Ultrastructural preservation of ovarian cortical tissue cryopreserved in dimethylsulfoxide for subsequent transplantation into young female cancer patients

Cytotoxic therapy in young women with cancer may cause loss of ovarian function, and ovarian cryopreservation has been proposed as a means of preserving fertility. The objective of this study is to assess ultrastructural preservation of follicles in frozen-thawed ovarian cortical strips, previously cryopreserved using dimethylsulfoxide and a standard slow-cool/rapid-thaw protocol. Ovarian cortical strips (patients, n = 7) were thawed and fixed in glutaraldehyde for epoxy resin embedding electron microscopy according to conventional procedures. Oocytes were generally well preserved, on the basis of plasma-membrane integrity, uniformity of chromatin pattern, mitochondrial and rough endoplasmic reticulum (rER) cisternal integrity, and absence of cytoplasmic and intranuclear clear spaces. Frequently, rER cisternae were distended and intramitochondrial matrices lost. Granulosa cells showed somewhat variable preservation. Some were dark-staining; others exhibited washed-out cytoplasm containing damaged or artifactually expanded organelles. The consistently good preservation of oocytes and the good but more variable preservation of granulosa cells provides scientific validation of one component in the overall clinical procedure of attempting to reestablish fertility in young female patients after cytotoxic therapy for cancer.