In this study, ultrastructural changes on ovaries of Quinea pigs during postnatal development were investigated. The study population was consisted of 56 female guinea pigs which were divided into seven groups according to age; 1 days, 2, 4, 6, 12, 18 week and older than 18 weeks. Each group contained 8 Quinea pigs.

It was shown that surface epithelium cells of ovaries have the usual cytoplasmic constituents such as the Golgi complex, mitochondria. The basement membrane beneath the epithelium have been gradually increased in thickness.

By the time maturity has been reached, there has been a great increase in electron density in both the nucleus and cytoplasm of the surface cells. The background cytoplasm of surface epithelial cells was comprising highly electron dense and lipid inclusions.

One of the most striking changes occuring during development is the increasing lobulation of the epithelial cell nuclei.