Lymphomyeloid organs of amphibia. II. Vasculature in larval and adult Rana catesbeiana.

Abstract

AbstractThere were no lymphatic vessels and lymph nodes demonstrable in adult and larval Rana catesbeiana by a method that adequately demonstrated the same in mammals. Although the parenchymal arrangement in the lymphomyeloid organs is not exactly the same as in mammalian hemal nodes, nonetheless the vascular patterns of the lymph glands and jugular bodies are prima facie evidence that they function as blood‐filtering organs among other probable functions. The vascular pattern of the lymph gland is that of a rete mirabile, particularly a venous portal system, inasmuch as the afferent and efferent vessels are venous in character and interposed between them is a labyrinth of sinusoids. This is not the case, though, in the adult organs. The vascular pattern of the jugular bodies is very much like the spleen, viz., artery‐capillary‐sinusoid‐vein sequence. It is doubtful, however, if the propericardial and procoracoid bodies ever filter blood, because the smallest blood vessels in them are capillary in type Because of the absence of a well‐defined capsule in some parts of the propericardial body, similarly to lymphoid follicles, especially in the mammalian gastrointestinal tract, it is probable that it filters tissue fluid. The last two organs are apparently mainly blood cell‐forming organs. It is inferred from the vascular connections of the larval and the adult lymphomyeloid organs that they are not genetically related. This aspect was analyzed from earlier developmental data, but actual follow‐up of the larval organs to the adult stage is still in progress.