Immature follicles can be cryopreserved without subsequent DNA fragmentation (Demirci et al., 2002), but the integrity of the granulosa cell structure and function after this process has been questioned (Siebzehnrubl et al., 2000; Navarro-Costa et al., 2005).
These oocytes are arrested in prophase of the first meiotic division and are each surrounded by flattened pre-granulosa cells to form a structure called a primordial follicle [1].
The ultrastructural changes in the ovarian tissue after vitrification and 24 h culture were evaluated by assessing the structures of oocytes, granulosa cells and stromal cells separately.
During follicular maturation the germinal disc is closely associated with its overlying granulosa cells (GCs) and forms a structure called the germinal disc region (GDR).
The evidence that these structures give rise to granulosa cells came from early observations that rete ovarii can have a close association with oocytes (110, 111).
The oocytes and granulosa cells were considered as intact if all the structures were undamaged.
The ampullae (part of the oviduct) were tore using needles to release the super-ovulated oocyte structures that include the germ-cell surrounded by layers of granulosa cells.
These unassembled oocytes are present directly adjacent to one another in nest structures which are surrounded by somatic cells (i.e. precursor granulosa cells) [3], [4], [5], [6], [7], [9].
v) Atretic follicles: had abnormal structures such as inspissated follicular fluid, degenerated egg, disorganized and thickened granulosa layers or filled with organizing fibrinous material in the antrum.
Expression of the MISIIR has been reported to be restricted to mesenchymal cells surrounding the Mullerian duct during embryogenesis, tubular and follicular structures of fetal gonads, Sertoli and Leydig cells of adult testis, and granulosa cells of adult ovary [36], [37], [38], [39].
