Time course of quantitative morphological changes of the autophagic-lysosomal compartment of murine seminal vesicle epithelial cells under the influence of vinblastine.

Changes of the autophagic-lysosomal compartment (ALC) of the murine seminal vesicle epithelial cells were monitored by electron microscopic morphometry during 36 h following a single 10 mg/kg bw dose of vinblastine sulfate (VBL), a widely used tool to cause an accumulation of the autophagic vacuoles (AVs). Three morphologically distinct subcompartments of the ALC, i.e. early autophagic vacuoles (AV1) being presumably prelysosomal autophagosomes, advanced AVs (AV2) containing material under degradation and dense bodies (DB) were defined. The ALC and its subcompartments expanded after VBL in a two-phase reaction. The first subcompartments to react significantly were AV1 and AV2 (at 30 min) followed by DBs with a 30 min delay. The ALC then ceased to grow until the 90th min when a second expansion phase started peaking around 8 h with a cytoplasmic volume fraction 15 times larger than in the untreated control. This second growth was entirely brought about by the expansion of the two AV subcompartments. After 8 h the volume fraction of both AV1 and AV2 decreased to cause a gradual regression of the ALC. AV1, however, already ceased to expand as early as after 6 h, i.e. during the last 2 h of the expansion phase of the ALC. Comparison of this time curve with the one we previously measured in mouse liver shows considerable differences between the two cell types. The growth curves of the AV subcompartments in our experiment along with others' kinetic data obtained in steady state cells not treated with VBL show that segregation (= formation of AV1) is possibly stimulated by VBL in our system.