Ontogeny and evolution of the sound-generating structures in the infraorder Delphinida (Odontoceti: Delphinida)

The ontogeny of the structures involved in sound generation and modulation in dolphins was investigated through a comparison of the soft nasal structures of foetal, perinatal, neonatal and adult specimens of Pontoporiidae, Phocoenidae and Delphinidae. Foetal samples were sectioned at 10 µm in the saggital and coronal planes, and stained for histological examination. Computed tomography and magentic resonance imaging scan series were combined with new data to represent the ontogenetic stages of the three groups. The images were analysed in 3D-Slicer to characterize the general head topography. The origins of the melon and the vestibular air sac were detected between Carnegie stages C16 and F22. The three groups analysed showed distinct formation of the nasal plug and nasal plug muscles, mainly with regard to the loss of fat pathways (or their maintenance in Pontoporiidae) and the development of the nasal plug muscles on both sides (during perinatal development of Phocoenidae) or just on the left side (during postnatal development in Delphinidae). Broadband vocalizing delphinidans might have evolved under heterochronic events acting on the formation of sound-generating structures such as the rostrum and vestibular air sacs, and on the transformation of the branches of the melon, probably leading to a reduced directionality of the sonar beam.

MRI to determine the chronological age of Ghanaian footballers

Background. The chronological age of the ordinary Ghanaian has often been difficult to verify as registration at birth is not compulsory. Consequently, an accurate method of age determination is needed in competitive age-restricted sports.Objective. To evaluate the age of Ghanaian soccer players who are aspiring to play for the national under-17 (U17) team, using the degree of fusion of the distal radius on magentic resonance imaging (MRI) and comparing it with the Fédération Internationale de Football Association (FIFA) MRI grading.Methods. MRI scans of the left wrists of 86 players aspiring to play for the national U17 football team were recruited for the study during a ‘justify your inclusion tournament’ organised by the Ghana Football Association between June and August 2012. The study was conducted in a diagnostic centre in Accra using a 0.35T MRI scanner. The images were analysed using the previously published FIFA grading system.Results. The mean chronological age of the players was 15.4 years (standard deviation ±0.7; range 12 - 17). The study showed that 43.0% of the MRI images were grade 6 (≥17 years) in relation to the degree of fusion of the distal radius, and 93.0% of the grade 6 players were aged 15 - 16 years chronologically. There was no significant correlation between the chronological age and the degree of fusion (r=0.075; p=0.493).Conclusion. Ghanaian U17 soccer players seem to be more biologically mature than a normative population of the same age category. The lack of correlation between age category and degree of fusion supports the suspicion that most Ghanaian players may not know their true age.

MRI to determine the chronological age of Ghanaian footballers

Background. The chronological age of the ordinary Ghanaian has often been difficult to verify as registration at birth is not compulsory. Consequently, an accurate method of age determination is needed in competitive age-restricted sports.Objective. To evaluate the age of Ghanaian soccer players who are aspiring to play for the national under-17 (U17) team, using the degree of fusion of the distal radius on magentic resonance imaging (MRI) and comparing it with the Fédération Internationale de Football Association (FIFA) MRI grading.Methods. MRI scans of the left wrists of 86 players aspiring to play for the national U17 football team were recruited for the study during a ‘justify your inclusion tournament’ organised by the Ghana Football Association between June and August 2012. The study was conducted in a diagnostic centre in Accra using a 0.35T MRI scanner. The images were analysed using the previously published FIFA grading system.Results. The mean chronological age of the players was 15.4 years (standard deviation ±0.7; range 12 - 17). The study showed that 43.0% of the MRI images were grade 6 (≥17 years) in relation to the degree of fusion of the distal radius, and 93.0% of the grade 6 players were aged 15 - 16 years chronologically. There was no significant correlation between the chronological age and the degree of fusion (r=0.075; p=0.493).Conclusion. Ghanaian U17 soccer players seem to be more biologically mature than a normative population of the same age category. The lack of correlation between age category and degree of fusion supports the suspicion that most Ghanaian players may not know their true age.