Histological Studies on Some Organs of Two Male Dealfishes, Trachipterus ishikawae, Caught on the Beach of Shirahama, Wakayama Prefecture, Pacific Coast of Japan

Abstract

The testis, thyroid, kidney, exocrine pancreas, endocrine pancreas (=Brockmann body), spleen and liver of two dealfishes, Trachipterus ishikawae, collected on the beach of Shirahama, Wakayama Prefecture, Pacific coast of Honshu, Japan, were examined histologically. The specimens measured 2.30 m (specimen A) and 1.65 m (specimen B) in total length. The testicular lobes were atrophied and sclerotized, having the appearance of an aggregation of numerous protuberances (or spherules), each spherule corresponding to a lobule containing a number of cysts, although some of the latter had collapsed and/or merged with each other. Each cyst contained sperms and spermatids, relict sperms being found in the spermiduct. The thyroid gland, an amorphously soft body, located dorsally on the ventral aorta and its afferent branchial arteries, was composed of many variously-sized follicles. Each follicle comprised a large amount of smooth colloid, surrounded by a flat epithelium consisting of cubic cells. The overall condition indicated an inactive state. In the kidney, a great deal of stromatous tissue, including AF positive lipid grains, and a small number of glomeruli were apparent. In both specimens, the thread-like loose connective tissue comprising the exocrine pancreas attached to and running parallel with the liver, stomach, Brockmann body and spleen, were composed of acini with zymogen-rich pyramidal cells. Details of cell types in the Brockmann body were difficult to determine. Fatty deposits were absent from the liver of specimen A, which was characterized by rich stromatous tissue and dilated sinusoids. However, rich fatty deposits were found in several portions of the liver of specimen B. Well-developed stromatous tissue and nodules of red- and white pulps were recognized. It was concluded that the two specimens were spent and debilitated males.