Veterinary obstetrics, including the diseases of breeding animals and of the new-born . ^ is apparently the most common cause ofextra-uterine gestation and, in all probability, accounts for themajority of cases of this character. Tubal gestation is morereadily understood than other forms. Any defect in the tube,which might cause the arrest of the ovum during its passagethrough it, would naturally result in the attachment and devel-opment of the embryo at that point. In multiparous animals, ifone of the earliest ova should become arrested during its Fig. 8i. Extra-uterine pregnancy. S
Veterinary obstetrics, including the diseases of breeding animals and of the new-born . ^ is apparently the most common cause ofextra-uterine gestation and, in all probability, accounts for themajority of cases of this character. Tubal gestation is morereadily understood than other forms. Any defect in the tube,which might cause the arrest of the ovum during its passagethrough it, would naturally result in the attachment and devel-opment of the embryo at that point. In multiparous animals, ifone of the earliest ova should become arrested during its Fig. 8i. Extra-uterine pregnancy. Swine. Showing 2 fetuses closelyadherent to each other and intimately invested b} membranes. all those on the ovarian side of it would alike become halted intheir migration. Consequently, a series of tubal embryos mightbe formed, which apparently occurs sometimes in domestic Extra-Uterine Pregnancy 417 animals, especiallj in the sow, and leads eventually to the exist-ence of a group of two or more extra-uterine fetuses, as shownin Fig. 81. The cause of the arrest in the migration of the ovum may be afolding in the tube or disease or injury of the mucous tendency of tubal pregnanc3 in animals is for the develop-ment to go forward, in a quasi-normal manner, up to that periodwhen the volume of the fetus and its membranes becomes sogreat that the tube is no longer capable of accommodating the thin walls of the tube rupture and the fetus orfetuses, with part or all the membranes, pass out into the perito-neal cavity. This rupture and
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectveterinaryobstetrics
