Localization of hematopoietic cells in the bullfrog (Lithobates catesbeianus)

Abstract

Amphibians represent the first phylogenetic group to possess hematopoietic bone marrow. However, adult amphibian hematopoiesis has only been described in a few species and with conflicting data. Bone marrow, kidney, spleen, liver, gut, stomach, lung, tegument, and heart were therefore collected from adult Lithobates catesbeianus and investigated by light microscopy and immunohistochemical methods under confocal laser microscopy. Our study demonstrated active hematopoiesis in the bone marrow of vertebrae, femur, and fingers and in the kidney, but no hematopoietic activity inside other organs including the spleen and liver. Blood cells were identified as a heterogeneous cell population constituted by heterophils, basophils, eosinophils, monocytes, erythrocytic cells, lymphocytes, and their precursors. Cellular islets of the thrombocytic lineage occurred near sinusoids of the bone marrow. Antibodies against CD34, CD117, stem cell antigen, erythropoietin receptor, and the receptor for granulocyte colony-stimulating factor identified some cell populations, and some circulating immature cells were seen in the bloodstream. Thus, on the basis of these phylogenetic features, we propose that L. catesbeianus can be used as an important model for hematopoietic studies, since this anuran exhibits hematopoiesis characteristics both of lower vertebrates (renal hematopoiesis) and of higher vertebrates (bone marrow hematopoiesis).

Protection from UV light is an evolutionarily conserved feature of the haematopoietic niche

“…Interestingly, some mammals have genetically programmed melanocytes in the spleen 18 , and these melanocytes might represent an evolutionary remnant of the melanocyte umbrella we discovered in zebrafish. Some frog species such as certain Rana species exhibit shifting sites of haematopoiesis in adulthood with the bone marrow serving as the main and the liver as a minor hematopoietic site 19,20 . In addition, seasonal variation can be observed in these species, with the liver being more hematopoietic during the winter and the bone marrow during the summer 21 , which might reflect an adaption to changing UV levels.…”

Microanatomy of the digestive system of Supachai's caecilian,Ichthyophis supachaiiTaylor, 1960 (Amphibia: Gymnophiona)

“…This cell polarity is related to functional compartmentalization of the hepatocytes in the way that bile is secreted into bile canaliculi at the apical region, while bile acids, glucose, amino acids and plasma proteins are transported between the hepatocytes and sinusoids at the basal region of the hepatocytes (Mescher 2013). However, some adult anurans are devoid of the haematopoietic tissues in this organ (de Abreu Manso et al 2009;Akiyoshi and Inoue 2012). However, some adult anurans are devoid of the haematopoietic tissues in this organ (de Abreu Manso et al 2009;Akiyoshi and Inoue 2012).…”

Amphibian macrophage development and antiviral defenses

“…Immunohistological studies of the adult American bullfrog ( Rana catesbeianus ) have revealed the presence of active hematopoiesis within the vertebrae, femur and finger bone marrow as well as in their kidneys, but not in spleen, liver, gastrointestinal system, lungs tegument and heart tissues (de Abreu Manso et al, 2009). Unlike salamanders, there is no evidence of hematopoietic activity within the spleen and liver tissues of this species.…”

“…Unlike salamanders, there is no evidence of hematopoietic activity within the spleen and liver tissues of this species. Moreover, bone marrow and kidney HSCs of L. catesbeianus serve as precursors to heterophils, basophils, eosinophils, monocytes, erythrocytes and lymphocytes (de Abreu Manso et al, 2009). These observations are interesting since they indicate that the bullfrogs hematopoiesis takes place not only in the kidney, as in some anuran tadpoles (discussed above) and bony fish, but also in the bone marrow, similar to endothermic vertebrates.…”