Figure 4.

Slowing of oocyte-cyst breakdown and elimination of primordial follicles in neonatal XY^sry- ovaries. (A) Representative Masson trichrome (MT) staining of ovarian sections of XX and XY^sry− females at P1. Bottom panels are magnified images of dashed rectangles depicted in the upper panels. White arrows/dashed circles indicate oocyte cysts; arrowheads indicate primordial follicles. Scale bar, 100 μm. (B) TUNEL assay. Representative images of immunostained ovaries from XX and XY^sry− females at P1. Ovaries were stained with an antibody against a germ-cell-specific marker (DDX4, red) and TUNEL (an apoptotic cell marker, green). White arrows/dashed circles indicate oocyte cysts; arrowheads indicate primordial follicles. Scale bar, 20 μm; magnification, ×40. (C) Population percentages of oocytes in either cysts or oocytes in follicles from XX and XY^sry− ovaries at P1. Asterisks indicate statistically significant differences between the groups (chi-squared test:, **P < 0.01, n = 3). (D) Percentages of TUNEL-positive oocytes from P1 XX and P1 XY^sry- ovarian sections. Percentages of apoptotic oocytes (TUNEL-positive) are shown as mean ± standard error of the mean. Asterisks indicate a statistically significant difference between the groups (Student t-test, **P < 0.01, n = 3). (E) Expression patterns of folliculogenesis-related genes from each P1 germ cell RNA-seq dataset with two replicates per sample. Asterisks indicate statistically significant differences in XX oocytes, XY^sry− oocytes, and XY spermatogonia (Tukey–Kramer test, *P < 0.05, **P < 0.01). (F) Representative MT sections of ovaries of P8 XX and XY^sry− females. Bottom panels represent magnified images of dashed rectangles in the upper panels. White arrows indicate primordial follicles; white arrowheads indicate primary follicles. Scale bar, 100 μm. (G) Numbers of respective oocytes per one ovarian section at P8. Asterisks indicate a statistically significant difference between XX and XY^sry− oocytes (Student t-test, **P < 0.01, n = 3).