The effect of locally administered prolactin on the respiratory activity of the mammary gland of rabbit at the corresponding stage to the alveolar formation.

It has been shown by numerous workers that prolactin participates in the mammary gland growth. Previously, we showed that prolactin induced alveolar formation when it was injected intraductally in the rabbit mammary gland having a moderately developed duct system with few alveoli in the histological study (Mizuno et al. , 1955)and in the study on the nucleic acids content(Mizuno and Naito, 1956). In this connection, it is of interest to investigate the effect of prolactin on the mammary respiratory activity at the corresponding stage to the alveolar formation.