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ThesisItem Open Access Preservability of bovine preantral follicles in situ(Department of Animal Reproduction, Gynaecology and Obstetrics, College of Veterinary and Animal Sciences, Mannuthy, 2008) Harinarayanan, P M; KAU; Vijayakumaran, VThe study was designed and conducted with the objectives of assessing: (1) efficiency of two different temperatures, media and duration of storage for short term preservation of bovine preantral follicles in situ and (2) efficiency of conventional vitrification (CV) and solid surface vitrification (SSV), for long term cryopreservation of bovine preantral follicles in situ. Ovaries of six freshly slaughtered adult crossbred cows were collected and transported to the laboratory within one hour in normal saline at room temperature. The ovarian cortex from both ovaries of each animal was separated, divided further into fifteen pieces. One hour after the slaughter a cortical piece was selected at random from each animal and fixed in Bouin’s fluid for histological processing later on (control). Twelve cortical pieces from each animal were randomly allotted for short term preservation, of which, six pieces each were placed in vials containing normal saline and remaining in Dulbecco’s phosphate buffered saline (DPBS). Three vials from normal saline group and DPBS group were stored at room temperature (25ºC) and the remaining three vials from each group were stored at refrigeration temperature (3-5ºC). One cortical piece was taken out, from each media, from both the storage temperatures, at four, eight and twelve hours of storage and fixed for histological analysis. The remaining two cortical pieces were further divided into smaller fragments of approximately 1mm3 size. The fragments from one piece were vitrified using conventional vitrification (CV) and the rest by solid surface vitrification (SSV) and stored in liquid nitrogen for ten days. The fragments were warmed and fixed after the storage period. The quality of preantral follicles in the fixed ovarian tissues was evaluated based on morphology in histological sections. The preantral follicles were counted, classified as primordial, primary and secondary. Storage at refrigeration temperature preserved the preantral follicles very much better than the storage at room temperature. The amount of normal preantral follicles reduced progressively with passage of time. Primordial follicles were better adapted to preservation than primary and secondary follicles. The preantral follicles were best preserved at refrigeration temperature up to four hours of storage. The morphologically normal preantral follicles in normal saline (55.17 %) and DPBS (56.17 %) at this temperature and storage period did not show significant difference from that of control (59 %). The primordial follicles were preserved in both normal saline (61.42 %) and DPBS (61.15 %) at refrigeration temperature up to four hours, at levels similar to control (62.63 %). However, only DPBS at refrigeration temperature could ideally preserve primary (51.13 % vs. 53.06 % in control) and secondary follicles (42.10 % vs. 48.83 % in control). The number of morphologically normal preantral follicles in situ was significantly reduced after both CV (25.5 %) and SSV (37.17 %). But, SSV was significantly better than CV for preserving the quality of preantral follicles. According to this study DPBS at refrigeration temperature is ideal for preserving all the three classes of bovine preantral follicles in situ up to four hours of storage. Though vitrification of bovine ovarian tissue could not preserve preantral follicles at ideal levels, SSV was found to be far superior to CV in preserving bovine preantral follicles in situ.