THE EFFECTS OF IMPLANTING ADULT HYPOPHYSES INTO SEXUALLY IMMATURE FUNDULUS

¹ From the Thompson Biological Laboratory, Williams College and the Marine Biological Laboratory, Woods Hole, Mass.

Pituitary glands of adult Fundulus were implanted into the eyes of sexually immature animals. Of twenty-seven cases examined several weeks after operation the gonads of only four showed greater activity than did those of control animals.

In another series of experiments adult pituitary glands were implanted at three-day intervals into the peritoneal cavity of immature Fundulus. At the end of four weeks all twenty-four experimental animals of both sexes showed a high degree of gonadal stimulation. This was particularly notable in the males where large numbers of mature spermatozoa and pigmentation characteristic of the adult during the breeding season were produced. The success of this method of implantation, which continuously supplied the young individual with fresh gland material, indicates that the failure in most cases of the method employing intra-ocular implants was due to a failure of the implanted gland to establish itself successfully so that it provided an inadequate supply of gonad-stimulating substances to the host.

The precocious development of the gonads produced by implanting the adult pituitary gland strongly suggests that the normal development of the mature condition of the gonad in Fundulus is controlled by the pituitary gland.