File:CSIRO ScienceImage 2235 Fertilised Egg.jpg

English: Another mating and fertilization occur just after the young reaches the pouch but since the pouch is occupied for the eight months there is no room for another occupant during this period. The embryo derived from the mating, which takes place after birth assumes a resting phase (shown here) during suckling of the young in the pouch. It is about 0.25 mm diameter and remains this size for up to more than 200 days. If the young is lost from the pouch the resting embryo resumes development and another young results. Normally it resumes development when the young is about 7 months old and a newborn derived from it enters the pouch as soon as the first young permanently vacate it. Kangaroo research was carried out by CSIRO from the early 1960s to the late 1980s. The process of kangaroo reproduction was revealed for the first time by CSIRO researchers, G B Sharman and J H Calaby, providing a basis for significant research by universities and state departments from the late 1960s. A series of 13 images makes up this series DA1487, DA1497 to DA1507 and DA1509. Photograph: Ederic Slater