The X zone of the mouse adrenal cortex of the Swiss albino strain

The adrenal gland of the Swiss albino strain was investigated with particular reference to the X zone. The degeneration of the X zone in the male occurred concomitant with puberty. The unmated female possessed an X zone which gradually degenerated with age. First pregnancy gave a rapid disappearance of the zone. Gonadectomy preserved the X zone in both sexes, to decline with age. Hypophysectomy produced the classical sequelae, but injecting equine luteinizing hormone preserved the X zone. The X zone and its homologous/analogous representatives in various eutherian species differ from the pattern given in a common laboratory mouse. The difficulties are discussed.