morphogenesis and ductal development of the prostatic complex of the guinea pig the morphogenesis of glandular architecture of the three lobes of prostate gland of the guinea pig lateral dorsal and coagulating gland was studied from 35 days gestation to 90 postnatal days epithelial ductal tubules of various lobes of the gland were microdissected after treatment by collagenase and displayed two dimensionally the number of ductal tips was counted and the volume of the ductal network was quantified using a graphic tablet the results show that the growth and ductal morphogenesis fall into two phases prenatal and postnatal the first outgrowth of prostatic buds begins at 35 days gestation gestational length is 65 days ductal growth and branching continues over the next 1520 days and by 55 days gestation approximately 60 79 and 71 of the adult number of ductal tips of the lateral and dorsal lobes and coagulating gland respectively are formed the figures increase to 89 84 and 106 respectively by birth there is little increase in number of ductal tips thereafter postnatal growth is accomplished mainly by elongation of existing ductal network with a little additional branching but with an increase in size volume of the tubules canalization of ductal tubules occurs prenatally in all lobes but postnatal functional cytodifferentiation takes a slightly different pace among them ductal morphogenesis of the guinea pig prostate gland differs significantly in timecourse from that of the mouse in which ductal development occurs mainly postnatally