The estrogen-injected female mouse: new insight into the etiology of PCOS

Table 1 The prevention of follicular cysts in estrogen-injected (C57BL/6J × A/J) F₁ (B6A) female mice by thymectomy and thymocyte replacement.

	Condition of Ovaries
Treatment	CLs	Dysgenic	Cysts	Other
1. Sesame oil Days 5–7 [8]^a	100%^b (14.7 ± 1.4)^c	------	------	------
2. E2 Days 5–7 [17]	------	------	100% (10.8 ± 0.3)	------
3. Tx-3 [19]	47% (11.8 ± 0.6)	53% (2.6 ± 0.6)	------	------
4. Tx-3 + thymocytes from 7 day-old females [8]	13% (5.8)	------	63% (5.5 ± 0.8)	24% (3.9 ± 0.8)^d
5. Tx-3 + E2 Days 5–7 + thymocytes from 7-day-old females [7]	14% (1.9)	43% (1.8 ± 0.8)	14% (5.9)	29% (2.0 ± 1.0)^e
6. Tx-3 + thymocytes from adult females [18]	100% (9.9 ± 0.6)	------	------	------
7. Tx-3 + E2 Days 5–7 + thymocytes from adult females [11]	73% (12.4 ± 1.8)	------	------	27% (7.8 ± 0.3)^f

Mice in treatments (1) and (2) were injected sc at 5–7 days of age with either sesame oil: ethanol (9:1; v:v) {vehicle}, or vehicle containing 20 μg estradiol-17β (E₂). In treatment (3), the females were thymectomized at 3 days of age (Tx-3). Treatments (4) and (6) consisted of infusing 15-day-old Tx-3 mice with 20 million thymocytes, isolated from thymuses of either 7-day-old or adult female B6A donors. In treatments (5) and (7), Tx-3 females were injected with E₂ at 5–7 days of age, and then infused with 20 million thymocytes, isolated from thymuses of either 7-day-old or adult female B6A donors. All recipient females were killed at 100 days of age and ovaries removed and examined histologically for corpora lutea (CLs), follicular cysts, and dysgenesis. Normal ovaries contained normal follicle populations and CLs. Dysgenic ovaries lacked all follicle populations. Cystic ovaries contained follicular cysts, and lacked CLs.
^aNumber of animals in each group.
^bPercentage of animals with similar ovarian histology.
^cAverage weight of paired fixed ovaries (mg ± S.E.M.).
^dOvaries with cysts and CLs.
^eDysgenic ovaries with cysts.
^fOvaries with normal follicle populations, but lacking both CLs and follicular cysts.

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