The ovaries of 40 cows, 20 with luteinized follicular cysts (Ifc) and 20 with corpora lutea periodica (clp), were collected at the Hannover slaughter house. Their h e a l tissues were classified into 5 developmental stages by histological examination. Twenty-five randomly selected large h e a l cells from each of two tissue regions of every Ifc and clp were measured for cell area, cell perimeter, nuclear area, and nuclear perimeter with a microscope morphometer. Additionally, the cytoplasmic area and the ratio of nuclear area to cytoplasmic area (1 : q, q = cytoplasmic area : nuclear area) were calculated.With respect to h e a l tissue development, the data of all variates determined in Ifc and clp showed characteristic profiles. The profiles of cell area, cell perimeter, cytoplasmic area, and the ratio 1 : q paralleled the h e a l cells' steroidogenic activity, as reported in the literature. The ratio 1 : q was the widest when the luteal tissue had reached its maximal development. Presumably it is an expression of the activity of large luteal cells. The large luteal cells of Ifc and clp showed no relevant differences as to the variates determined. The results are discussed with regard to the clinical significance of the lfc. Zusammenfassung Die groi3en Luteinzellen von Follikel-Lutein-Zysten und Corpora lutea periodica beim Rind. Eine zytometrische Studie Auf dem Schlachthof Hannover wurden die Ovarien von 20 Kuhen mit Follikel-Lutein-Zysten (FLZ) und von 20 Kuhen rnit Corpora lutea periodica (Clp) gesammelt. Aufgrund histologischer