Fig. 2

Effects of chronic heat stress on granulosa cells apoptosis and follicular atresia in the ovaries of mice. a TUNEL signals intensities in the follicles of ovaries from control (Con) and heat-stressed (HS) mice after 21 d of treatment: (a, d) follicles with weak apoptotic signals, (b, e) follicles with intermediate apoptotic signals, (c, f) follicles with strong apoptotic signals. Bar = 50 μm. b Effects of heat stress on the number of antral follicles with different apoptosis signal intensities after 21 d of heat treatment. c Morphology of follicles stained with haematoxylin and eosin from ovaries of control and heat-stressed mice. Panels (a-c) Follicles from ovaries of control mice after 21 d of treatment. Panels (d-f) follicles from ovaries of heat-stressed mice after 21 d of treatment. The red triangle indicates healthy antral follicles; the red rectangle indicates healthy pre-antral follicles; the red asterisk indicates atretic follicles. Bar = 50 μm. d The percentage of atretic follicles in the total population of antral follicles on the ovaries after 4 wk of treatment. *indicates P <0.05 compared with the control