HISTOLOGICAL AND STEREOLOGICAL STUDY ON THE KIDNEYS IN SPARROWS LIVING IN WET AND ARID ZONES

Abstract

The structure of the kidneys of sparrows living in wet and arid zones was compared to each other. A stereological study was conducted to quantify the components of the bird’s kidneys. A total of 10 female sparrows living in wet and arid zones were collected. The length of the kidneys was measured before blocking. The transverse serial sections were taken with a thickness of 5 μm. The sections were stained with haematoxylin and eosin (H & E) as well as periodic acid Schiff- alcian blue (PAS- AL). The kidneys of the sparrows consisted mostly of a cortex with only a small portion as medulla. The medulla was arranged in the form of cones with different lengths, which were randomly distributed within the kidney. The medullary nephron tubules were arranged sequentially. Thick and thin limbs of loop of Henle were separated by the collecting ducts. The histological structure and absolute volumes of the kidneys and components of the nephron were quantified. The absolute volumes of the structures within the right and left kidneys were not significantly different. The volume of the whole kidney (p<0.001) in the wet zone was larger than that in the arid zone. Furthermore, the volume proportion of the proximal tubule as well as cortex to whole kidney size was higher than that in wet zone birds. Whereas, the volume proportion of the medulla, distal tubule, cortical collecting tubule, medullary collecting duct and thin limb of loop of Henle to whole kidney size was higher than that in arid zone birds (p≤0.001). This feature indicates that the arid zone bird species had a more high ability to conserve water by producing concentrated urine. Key words: sparrow; stereology; histology; kidney; environment ><0.001) in the wet zone was larger than that in the arid zone. Furthermore, the volume proportion of the proximal tubule as well as cortex to whole kidney size was higher than that in wet zone birds. Whereas, the volume proportion of the medulla, distal tubule, cortical collecting tubule, medullary collecting duct and thin limb of loop of Henle to whole kidney size was higher than that in arid zone birds (p≤0.001). This feature indicates that the arid zone bird species had a more high ability to conserve water by producing concentrated urine.Key words: sparrow; stereology; histology; kidney; environmentHISTOLOŠKA IN STEREOLOŠKA ŠTUDIJA LEDVIC VRABCEV, ŽIVEČIH V VLAŽNIH IN SUHIH OBMOČJIHPovzetek: V opisani raziskavi smo primerjali strukturo ledvic vrabcev, ki živijo v vlažnih in sušnih območjih. Izvedena je bila stereološka raziskava, s katero smo količinsko opredelili različne tkivne strukture v ptičjih ledvicah. Zbrali smo vzorce 10 samic vrabcev, ki živijo v vlažnih in sušnih območjih. Pred nadaljnjo histološko obdelavo vzorcev smo izmerili dolžino ledvic. Pripravljene so bile prečne serijske rezine ledvic debeline 5 μm. Rezine so bile obarvane s hematoksilinom in eozinom (barvanje H&E) ter s PAS histokemijsko reakcijo z dodatkom alcianskega modrila (PAS-AL). Ledvice vrabcev so večinoma sestavljala področja skorje in manjši deli sredice. Sredico so sestavljali stožci različnih dolžin, ki so bili naključno razporejeni znotraj ledvice. Središčne cevke nefrona so potekale ena ob drugi. Debelejši in tanjši deli zanke nefrona so bili ločeni z zbirnimi cevkami. Histološka zgradba ledvic, absolutna prostornina ledvic in sestavni deli nefrona so bili kvantitativno ovrednoteni. Absolutna prostornina struktur se med levo in desno ledvico ni značilno razlikovala. Prostornina celotne ledvice vrabcev v vlažnem območju je bila večja od prostornine ledvic vrabcev iz sušnega področja (p < 0,001). Poleg tega je bil prostorninski delež proksimalne cevke in področje skorje v primerjavi s celotno velikostjo ledvic večji pri pticah iz sušnega področja kot pri pticah iz vlažnega področja. Prostorninski delež sredice, distalne cevke, zbirne cevke v skorji, zbirnega kanala v sredici in tankega dela zanke nefrona v celotni velikosti ledvic pa je bil višji pri vrabcih iz vlažnih področij kot pri vrabcih iz sušnih področij (p ≤ 0,001). Opisane značilnosti ledvic kažejo na to, da bi lahko imele ptice iz sušnih območij večjo sposobnost ohranjanja vode s proizvodnjo koncentriranega urina.Ključne besede: vrabec; stereologija; histologija; ledvica; okolje