WEIGHTS OF CYCLIC AND PREGNANCY CORPORA LUTEA OF DAIRY COWS

Summary. The weights of 114 cyclic and 245 pregnancy corpora lutea have been compared and some sources of their variations assessed. It was found that the pregnancy corpus luteum (corpus luteum verum) was significantly heavier than the cyclic corpus luteum. Variations were found in the weights of corpora lutea vera due to the stage of gestation and to the season in which conception occurred. The corpus luteum verum increased in size until 2 to 3 months of gestation and then re- gressed until 4 to 6 months of gestation, remaining about this size until term. A similar pattern of growth and regression was followed at various weight levels according to the season in which conception occurred. Although no seasonal variation in weight was noted in cyclic corpora lutea, corpora lutea vera attained the greatest weights following conceptions during summer and the smallest weights were found following conceptions in winter.