In the normal position of the reproductive organs the hymen has very rarely the appearance of a tense membrane; as a rule it is folded up, and becomes plainly manifest only when the genital organs are stretched. The margin of the hymeneal aperture, as a close examination shows, is sometimes sharp and regular, sometimes lobulated, with small congenital notches. These congenital notches are to be distinguished from the lacerations resulting from defloration by the fact that the former have a smooth border, which is of the same consistency as the general substance of the hymen. In some instances the border of the aperture in the hymen is beset with small, fine villi (villous hymen).
The common varieties of the hymen are thus classified by Maschka:
1. The annular hymen, in which the membrane when stretched is seen to have a rounded aperture, which may be central or eccentric; very often, indeed, the aperture is more toward the upper half of the hymen, in which case it is not always circular, but frequently rather ovoid in shape.
2. The semilunar or crescentic hymen, in which the aperture is eccentrically placed in the upper half of the membrane, in such a manner that the hymen exhibits a wide surface below the aperture, which surface narrows at either side as it passes upwards until it disappears, the two sides failing to reunite above the aperture.
3. The heart-shaped or cordiform hymen, the general shape of which may be circular, ovoid, or even semilunar, but in which from the middle of the upper or lower margin a three-cornered tongue projects across the aperture, which is thus given the form of the conventional heart of a pack of cards.
4. The infundibuliform hymen has the form of a small projecting funnel resembling in appearance the invaginated end of the finger of a glove.
Maschka refers also to the rare condition in which the hymen is sometimes said to be absent. As a matter of fact, however, in such cases, it is represented by a very narrow annular eminence, the genitals being in other respects normal. The smooth character of the eminence will serve to differentiate it from the remains of a destroyed hymen. Other rare forms are:
1. The imperforate hymen, an occlusive membrane, entirely blocking the vaginal orifice. In some cases, however, the hymen is not absolutely imperforate, a very small, punctiform aperture being present.
2. The cribriform hymen, a hymen which is “imperforate” in the sense that there is no opening of a size approaching the normal, but in which several minute apertures are present.
3. The septate, bridged or divided hymen (hymen bifenestratus, etc.), exhibits a strip of mucous membrane, most commonly running directly from before backward, occasionally, however, somewhat obliquely, across the aperture in the membrane, which is thus divided into two equal or unequal parts. In some instances the process that bridges the aperture of the hymen is expanded in the vertical plane to form a septum which projects for some distance into the vagina.