FIG. 1.

Expression of the fluorescent proteins changed according to the developmental stage of the germ cell. A) Map of the linear constructs used to generate the triple-transgenic line and design of the genotyping primers. B) Expression of reporter proteins during embryonic development (epifluorescence). Top) Anatomic changes of the ovary and reproductive tract. Bottom) Ventral (V) and dorsal (D) regions of the same ovary, rotated horizontally. A, anterior; P, posterior. Bar = 200 μm. Detail of the cord-like structures (i; arrows highlight germ cell cluster) and specification of a medullar region (ii) in 18.5-dpc ovaries (confocal maximum projections) are shown. M, medulla; C, cortex. Bar in i and ii = 100 μm. C) Fluorescent protein expression in the dorsal ovarian region of different age mouse (epifluorescence). Dashed box highlights the ovarian area where follicles first grow. Different imaging settings were used at D0 to D4 and D6 to D12. A higher EGFP and lower AmCyan and mCherry exposure times were used on D6 and D12 to avoid saturation of the images. Bar = 200 μm. D) Representative follicles in the surface of the ventral region in a 16-day-old mouse ovary (epifluorescence). Follicle stage was determined based on the follicular morphology in the bright-field image. Pr, primordial; Pm, primary; Sc, secondary; At, antral. Bar = 50 μm. E) Small follicles in a 16-day-old mouse ovary (confocal). Primordial follicles (Pr) only express EGFP and mCherry at various levels. DNA probe Hoechst 33342 was used to determine follicle class. Bar = 50 μm.