus and cyclicity is characterized in many mares by cyclical growth and regression of large dominant follicles. The insulin-like growth factor (IGF) system plays a key role in follicular growth and regression; therefore, we hypothesized that changes in the IGF system and its binding proteins would modulate onset of cyclicity in mares. Ovaries were obtained from pony mares on the day after detection of an actively growing 30 mm transitional anovulatory follicle, and also at the second or third oestrus of the breeding season on the day after the preovulatory follicle reached 30 mm in diameter. Size of dominant follicles at the time of removal was similar in transition (32 6 0.8 mm) and at oestrus (34 6 0.6 mm). IGF-I mRNA was present in granulosa cells, with low thecal expression, whereas IGF-II mRNA was confined to the theca layer. Expression of IGF-I and -II mRNAs, and intrafollicular concentrations of oestradiol, were lower (P < 0.01; paired t test) in transitional anovulatory follicles than in preovulatory follicles. Messenger RNA encoding IGFBP-2 was present in both theca and granulosa layers. Steady-state concentrations of mRNA encoding IGFBP-2 mRNA increased (P < 0.001) in theca in preovulatory follicles. Intrafollicular concentrations of IGFBP-2 were higher (P < 0.001) in transitional than in preovulatory follicles. The similarity in circulating concentrations of IGF-I in transitional and cyclic mares, suggested that the somatotrophic axis is not involved in transition from anovulatory to ovulatory cycles. The results suggest that the increased expression of IGF-I and -II mRNAs in preovulatory follicles, along with the decrease in IGFBP-2 concentrations, could increase the bioavailability of intrafollicular IGF in large follicles during the breeding season, and support our hypothesis that intrafollicular IGF bioavailability must exceed a threshold level before ovulation can occur.

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Section: Discussionmentioning

confidence: 72%

Insulin-like growth factors-I and -II and insulin-like growth factor-binding protein-2 in dominant equine follicles during spring transition and the ovulatory season

Watson

Bae²,

Thomassen³

et al. 2004

Reproduction

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“…The somatic (granulosa/ theca) PI was calculated as the percentage of Ki-67-positive granulosa or theca cells on the number of total somatic cells in the relative compartment. As a consequence, for each follicle, the PI was expressed either for theca or granulosa layers (Wulff et al 2001, Watson & Al Zi'abi 2002. Moreover, the proportion of PEs was calculated as the percentage of PEs (number of dual-stained cells for Ki-67 and vWF) on the total number of proliferating theca cells (PE/PT; Wulff et al 2001, Bauer et al 2003.…”

Section: Ki-67 and Vwfmentioning

confidence: 99%

Vascular supply as a discriminating factor for pig preantral follicle selection

Martelli¹,

Bernabò²,

Berardinelli³

et al. 2009

Reproduction

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This research analyses how somatic and vascular compartments change during preantral follicle growth. To address this aim, theca-granulosa (somatic) proliferation indexes (PIs), proportion of proliferating endothelial cells (PE), vascular area (VA) and vascular endothelial growth factor A (VEGFA) expression were simultaneously recorded on single healthy preantral follicles, classified into six different stages on the basis of the diameter and the granulosa layers. An autonomous blood vessel network starts to appear only in class 3. Vascular remodelling requires VEGFA expression, and VEGFA mRNA and VA significantly increase between class 3 and classes 4 and 5 and, further, in class 6. In addition, a positive correlation exists between these parameters in classes 3-5. Despite variation in angiogenesis results from classes 3 to 5, the statistical analysis reveals that the vascular parameters are positively and strictly correlated with somatic PIs. Conversely, class 6, also characterized by higher values of somatic PIs, displays a stable proportion of PEs (y40%) without showing any correlation among the different parameters analysed. To identify follicular subpopulations within different classes, a multivariate hierarchical cluster analysis was performed. This analysis reveals that the majority of classes 3 and 4 are quiescent follicles or structures that grow very slowly. Class 5 represents a transitory category, where half of the follicles maintain a low activity and the remaining express significantly higher levels of granulosa PI and VA. The follicles with this high activity are probably able to reach class 6 becoming dominant structures where somatic and vascular parameters are constantly on high levels and the VA remains the unique differentiating element.

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“…Only in the recent past, studies on microvascularization of the mare's reproductive tract, such as the endometrium, follicles and corpus luteum have been carried out [18][19][20][21]. As the corpus luteum (CL) growth and its endocrine function are closely dependent on the formation of new capillaries, their dysfunction might be related to a deficient vascularization.…”

Section: Introductionmentioning

confidence: 99%

Microvascularization and angiogenic activity of equine corpora lutea throughout the estrous cycle

Ferreira‐Dias¹,

Pinto‐Bravo²,

Mateus³

et al. 2006

Domestic Animal Endocrinology

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Corpus luteum growth and endocrine function are closely dependent on the formation of new capillaries. The objectives of this study were to evaluate (i) tissue growth and microvascular development in the equine cyclic luteal structures; (ii) in vitro angiogenic activity of luteal tissues in response to luteotrophic (LH, PGE 2 ) and luteolytic (PGF 2␣ ) hormones and (iii) to relate data to luteal endocrinological function. Our results show that microvascular density was increased in the early and mid luteal phase, followed by a fall in the late luteal phase and a further decrease in the corpus albicans. Hyperplasia of luteal tissue increased until the mid luteal phase and it was followed by tissue regression. Luteal explants were cultured with no hormone added, or with PGF 2␣ , LH, PGE 2 , LH + PGE 2 or LH + PGF 2␣ . Media conditioned by equine luteal tissue from different stages of the luteal phase were able to stimulate mitogenesis of bovine aortic endothelial cells (BAEC), suggesting the presence of angiogenic activity. No difference was observed among luteal structures on their mitogenic capacity, for any treatment used. Nevertheless, Late-CL conditioned-media with PGF 2␣ showed a significant decrease in BAEC proliferation (p < 0.05) and LH + PGF 2␣ a tendency to reduce mitogenesis. Thus, prostaglandin F 2␣ may play a role on vascular regression of the CL during the late luteal phase in the * Corresponding author. Tel.: +351 213652859; fax: +351 213652889. -mail address: gmlfdias@fmv.utl.pt (G. Ferreira-Dias Ferreira-Dias et al. / Domestic Animal Endocrinology 30 (2006) [247][248][249][250][251][252][253][254][255][256][257][258][259] mare. These data suggest that luteal angiogenesis and vascular regression in the mare are coordinated with the development of non-vascular tissue and might be regulated by many different factors. E

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Characterization of morphology and angiogenesis in follicles of mares during spring transition and the breeding season

Cited by 48 publications

References 3 publications

Insulin-like growth factors-I and -II and insulin-like growth factor-binding protein-2 in dominant equine follicles during spring transition and the ovulatory season

Insulin-like growth factors-I and -II and insulin-like growth factor-binding protein-2 in dominant equine follicles during spring transition and the ovulatory season

Vascular supply as a discriminating factor for pig preantral follicle selection

Microvascularization and angiogenic activity of equine corpora lutea throughout the estrous cycle

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