Pituitary enhancement of Wolffian lens regeneration in vitro: spatial and temporal requirements.

When irido-corneal complexes (ICC's) from eyes of adult newts (Notophthalmus viridescens) are cultured on top of pituitary glands they produce advanced lens regenerates in up to 90% of the cases (this report and Connelly et al., '73). To determine if the iris and pituitary gland must be in direct contact with each other in order to produce this enhancement of lens regeneration, ICC's were cultured next to pituitary glands or separated from them by a Nuclepore filter. Cultures behaved as ICC's cultured in the absence of the pituitary gland and produced few advanced lens regenerates. To determine how long the iris and pituitary must be in contact for the enhancement to occur, ICC's were explanted and 5, 10 or 15 days later pituitary glands were placed beneath the dorsal iris pupillary margin. There was a progressive decrease in the number of advanced lens regenerates formed in cultures receiving pituitary glands later than five days after initial explantation of the iris. The conclusions drawn from these experiments are that the iris and pituitary gland must be in extensive direct contact during the first five to ten days in culture in order for pronounced enhancement of lens regeneration to occur.