Conjoined twins in a rhesus monkey (Macaca mulatta)

Abstract

Conjoined twinning is an extremely rare occurrence among human and nonhuman primates. The current report describes a case of minimally conjoined omphalopagus rhesus monkey twins that were observed in the breeding colony at the California Regional Primate Research Center. The full-term nonviable male twins were morphologically normal and united in the umbilical region, involving the liver, xiphoid, umbilicus, body wall, and skin. The umbilical cords were separate, but closely aligned, within an ensheathing amnion; each cord contained two arteries and a vein. The closely associated cords were centrally inserted on a large bidiscoid placenta. There were no gross or histologic abnormalities in the viscera, with the exception of enlargement of the left central liver lobes, which constituted the area of attachment. The cause of death was attributed to asphyxia and trauma experienced during parturition.

Conjoined twins: A worldwide collaborative epidemiological study of the International Clearinghouse for Birth Defects Surveillance and Research

“…Prevalence, although variable, has been estimated to be 1 in 50,000 to 1 in 100,000 births [Hanson, 1975; Källén and Rybo, 1978; Edmonds and Layde, 1982; Viljoen et al, 1983; Castilla et al, 1988; ICBDMS, 1991; Rees et al, 1993; Martínez‐Frías et al, 2009]. CT is not restricted to humans; it has been reported in fish, reptiles, birds, primates, and other mammals [Levin et al, 1996; Canfield et al, 2000]. The first aspect to consider is as stated by Weber and Sebire [2010] that “CT is itself a malformation and is associated with secondary changes related to abnormal conjoined organs and superimposed effects of abnormal hemodynamics.” Proposed mechanisms of the defect cannot explain the alterations in the normal developmental process, by which a pair of monozygotic (MZ) twins do not fully separate from each other and continue their normal embryologic development.…”

Generation and Breeding of EGFP-Transgenic Marmoset Monkeys: Cell Chimerism and Implications for Disease Modeling

“…Therefore, it would be highly expedient to carefully test whether (blood) cell chimerism can also occur in macaques. This is important considering that the limited information on the placental development in macaque twin pregnancies does not exclude that placental fusion, with the possibility of an exchange of hematopoietic stem cells, may also occur in macaques [90,91].…”

Conjoined twins—past, present, and future

“…The incidence of conjoined twins is reported from 1 in 50,000 to 1 in 100,000 births [3]. Conjoined twins have also been reported in animals such as sheep, cattle, horses, and cats [4,5]. Conjoined twinning is also observed in fruits and vegetables.…”