Abstract
The follicular development and oocyte maturation were examined during the period of ovulation in immature rats pretreated with PMS. Immature female Wistar rats 2426 days of age were given PMS (3 i. u.) at 10:00 h. Animals were killed at various times after treatment with PMS (Table 1), and ovaries were prepared for serial sections at 10 μ and stained with hematoxylin-eosin. Two diameters of follicles were measured in the section in which the nucleolus of the oocyte was found. All the follicles over 300μ of the diameter were recorded. The oocytes in maturation divisions were classified according to Odor's category. Numbers of the large follicles over 500 μ increased 48 hrs to 60 hrs after PMS injection.
Number of the large follicles decreased slightly 62 h and markedly 72 h, when small follicles (300499 μ) developed again. The maturation division (the breakdown of germinal vesicles) started 55 h after PMS, one hour after the beginning of the LH surge. The timing of each stages of the maturation division during the period of ovulation in immature rats pretreated with PMS occurred in the same relation to that of adult cyclic rats.
