title: Case of cephalothoracopagus conjoined twinning in an embryonic mouse.
abstract: BACKGROUND
  Cephalothoracopagus twinning is extremely rare, and it is characterized by fusion of the head and thorax, two separate spines, pelves, and fore- and hindlimbs.
  
  
  METHODS
  In this case study, we describe cephalothoracopagus twinning in an embryonic mouse displaying a large but exencephalic head, median facial cleft, a single eye, and a second hindbrain rotated roughly 90° from a second spinal cord. There is a bony connection joining the clavicles, resulting in merged asternal thoracic cavities containing two hearts and four lungs. The abdominal cavities contain double caudal digestive tract structures, but a single esophagus and stomach.
  
  
  CONCLUSIONS
  There are several proposed theories regarding the mechanism of spontaneous conjoined twinning; however, the specific mechanisms are still largely unknown. In this report, we highlight the morphological features in a murine example of cephalothoracopagus twinning, furthering our understanding of this rare occurrence while also demonstrating developmental morphogenesis consistent with that reported for human conjoined twins.
authors.affiliation: Department of Anatomy, Biochemistry and Physiology, John A. Burns School of Medicine, University of Hawaii, Honolulu, HI 96813, USA. hynd@hawaii.edu
authors.forename: Thomas E
authors.initials: TE
authors.lastname: Hynd
authors.forename: Cadie L
authors.initials: CL
authors.lastname: Buckley
authors.forename: Scott
authors.initials: S
authors.lastname: Lozanoff
mesh_terms: D000818:Animals; D006257:Head / Q000473:pathology*; D006652:Histological Techniques; D051379:Mice; D013909:Thorax / Q000473:pathology*; D014428:Twins, Conjoined / Q000473:pathology*