Effect of the Variations of Female Sex Hormones during the Menstrual Cycle upon Serum Somatomedin and Growth-Promoting Activity

Abstract

Serum growth-promoting activity measured upon lymphocytes, sulfation activity and radioimmunoassayable somatomedin C (Sm-C) levels were measured in sera from women during the menstrual cycle. The data showed that: (1) estradiol, progesterone, LH or FSH added in vitro do not incrase the ³H-thymidine uptake into lymphocytes; (2) the serum thymidine activity decreases during the luteal stage of the cycle, and is negatively correlated with the progesterone levels; (3) the sulfation factor and Sm-C levels do not have significant variations during the menstrual cycle, and (4) the GH maximum values are attained during the luteal stage.