| The methods of anatomy, histology, histo-chemistry, electron microscope were applied to study the morphology and development of the pro-nephron, head kidney, and the kidney in the southern catfish, Silurus meridionalis Chen from March, 2001 to March, 2002. The results are indicated as following.The two parts of head kidney are separated; and they aren't joined with kidney. The renal antennal region is separated and the middle and posterior parts are joined. Two strands of renal tissue exist at the back of gas bladder. In five kinds ofrenal shape of teleost, the southern catfish's belongs to type II - B. There are 2 to 9Stannius corpuscles in the renal back middle part. They are different in size.The renal tissue of adult fish includes nephron, collecting duct, meso-nephric duct, Lymphoid tissue and the endocrine tissue (stannius corpuscles). The nephron includes renal corpuscle and renal tubule. There are 3.8, 3.4 and 2.6 nephrones in every square millimeter in forepart, middle part, and posterior part of the kidney. The renal corpuscle is 66.5 um in diameter and is distributed in individual. It's the typical nephron of freshwater fishes. The capillary vessel of glomerulus is lacunary. They have clear basal membrane. Capillary vessels are connected with mesenteric cell. The epithelia of Bowman's copsule is simple pavement epithelium. The splanchnoderm cell is podcyte. Its processes cling to endothelial cell of capillary vessel, and there is a hole between proceses.The renal tubule consists of five distinct segments. The epithelia of renal tubule are monolayer, all of them have basal memberane. There are a lot of wandering cells in the renal tubule except neck segment. Neck segment cell is cubical epithelium. There are abundant brush border at the margo iiber of primary proximal segment and second proximal segment. The top of primary proximal segment cells has a PAS- positive zone where possess lots of electric dense matter and rough endoplasmic reticulum. The epithelia of distal segment and collecting segment have lots of mitochondria and infoldings of plasmalemma. The function of them isreabsorption of Na+ ion. Collecting ducts in deferent levels influx to meso-nephric duct.The Lymphoid tissue of kidney includes 6 kinds of cells: lymphocyte, plasma cell, monocyte, melano-macrophage, granulocyte and red cell. The granulocyte develops in lymphoid tissue. Development of granulocyte goes through five stages: myeloblast, progranulocyte, myelocyte, metamyelocyte, granulocyte. The glandalveolus of Stannius corpuscle is shaped in cord, and the glandular cell belongs toPAS-negative t2-cell.Head kidney consists of lymphocyte-aggregate region, granulocyte-aggregate region and endocrine tissue region. Its blood vessel includes artery, veins of head kidney and posterior cardinal vein, branch of posterior cardinal veins. The cells of lymphocyte-aggregate region assemble and reticulate. There are big lymphocyte, litter lymphocyte, plasma cell, monocyte, melano-macrophage and red celi. They are stained darkest in three region of head kidney. The granulocyte aggregate region is stained half tint. The endocrine tissue region is very undertone. There are 2 kinds of cell: inter-renal tissue cell and superrenal tissue cell (chromaffin cell). Inter-renal tissue cell is abundant in mitochondria and golgis apparatus vesicles, and a few secretive granules. Superrenal tissue cells distribute around posteriorcardinal veins and their branch, or in their walls. There is abundance of golgisapparatus vesicles in superrenal tissue cells. Some vesicles have electric dense secretive granules.31h15min after fecundating, pronephric anlage have formed when the embryo have 18 somites. From pro-nephros' genesis to head kidney development, it includes following stage: the pronephric anlage differentiation stage, the pronephric fold forming stage, the pronephric chamber forming stage, the pro-glomerulusforming stage, the mesenchymal cells move into pronephros and increment stage and the head kidney forming sta...
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