Extra-uterine Gestation.

Extra-uterine Gestation.

It is rare in the domestic animals to find the fetus developed elsewhere than in the womb. The exceptional forms are those in which the sperm of the male, making its way through the womb and Fallopian tubes, impregnates the ovum prior to its escape, and in which the now vitalized and growing ovum, by reason of its gradually increasing size, becomes imprisoned and fails to escape into the womb. The arrest of the ovum may be in the substance of the ovary itself (ovarian pregnancy), in the Fallopian tube (tubal pregnancy), or when by its continuous enlargement it has ruptured its envelopes so that it escapes into the cavity of the abdomen, it may become attached to any part of the serous membrane and draw its nourishment directly from that (abdominal pregnancy). In all such cases there is an increase and enlargement of the capillary blood vessels at the point to which the embryo has attached itself so as to furnish the needful nutriment for the growing offspring.