Lymphangiogenesis in mouse embryonic and early postnatal ovaries

The critical importance and remodeling capacity of the blood vasculature within the ovary have been extensively analyzed, while the lymphatic vasculature has received limited attention, and its characteristics were reported by only a few studies.

To investigate the morphological patterns of lymphatic vessel formation in mouse embryonic and early postnatal ovary.

Immunostaining was performed on ovarian tissues from Prox1-EGFP transgenic mice and wild-type mice to investigate the lymphangiogenesis, and the CD31 was employed to label vascular endothelium and LYVE1 and Prox1 as co-markers for lymphatic endothelium.

Prox1⁺ cells, LYVE1⁺ cells, and Prox1-EGFP⁺/LYVE1⁺ vessels were absent in the medulla near the ovarian hilum until P7, and YAP1 was expressed in the nucleus and cytoplasm of granulosa cells, alongside the observation of scattered primary follicles within the ovary. By P10, these markers were abundantly expressed in the ovarian medulla, while YAP1 was localized primarily in the cytoplasm of granulosa cells, alongside the occurrence of secondary follicles. By P14, Prox1⁺ cells, LYVE1⁺ cells, and Prox1-EGFP⁺/LYVE1⁺ vessels extended to the cortex, and YAP1 shifted to the nuclei of granulosa cells, alongside the reaching of follicles to the antral stage. From P14 to P28, these markers exhibited a further increasing trend, while YAP1 localized in the nucleus of granulosa cells, alongside the progress of follicles to the preovulatory stage.

Ovarian lymphangiogenesis in the mouse began on postnatal day 7 and subsequently developed from the medulla to the cortex. Additionally, ovarian lymphangiogenesis occurred in synchrony with follicular maturation, during which YAP1 exhibited an ectopic expression pattern.