Mechanism of granulosa cell death during follicular atresia depends on follicular size.
Changes in granulosa cell lysosomal and mitochondrial functions in relation to follicular size and to the stage of atresia were studied by fluorescent emission spectra and intensity using flow cytometry. Antral follicles were grouped by size in two groups: small, 3-6 mm and large, >6mm in diameter, and classified into three stages of atresia: non-atretic, initially atretic and advanced atretic. Differences in Rhodamine 123 (Rh123) and Acridine Orange (AO) fluorescent intensity indicated that changes in mitochondrial function are the primary mechanism of granulosa cell death in atretic follicles 3-6 mm in diameter, while its role in granulosa cell death in >6 mm atretic follicles seemed to be less important. However, modifications in lysosomal function (shown by a decrease in fluorometric intensity of AO incubated granulosa cells) were mainly associated with cell death in large atretic follicles. Our results support the hypothesis that the pathway of granulosa cell death during follicular atresia depends on the state of energy metabolism or on the production of hypoxic conditions related to follicular size. Changes in mitochondrial membrane potential and production of permeability transition pores were the main changes found in small follicles, while lysosomal function destabilization seemed to be the major cause of granulosa cell death during atresia in large follicles.
Alonso-Pozos
Israel
I
Departamento de Producción Agrícola y Animal, Laboratorio de Bioquímica de la Reproducción, Universidad Autónoma Metropolitana, Unidad Xochimilco, Calzada del Hueso 1100, Col. Villa Quietud, Delegación Coyocán, México 04960, Mexico DF.
Rosales-Torres
Ana Maria
AM
Avalos-Rodríguez
Alejandro
A
Vergara-Onofre
Marcela
M
Rosado-García
Adolfo
A
D000165:Acridine Orange; D000818:Animals; D016923:Cell Death; D005260:Female; D005434:Flow Cytometry; D005456:Fluorescent Dyes; D005496:Follicular Atresia; D006107:Granulosa Cells / Q000502:physiology* / Q000648:ultrastructure; D008247:Lysosomes / Q000502:physiology; D008928:Mitochondria / Q000502:physiology; D006080:Ovarian Follicle / Q000033:anatomy & histology*; D020112:Rhodamine 123; D012756:Sheep; D013050:Spectrometry, Fluorescence
D005456:Fluorescent Dyes; D020112:Rhodamine 123; D000165:Acridine Orange