Hypertrophy now takes place, the wall becomes much thickened and folded, and a growth of cells takes place from the wall into the cavity of the follicle, the sharply marked boundary of the wall is lost, and the long protoplasmic processes of the cells within the cavity are continuous with the cells of the wall.
The vessels of the wall now become enlarged and increased in number. Hypertrophy is no longer evident; the tissue is denser and shrunken, and the whole structure is reduced in size. Gradually the cavity of the follicle is also reduced in size, and the tissue contained therein becomes denser until it is hardly to be distinguished from that composing the wall.
Finally the whole of the cellular remains of the follicle consist of a comparatively small mass of cells with no trace of the follicle wall and no central cavity, a nearly solid mass of tissue, in the midst of which a few blood vessels run. The cells which compose this mass now scarcely differ from the ovarian stroma cells ; they have gradually undergone the change, and instead of branched cells they now appear as polyhedral cells or multinucleated polyhedral protoplasmic masses with intermediate finely branched connective tissue elements bounding them.
This structure is surrounded by a layer of fine nucleated fibres ; but soon these disappear, and the remains of the follicle are no longer distinguishable from the rest of the ovarian stroma.
Throughout, no trace of a blood clot within the follicle was seen, and therein these ruptured follicles differ from what is usually described as a normal ruptured follicle in the human female. This difference between two animals, both of which undergo menstruation, is remarkable and worthy of special attention.
I have some reason to believe the difference may be due to the presence or absence of the breeding season in monkeys, and to periods in the human female, which are in the one case favourable, and in the other case not favourable, to conception.
If this be true, the period, of the human female which is unfavourable to conception would be comparable to the non-breeding season of monkeys, and the period favourable to conception with the breeding season of monkeys.
It is not maintained that among civilised peoples at the present day there are definite breeding and non-breeding times, but the comparison is in harmony with the view that at one period of its existence the human species had a special breeding season.
