FORM AND FUNCTION OF LACUNAE IN THE OVARY OF THE LAYING HEN

Background: Spontaneous atresia of large, yolky, ovarian follicles occ urs in the chicken and in other species when the stimulus for ovulatio n ceases. This means that as much as 40 ml of yolk must be resorbed by the ovary if normal ovarian morphology is to be regained. This study examines the process of yolk resorption in the ovarian stroma followin g bursting atresia. Method: Light, transmission, and scanning electron microscopy were used to study the morphology of lacuna spaces and the ir changes in ovaries of broiler and layer breeds of domestic chicken, both in actively laying birds and in birds undergoing spontaneous or induced follicular atresia. A comparative study was made of the ultras tructural differences between lacuna-lining cells, blood-vessel endoth elium, and germinal epithelium of the ovary. Results: Transformation o f lacuna-lining cells and peritoneal cells into macrophages occurred a fter bursting atresia and exposure of these cells to released yolk. Co mplete atresia of large yolky follicles occurred very quickly. Conclus ion: The resorption of this large volume of yolk, at least in part, se ems to be mediated by the transformed lacuna-lining cells. (C) Wiley-L iss, Inc.