FIG. 3.

Timing of individual follicle formation differed between ventral and dorsal regions of the mouse ovary. A) Differences between dorsal and ventral ovarian regions identified using immunofluorescence assay with MVH (germ cell), FOXL2 (pregranulosa), and laminin (basal lamina) antibodies in serial sections. Arrow highlights the specification of the medulla at 16.5 dpc. Arrowhead shows higher density of FOXL2-expressing cells in the dorsal region even before specification of the medulla. Double-arrowheads highlight dorsal-ventral differences in laminin organization. 14.5 dpc, n = 9; 16.5 dpc, n = 7; 18.5 dpc, n = 9. Bar = 200 μm. B) Individual follicle formation at 18.5 dpc was restricted to the dorsal region of the ovary, visualized using MVH (green; i and iii) and FOXL2 (green; ii and iv). Arrows represent individual primordial follicles. The images in i/ii and iii/iv are adjacent sections separated by 5 μm. Bar = 50 μm. C) Spatial differences in development between the center and the periphery of the dorsal region at 18.5 dpc (i) along with details of the germ cell clusters at the periphery (ii and iv) and individual follicles in the center (iii and v). Arrows highlight the presence of individual follicles. Red, p63 (oocyte nucleus); green, laminin; blue, DAPI. A, anterior; P, posterior. Bar = 100 μm (i) and 50 μm (ii–v).