Dicephalous v. diprosopus sharks: record of a two-headed embryo of Galeus atlanticus and review of the literature

Symmetrical parapagus diprosopus: A comparative, computed tomographic, and pathoanatomical study of a new case in domestic pig

BACKGROUND

Parapagus diprosopus are conjoined twins characterized by craniofacial duplication and only one body, representing one of the rarest types of these twins. Their occurrence has been recorded in different species of vertebrates, including humans, but few cases have been studied in domestic pigs.

CASE

A pair of conjoined twin pigs was studied using x-rays, computed tomography, and necropsy. The abnormalities found were compared with those of the rare swine cases presented in the literature as well as with other species, and the different etiopathogenetic possibilities were addressed. The degree of duplication of the head bones decreased caudally, as did that of the structures of the central nervous system. In the two oral cavities, there was a complete cleft palate. All the cervical vertebrae and thoracic vertebrae up to T3 were partially duplicated. The heart and great vessels were normal, as were the other thoracic and abdominal organs.

CONCLUSIONS

The conjoined twin pigs of this study are a case of parapagus diprosopus tetraophthalmus triotus, presenting the same pattern of abnormalities of human diprosopus and that of other species. The scarcity of detailed studies on craniofacial duplication in pigs and the lack of a definitive explanation on the etiology and pathogenesis of conjoined twins shows the need for further research and the publication of more cases.

Symmetrical parapagus diprosopus tetrophthalmos in a bovine calf, with computed tomography imaging, and review of craniofacial duplications

Diprosopia, a congenital defect process also known as craniofacial duplication, is well-recognized in humans and has also been reported in numerous animal species. Here we describe a case of diprosopia in a live mixed-breed beef calf. We used computed tomography imaging to characterize internal and external abnormalities which, to our knowledge, have not been reported in any diprosopic veterinary species. Additional diagnostic tools included postmortem examination and histopathology. This case highlights distinct anatomic features associated with diprosopia and underscores the unique challenges associated with classifying and managing fetal malformations.

A rare case of partial skull and brain duplication in a hatchling Alligator mississippiensis

Errors in development occur in all vertebrates. When severe, these anomalies are lethal and frequently escape attention. In rare cases, animals with profound malformations are born and can provide a glimpse into structures and their respective function that would otherwise go unnoticed. A rare abnormality in a hatchling Alligator mississippiensis is described in which duplication of the skull, face, and brain was incomplete. The rostral skull, face, and associated forebrain, including the olfactory apparatus, were duplicated. However, the caudal skull and brainstem were not. These observations were made with advanced imaging using both computed tomography and magnetic resonance coupled with gross brain dissections. These abnormal features emphasize the complex and intertwined relationship between the development of the brain, face, and skull which are influenced by certain signaling molecules, possible gene mutation(s), and potential environmental factors.

Morphological abnormalities in seven American round ray specimens: A review of America's batomorph anomalies

Although morphological abnormalities in several rays and skate species around the American continents have frequently mentioned, their numbers are unknown. The present work record morphological abnormalities in four Urotrygonidae species. Two anophthalmic specimens were detected (Urotrygon microphthalmum and Urobatis halleri). Two individuals lacked caudal fins (Urobatis maculatus and Urotrygon chilensis). Two round rays showed incomplete fusion of the pectoral fin to the head (U. microphthalmum and U. chilensis). Vertebral compression and fusion were found in a 6-year-old female Urotrygon rogersi. In addition, 118 abnormal batomorph specimens were gathered from the available bibliography, spanning the last six decades (1959-2021). Amblyraja doellojuradoi was the species with the highest number of abnormalities (18). The most common anomaly was an incomplete fusion of the pectoral fin with the head. Since 2010, at least 30 anomalous batomorphs have been recorded every 5 years. Sixty-nine abnormal specimens occurred in the Northern Hemisphere (1.00-60.00 N). The Cortezian (Pacific) and Southeastern Brazil (Atlantic) marine ecoregions stood out with the highest number of these specimens. Mexico recorded 58 anomalous specimens, followed by Brazil (n = 36). Biological, abiotic and anthropogenic factors are probably the leading causes. However, additional studies are necessary to elucidate these speculations.

Living naked: first case of lack of skin-related structures in an elasmobranch, the blackmouth catshark (Galeus melastomus)

As far as is known, in this paper the first case of lacking of skin-related structures (epidermis, stratum laxum, dermal denticles and teeth) in a free-swimming elasmobranch, the blackmouth catshark, Galeus melastomus, is reported. The individual was caught by trawl in Sardinian waters (central-western Mediterranean) in July 2019 at a depth of 500 m. Although this kind of morphological abnormality is potentially fatal, the observations suggested that the specimen was in good health and well developed.