Comparative Analysis of Histological Changes in Ussurian Bullhead, Leiocassis ussuriensis, and Korean Bullhead, Pseudobagrus fulvidraco, in the Early Period of Growth

Abstract

The histological changes in the Ussurian bullhead, Leiocassis ussuriensis, and the Korean bullhead, Pseudobagrus fulvidevrepaco, were observed during the early period of growth. The retinas size of both species increased in the 9 days post-hatching (DPH) (p<0.05). In the just-hatched Ussurian bullhead, the retina already consisted of six layers: the epithelial layer, ganglion cell layer, inner nuclear layer, inner plexiform layer, outer limiting membrane layer, and rod and cone layer. The Korean bullhead had the same components. At 50 DPH, the thickness of the retina was 538.0±7.19 μm in the Ussurian bullhead and 558.9±9.44 μm in the Korean bullhead. The relative thickness of each layer of the retina did not differ significantly in the two species. Although the growth of the Korean bullhead’s retina was faster, the relative thickness of each layer in the retina did not change during early development. After hatching, some parts of the tissue gradually became denser. Immediately after hatching, the kidney and midgut epithelium of the Ussurian bullhead and Korean bullhead were already formed and grew gradually thereafter. From 0 DPH to 30 DPH, the nuclear height in the midgut epithelium did not differ significantly between the two species, but at 50 DPH, it was 11.4±2.45 μm in the Korean bullhead and 9.9± 2.13 μm in the Ussurian bullhead. During the experimental period, the major axes, minor axes, surface areas, and volumes of the proximal tubule cells in the kidney did not differ significantly between the two species. Thus, the early histological development of the Ussurian bullhead is similar to that of the Korean bullhead.

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“…However, thickness of layer shows difference in this study comparison to other species. Based on the these results of this study and other researches with the fundamental functions of the retinal co mponents, that were infered the rates of change in the fish ret inal co mponents are related to their physiology and ecology in the early days of their development (Goo, Gil, & Park, 2013). For examp le, it fish that lives in dark environ ment like bottom of the river has thin RCL, or lives in light environ ment fish has thick RCL more than dark environ ment fish because RCL has substantial photoreceptors, rhodopsin and iodopsin.…”

“…For examp le, it fish that lives in dark environ ment like bottom of the river has thin RCL, or lives in light environ ment fish has thick RCL more than dark environ ment fish because RCL has substantial photoreceptors, rhodopsin and iodopsin. The fish like the dark environment, mud loach, cyprinid loach, showed a thin RCL at the development of the early retina and tendency to become thicker gradually (Han et al, 2013;Goo et al, 2013).…”