الفهرس 
IntroductionOnly 14 pages are availabe for public view
 |  | from | 471 |  |  |
| | | from | 471 | | |
Abstract
This study was carried out on 48 quail embryos collected from incubated eggs of Japanese quail (Coturnix coturnix japonica) from day (3,5,7,9,11,13,15and 17). In addition to 16 quail chicks were collected at the ages of (1 day, 2wks, 4wks and 8wks) post hatching for the histological, immunohistochemical, SEM, semithin and TEM investigations to explain the histology of quail kidney in pre &post- hatching periods.
The present study revealed that the pronephros was observed on E3 represented by, pronephric duct pronephric tubules, nephrostome, and external glomerulus. The mesonephros also appeared at this age, and it was formed of mesonephric duct, mesonephric tubules and primordia of the internal glomerulus. The functional mesonephric renal corpuscle appeared firstly on ED5, at this time also, the mesonephric tubules distinguished into proximal secretory and distal collecting tubules. The primordium of metanephros appeared on ED5 and appeared as a metanephric diverticulum (Ureteric bud) surrounded by nephrogenic tissue. On ED9 the first signs of mesonephric regression appeared on the cranial part.
On E11, the first appearance of functional nephron was evident with mature renal corpuscles and renal tubules distinguished into proximal and distal ones. On E13, a complete renal filtration barrier was observed, the nephrons were more developed as they formed the thick segment of Henle loop, and the proximal convoluted tubule was well differentiated and had numerous microvilli, and tubular invaginations.
The present work showed that podocytes in quail exhibited an elaborate morphology with several primary processes radiating from the cell body to embrace the glomerular capillaries. As, VEGF plays a vital role in the induction of nephrogenesis and vasculogenesis, it was expressed within the glomerular capillaries, the podocytes of developing and adult kidneys, and some interstitial cells.
During the development, the cells of proximal convoluted tubules contain abundant ribosomes, rER, and mitochondria, in addition to numerous lipid droplets distributed within their cytoplasm. Tight junctions were well-distinct between adjacent cells.
On one-day post-hatching, the mammalian-type nephron completed its formation by the appearance of the thin segment of Henle loop. The present work revealed that a complete juxtaglomerular apparatus was observed in quail kidney at one day post-hatching. It was represented by granular juxtaglomerular (JG) cells, extraglomerular mesangial cells (Lacis) and macula densa. This apparatus was formed during metanephric development, where primitive extraglomerular mesangial cells and primitive macula densa were seen at the E15, but the granular JG cells couldn’t be detected.
The most interesting finding in our study was the observation of the granulated peripolar cells (PPCs) at the vascular pole of renal corpuscle in adult quail kidney. The main identifying characteristic of these cells is the presence of cytoplasmic granules. Several functions were reported to these cells include; the control of water and electrolyte excretion, regulation of renal blood flow and systemic blood pressure, as well as cting in concert with the renin-angiotensin-aldosterone system and stimulate the release of active renin.
NSE immunoreactivity was demonstrated in PPCs, the epithelial cells of Bowman’s capsule, macula densa, distal tubule, cortical collecting duct and medullary duct.
Our results recorded that the nephrogenesis was continuous for 2weeks after hatching, it was confined by the presence of condensate mesenchymal tissue zones (undifferentiated nephrogenic tissue). This is supported by a strong immunopositivity of these mesenchymal tissue zones to β catenin. In addition, our study found that β catenin was also expressed in the developing and adult kidneys, at the level of cell membrane in the glomerular endothelium and tubular epithelial cells. Moreover, β catenin was expressed in the mesonephric duct (Wolffian duct) at ED5 & 7. β-catenin is multifunctional protein that involved in kidney development.
Our study revealed that the collecting tubule had dark (intercalated cells) and mucous secreting cells. The intercalated cells apparently secrete hydrogen ions into the urine in exchange of potassium.
In this study, the renal interstitial tissue contains the fibroblasts mainly, macrophages and telocytes. Theses cells may play roles in tissue regeneration and reparation. and may be involved in the maintenance of tissue homeostasis.