Ovogenesis during sexual maturity as elucidated by experimental methods. 1

Abstract

It has been repeatedly claimed that ovogenesis continues during sexual maturity but the evidence so far has not been considered entirely conclusive. On this account the more popular view among morphologists today is that ovogenesis in mammals ceases before puberty. The primary ovocytes contained in the mature ovary are not thought to be newly formed but simply stored there for later use.

The chief reason that a demonstration of post-pubertal ovogenesis has been so difficult is on account of the fact that the process in normal mature ovaries is much retarded and easily overlooked.

Recently my attention to this problem has been attracted by studying a series of ovaries from guinea pigs, in which the thyroids have been treated with radium emanation. Some of these ovaries had their germinal epithelium so much activated that all stages in post-pubertal ovogenesis could be seen and demonstrated almost as well as in young immature ovaries. By concentrating attention on this point I was later able to observe the activation of the germinal epithelium by other factors. Every factor that increases the congestion and the blood supply in the ovary seems to produce such an activatio'n. Injections of cystic fluid and of other glandular extracts may produce this effect.

This experimental stimulation of post-pubertal ovogenesis led me to study a large number of ovaries from normal guinea pigs at different life periods as well as from embryos and from the pregnant female. From this study a number of points of importance have been derived.

There is a continuous process of ovogenesis from the time of the gonadal differentiation in the embryos up to the time of cessation of sexual activity in the older female. This process decreases in activity with progressive age and almost ceases in the old female.