<div>Background: Kidneys, the paired organ which essentially plays for excreting nitrogenous wastes, excessive water, inorganic salts and toxic substances produced during the process of body metabolism. Maintenance of osmotic regulation and homeostatic fluid balance of the body has also be performed by kidneys. Each of the kidneys filtrate carried to cloaca by respective ureter from where the urine leaves the body. The present macroscopic, histomorphological and histochemical studies undertaken on the Kidneys of Guinea fowl (Numida meleagris) is nothing but the attempt to widen our thrust area for that bird which is nonexistent as on documentation. 
 
Methods: The present studies were carried upon 12 pairs of in-vitro kidney samples in Guinea fowl. Gross morphology and morphometrical observations were carried on fresh specimens. Histological studies were carried on fixed samples those were processed for dehydration, clearing, embedding into paraffin and sections of 5-6 &mu; thickness were obtained. Different staining procedure as to Haematoxylin and Eosin, Silver orcein, Aniline blue and Weigert&rsquo;s staining methods were employed for different histological components. The histochemical and histoenzymic studies were also accomplished with Periodic acid Schiff&lsquo;s (PAS), Alcian blue methods (pH-2.5) and Gomori&rsquo;s cobalt method for Alkaline phosphatase and Acid phosphatase. The Succinic dehydrogenase enzyme was also estimated on cryostat sections. 
 
Result: The observations on kidneys of Guinea fowl were accomplished after macroscopic, histomorphological and histochemical means. This reddish-brown colored paired organ of kidneys was retroperitoneally placed in synsacral fossa and had incomplete division of three parts. The wrapping material of capsule was the dense connective tissue. The outer cortex and inner medulla had different parts of nephrons. Two types of nephrons viz. mammalian type (with Henle loop) and reptilian type (without Henle loop) were observed. Collagen, elastic and reticular fibers were there in different components of the kidney. Histochemically it has determined the secretion of neutral as well as acidic mucopolysaccharide substances. PAS activity was observed at mesangial cells and basement membrane of DCT. The Alkaline phosphatase showed the positive activity in capsule, brush border of proximal and distal convoluted tubules. The Acid phosphatases were showing intense activity in parietal and visceral layer of renal corpuscles, lumen and basement membrane of PCT. The intense activity of Succinic dehydrogenase showed at PCT, DCT, collecting tubule whereas renal corpuscles showed feeble activity.</div>

<div>Macroscopic, Histomorphological and Histochemical Studies on the Kidneys of Guinea Fowl (Numida meleagris)</div>

Background:&nbsp;The kidneys manage body fluids and electrolytes in addition to performing osmoregulation and metabolic waste disposal. The goal of the present study was to investigate the structural characteristics of the kidneys of two tetrapod species; Ptychadena mascarenensis (Mascarene frog) and Chalcides ocellatus ocellatus (Ocellated skink) concerning their habitat, which could be linked to unique structural renal differences. 
 
Methods:&nbsp;During December 2020, four specimens of each species were obtained from various locations in Egypt. The animals were captured alive and were suffocated by inhaling chloroform. There kidneys were removed and processed for morphological, histological and electron microscopy examinations. 
 
Result: Ptychadena mascarenensis and Chalcides ocellatus ocellatus have groups of nephrons in their kidneys and each nephron consists of a renal corpuscle, an intermediate segment, a proximal tubule, a distal tubule and a collecting duct system. The renal corpuscles and tubules were dispersed throughout the cortex and medulla of both species so the cortex and medulla were not differentiated. In the two tetrapod classes Amphibia (Ptychadena mascareniensis) and Reptilia (Chalcides ocellatus ocellatus), some differences in the morphological, histological and ultrastructural features of the kidney have been identified. Animals use each of these structures to help them adapt to their surroundings.

Comparative Study on the Kidneys of Ptychadena mascarenensis and Chalcides ocellatus ocellatus in Relation to Their Environment