دراسة تشريحية و نسجية مقارنة للجهاز البولي مع تقدير بعض القيم الكيموحيوية للدم في ثلاث فقريات عراقية

Comparative Anatomical and Histological Study of the Urinary System with Estimation of Some Blood Biochemical Criteria in Three Iraqi Vertebrates

The present study aimed to investigate the morphological description and histological structure  of the excretory system in three species of Iraqi vertebrates (Pipistrella Kuhlii, Mauremys caspica caspica and Rana ridibunda ridibunda) in addition to investigate some physiological parameters represented by blood urea, blood creatinine and blood electrolytes (Sodium, potassium and calcium).

The physiological study revealed that there are some differences in concentration means of the studied blood parameters in turtle and frog. There were represented by (107.80±2.74mg/dl) and (29.73±1.40mg/dl) for mean concentration of blood urea frog and turtle respectively with significance differences (p<0.05).

The mean concentration of blood creatinine were (0.33±0.01mg/dl) in frog and (0.25±0.01mg/dl) in turtle with significance differences (p<0.05). The results also declear that the mean concentrations (sodium, potassium calcium) of blood electrolytes were (7.77±0.11mg/dl, 3.89±0.10mmol/l; 104.87±0.99mmol/l) in turtle and (8.85±0.10mg/dl, 5.14±0.12mmol/l; 96.40±0.84mmol/l) in frog with significance differences (P<0.05).

The comparative anatomical study revealed that kidney in Pipistrella kuhlii represented by a small solid structure bean like with dark red color. It is situated within the anterior half of the body cavity under the diaphragm, rested on the adipose connective tissue and surrounded by clear connective tissue capsule. The kidney of fresh water turtle represented by a solid elliptical structure with deep furrow on its surface made the kidney as lobulated structure. The kidney of turtle situated on both sides of  the vertebral column and it is as in bat rested on adipose connective tissue and surrounded by clear thick capsule.

On the other hand kidney in Iraqi frog represented by solid cylindrical elongated dark red color structure situated at both sides of vertebral column and surrounded by a capsule of thin connective tissue. The relationship between kidney weight and body weight were showed significantly difference (P<0.01) in all species under investigation.

Results of the present study showed that ureter of bat appeared as a clear tubular structure connected with the kidney at the hilum and it is wide at its anterior end and narrowed to word the posterior end where it is connected with the urinary bladder.

While the ureter of turtle was white tubular structure extend at the end of the anterior half of kidney’s ventral surface and connected with the urinary bladder. The Wolffian duct of the Iraqi frog represented by a tubular structure extend at the external side of the posterior half of kidney and opened at it’s posterior and in the cloaca.

The gross anatomy of the urinary bladder in bat showed that it is represented by small alveolar structure at the ventral surface within the pelvic region of the body cavity, while it was pear-shaped structured appeared as a muscular structure with long neck region opened in the cloaca. On the other hand the urinary bladder in frog appeared as a membranous sac like structure connected at its posterior end by the dorsal wall of the cloaca.

The results of histological study revealed that kidney tissue in bat differentiated into cortex and medulla, and the cortex occupied small area incomparison with medulla area. The cortex contains glomeruli distributed in high numbers at the regions near the medulla while they are less in their number at the peripheral region. On the other hand the medulla contains sections of thick and thin segments of Henle’s loop in addition to the sections of collecting tubules which forms the medullary rays. The kidneys of both turtle and frog showed no cortex and medulla and the glomeruli randomly distributed within the kidney tissue. They are concentrated more densely in peripheral region of turtle kidney while are concentrated in the middle region of frog kidney.

The histological examination showed that the nephron of kidneys in investigated animals consist of urinary corpuscle (Glomerulus and Bowman’s capsule) connected with the proximal convoluted tubule (PCT) which lead to Henle’s loop. Henle’s loop represented by thin and thick segment and lead at its posterior end to distal convoluted tubule (DCT). It is important to note that Henle’s loop not represented in turtle and frog nephrons.

Results of the present study revealed that kidney tubules of investigated animals have the same epithelial lining represented by simple cuboidal epithelium rested on basement membrane. The free surface of the lining epithelial cells in (PCT) have brush border while such border not appeared in (DCT). Histological examination also showed that collecting tubules of bat’s kidney lined by simple cuboidal epithelium, while the lining of the collecting tubules in turtle and frog were represented by simple columnar epithelium. The loop of Henle lined by simple squamous epithelium in its thin segment and by simple cuboidal epithelium in its thick segment.

The histological results showed that the ureter wall of bat and turtle consist of main layers represented by internal transitional epithelium supported by lamina propria and muscular layer surrounded by tunica adventitia of connective tissue. On the other hand the wall of Wolffian duct in frog consist of internal layer of pseudostratified columnar epithelium rested on basement membrane and muscular layer of smooth muscle fibers surrounded by connective tissue layer.

The histological examination showed that the urinary bladder wall are homologous in all investigated by internal layer of transitional epithelium supported by lamina propria and muscular layer surrounded by tunica adventitia.