1. In vitro culture and in vitro maturation of mouse preantral follicles with recombinant gonadotropins 
Hung-Ching Liu, Ph.D., Zhiying He, M.S., Zev Rosenwaks, M.D. 
Fertility and Sterility 
Volume 77, Issue 2, Pages (February 2002)
DOI: /S (01)

2. FIGURE 1
Morphology of viable and atretic follicles after culture in vitro. Preantral follicles were able to survive in media containing gonadotropins or insulin alone. Follicles were considered to have survived if their structure remained normal, with close contact between the oocyte and the surrounding granulosa cells (A), and were considered to be atretic if there was disruption of intracellular contact, with oocyte and granulosa cells causing the release of oocytes from the follicles (B).
Liu. IVM of follicles to generate competent oocytes. Fertil Steril 2002.
Fertility and Sterility  , DOI: ( /S (01) )

3. FIGURE 2
In vitro culture of preantral follicles. The isolated preantral follicles (a) contained central GV-stage oocytes surrounded by two to five layers of granulosa cells within a basal membrane and attached with a few flat theca cells. On days 1–2, theca cells formed a monolayer base under the follicles to immobilize the follicles (b). From day 4 on, granulosa cells gradually spread out of the basal membrane and grew over the thecal monolayer (c). From day 6 on, an antral-like cavity (indicated by arrows), a translucent area in the granulosa cell mass around the oocytes, was formed in some of the follicles. (d), A follicle at early antral formation stage. From day 10 on, the antral-like structure (A) formed around oocyte was fully developed (e). At this stage, the granulosa cells have clearly differentiated into the mural granulosa cells (M) and cumulus cells (C) surrounding the oocyte (O). On day 12, release of COCs from antral follicles (f) can be stimulated by administering hCG-EGF.
Liu. IVM of follicles to generate competent oocytes. Fertil Steril 2002.
Fertility and Sterility  , DOI: ( /S (01) )

4. FIGURE 3
E2 production of follicles matured in vitro. Isolated preantral follicles were cultured in conditions A, B, and C as described in text, with media changed daily or every other day. Cultured follicles began to secrete E2 from day 4. Secretion increased progressively as the follicles grew to more advanced stages. (A), The results with medium changed daily. (B), The results with media changed every other day. The sharp drop of E2 secretion from day 10 to day 12 in B indicates the rapid onset of granulosa cell atresia caused by insufficient nutrition. (Group A, ■; group B, □; and group C, ▨.)
Liu. IVM of follicles to generate competent oocytes. Fertil Steril 2002.
Fertility and Sterility  , DOI: ( /S (01) )