ISOLATION AND CHARACTERIZATION OF CANINE ADVANCED PREANTRAL AND EARLYANTRAL FOLLICLES

This study was designed to develop preantral follicle isolation and cl assification protocols for the domestic dog as a model for endangered canids. Ovary donors were grouped by age, size, breed purity, ovary we ight and ovary status. Ovaries were randomly assigned to 1 of 3 digest ion protocols: A) digestion and follicle isolation on the day of spayi ng; B) storage at 4 degrees C for 18 to 24 h prior to digestion and fo llicle isolation; C) digestion on the day of spaying, then incubation at 4 degrees C for 18 h prior to follicle isolation. Minced tissue was placed in a collagenase/DNase solution at 37 degrees C for 1 h. Folli cles were classified by oocyte size and opaqueness and by size and app earance of the granulosa cell layers. Preantral follicles contained sm all, pale oocytes. Preantral follicles containing grown oocytes with d ense cytoplasmic lipid were designated as advanced preantral. Only adv anced preantral and early antral follicles were examined and classifie d further. Group 1 follicles had incomplete or absent granulosa layers , Group 2 follicles had several intact granulosa layers, while Group 3 were vesicular (early antral) follicles. Misshapen or pale grown oocy tes were classified as degenerated. The percentage of intact germinal vesicles (GV) was recorded for each Group. Digestion Protocol B produc ed the lowest percentage of degenerated follicles (P < 0.01). Prepuber tal donors had fewer (P < 0.01) follicles in each Group and more (P < 0.001) degenerated follicles than older bitches. Larger ovaries yielde d the highest total number of follicles (P < 0.05). Ovary status did n ot affect follicle yield. Oocytes from Group 1 follicles had fewer int act GVs than those from Group 2 or Group 3 (P < 0.0001). These finding s provide an opportunity for quantitative studies of the factors regul ating folliculogenesis in the domestic dog as a model for endangered c anids. (C) 1998 by Elsevier Science Inc.