Recent Progress in Hormone Research, Volume 26 covers the proceedings of the 27th annual meeting of the Laurentian Hormone Conference held at Mont Tremblant, Quebec, Canada on August 24-29, 1969. The book presents papers on the pituitary and gonadal hormones in women during spontaneous and induced ovulatory cycles; the mechanisms regulating the menstrual cycle in women; some physical and hydrodynamic properties of human FSH and LH; and the biological significance of the prostaglandins. The text also includes papers on thyroid peroxidase and thyroxine biosynthesis; the significance of circulating triiodothyronine; the multiple hormone interactions in the development of mammary gland in vitro; and the intranuclear metabolism of testosterone in the accessory organs of reproduction. Papers on the aspects of androgen-dependent events as studied by antiandrogens; the hormonal control of hepatic gluconeogenesis; and the control of fat cell development and lipid content are also encompassed. The book further encompasses papers on the properties of thymosin; the study of spermatogenesis and steroid metabolism in cultures of mammalian testes; and the role of ACTH on the metabolism of adrenal cell cultures.