Conjoined twins
Keywords: conjoined, fetus, monster, bovine
The first image shows conjoined Holstein twins. An accurate description of this case would be: Conjoined, thoraco/omphalocopagus (joined at the thorax and umbilicus), monencephalus (one head) asymmetric (one fetus larger or distinctly different from the other) tetrapus (four feet) twins. Note: [-pus fr. Greek "pous" meaning "foot"].
The breeding date showed that this was a pregnancy approx. 8 months in duration. Yet, the larger of the two fetuses appeared to be about 6.5 months. This suggesting growth retardation of the larger conceptus.
Note:
Conjoined twins are named according to the section of the body where they are joined. Then the suffix "pagus" (fr. Gk pagos meaning “fixed”) is added. Parapagus is the most extreme form of conjoining where the notocords (the earlier axial support of the body) develop in close approximation, hence the use of the term "para" (fr. the same word in Gk meaning “beside or next to”). Less extreme forms are pygo- (tail), thoraco- , rachi- (fr. Gk rachis meaning "spine"), omphalo- and ischio- (fr. Gk iskion meaning “hip”). Other terms are added for greater accuracy.
As described in detail elsewhere in LORI, conjoined twins are invariably of the same gender and arise from a late division of a single conceptus, when the primitive streak is already forming. Usually this means that conjoined twins share a single amnion within a single chorion. Unfortunately this interesting phenomenon is seldom recorded in veterinary medicine, probably because the surgeon is preoccupied in delivering the conjoined twins by Cesarean section. Those who encounter conjoined twins are encouraged to examine and photograph their fetal membranes carefully and to forward those results to this author for possible inclusion in LORI.
Although one would presume that conjoined twins must always delivered by Cesarean section, this is not necessarily so; several cases of vaginal births of live, conjoined twins have been reported in humans and at least one in a grey whale. In quadrupeds like domestic animals, it may be possible for premature conjoined twins to be born per vagina but the author is unaware of natural delivery of conjoined twins at term.
This image below (38 years old!) shows a set of conjoined, thoraco/omphalocopagus twins but unlike those in the first image, these are symmetrical in nature. Read elsewhere in LORI how these twins are usually mirror images of one another, often with situs inversus of the internal organs.
Image size: 1024 x 654 px
The fetuses in the image below could be described as bicephalus and bicaudate, parapagus conjoined twins.
Image size: 1000 x 657 px.
As mentioned in the first paragraph, parapagus is the most extreme form of conjoining where the notocords of each embryo develop in close approximation.
Another entry in LORI illustrates an even more extreme degree of fusion than those shown here: a janusceps (janisceps) fetus.
