Estrogen receptor 2 (ESR2) plays significant biological roles in the reproductive system and ovarian follicle development. This study, therefore, aimed to reveal the expression pattern and cell-specific localization of ESR2 in the ovarian follicles of Leizhou black ducks.
Four laying Leizhou black ducks at 43 weeks old were annihilated and different grade-sized follicles were collected for immunohistochemistry and expression profile study. The follicles were grouped into seven (7) as small white follicles (SWF), large white follicles (LWF), small yellow follicles (SYF), large yellow follicles (LYF), follicle 5 (F5), follicle 2 (F2), and follicle 1 (F1).
The qRT/PCR results displayed that ESR2 mRNA was expressed in all follicles with the highest (P < 0.05) level of expression found in F1 compared to other follicles. Immunohistochemistry analysis of the cell-specific localization of ESR2 protein revealed that ESR2 was distributed in both granulosa and theca cells region in all the follicles examined. There was a significantly higher localization of ESR2 protein in the granulosa cells than the theca cells of SWF, SYF, LYF, F2, and F1. Comparatively, ESR2 was highly expressed in the granulosa cells of LYF than in all the other follicles.
These results provide theoretical knowledge for the in-depth study of the related biological functions of the ESR2 gene and its application at the cellular level.