Anatomical description and morphometry of the skeleton of the common marmoset (Callithrix jacchus).

Callithrix jacchus (common marmoset) is regularly used in biomedical research, including for studies involving the skeleton. To support these studies, skeletons of healthy animals that had been euthanized for reasons not interfering with skeletal anatomy were prepared. The marmoset dental formula 2I-1C-3P-2M of each oral quadrant is atypical for New World monkeys which commonly possess a third molar. Seven cervical, 12-13 thoracic, 7-6 lumbar, 2-3 sacral and 26-29 caudal vertebrae are present, the thoracolumbar region always comprising 19 vertebrae. A sigmoid clavicle connects the scapula with the manubrium of the sternum. Depending on the number of thoracic vertebrae, 4-5 sternebrae are located between the manubrium and xiphoid process. Wide interosseous spaces separate the radius from the ulna, and the tibia from the fibula. A small sesamoid bone is inserted in the m. abductor digiti primi longus at the medial border of the carpus, a pair of ovoid sesamoid bones is located at the palmar/plantar sides of the trochleae of each metapodial bone, and round fabellae articulate with the proximal surfaces of the femoral condyles. Male marmosets possess a small penile bone. Both the front and hind feet have five digits. The hallux possesses a flat nail, whereas all other digits present curved claws. Interestingly, a central bone is present in both the carpus and tarsus. This study provides a description and detailed illustrations of the skeleton of the common marmoset as an anatomical guide for further biomedical research.

Distribution of the lingual lymphoid tissue in domestic ruminants.

The distribution and organisation of the intralingual lymphoid tissue was studied in sheep, goat and cattle. For each species, the tongues of two animals were harvested and divided in sample blocks extending over the total surface of the tongue. With 2.5 mm intervals, ten serial histological sections were made for conventional histological staining (haematoxylin-eosin, Van Gieson, Masson's trichrome) and immunohistochemical staining of lymphoid cells (anti-CD3, anti-CD21, anti-CD45). Lymphocytes were scattered in the subepithelial propria-submucosa and in the connective tissue cores of the lingual papillae. The connective tissue cores of fungiform papillae, including those located on the lingual apex, and vallate papillae showed relatively more lymphocytes than the propria-submucosa. Lymphoid cell aggregations were even more abundant beneath the grooves surrounding the vallate papillae in small ruminants. In cattle, a well-organised lingual tonsil was additionally found at the root of the tongue. CD3-positive lymphocytes were observed in all species examined. CD21-positive lymphocytes were numerous in the lymphoid nodules of the bovine lingual tonsil but very scarce in the ovine and caprine tongues. Therefore, the lymphoid cell aggregations in the tongues of small ruminants should not be referred to by the term 'lingual tonsil'.