Morphological and histological characterization of sexual segment of the kidney in Notomabuya frenata (Cope, 1862) and Aspronema dorsivittatum (Cope, 1862) (Squamata, Mabuyidae)

Abstract

The kidneys in two viviparous species of Neotropical lizards, Notomabuya frenata and Aspronema dorsivittatum (Mabuyidae), were investigated by light and scanning electron microscopy in order to determine the presence of the sexual segment of the kidney (SSK) and to study its morphology. The individuals used in this study belong to the Herpetological Collection of the Herpetology Laboratory - Reptiles of the Federal University of Juiz de Fora (CHUFJF-Reptiles) and they were collected between the years 2008 and 2012 from the Cerrado region in the state of Minas Gerais, Brazil. The SSK was present only in sexually mature males (with sperm in the testes / epididymis), whereas it was absent in sexually immature males. The nephron in both species consists of renal corpuscle, proximal convoluted tubule, distal convoluted tubule, collecting duct and sexual segment of the kidney. The SSK of the analyzed species were coated with a simple columnar epithelium, with high cells, basal nucleus and in the apical portion innumerable secretory granules. This study adds to the knowledge on reproductive biology and structures related to reproductive strategies of both lizard species and viviparous Neotropical lizards.

Histochemical and ultrastructural investigations on the renal parenchyma of the Egyptian Nile Monitor Lizard (Varanus niloticus)

“…Their nuclei were surrounded by a thin border of cytoplasm which projected into the glomerular lumen. This was in accord with what was described for the glomerular endothelial cells of other vertebrates and in the capillary endothelial cells of glands associated with internal secretion (Anderson, 1960;Novelli et al, 2018). Additionally, detection of dendritic cell which is an antigen-presenting cell within the endothelial lumen indicates a potential role in the renal immune system.…”

“…In the present study, the renal corpuscles were small, few in number, but complex in their microscopic structure as they were consisted of double-layered Bowman's capsule surrounding the glomerular capillaries. Similar description was identified for the renal corpuscle of other lizards and snakes (Khalef & Ata, 2010;Novelli et al, 2018). Such smaller size and complex microscopic structure of the renal corpuscle denote that they are specialized to minimize the glomerular filtration rate and consequently retaining a primary control on the probable water loss.…”

“…Absence of the loop of henle which constitutes the main structural basis for the formation of a hyperosmotic urine suggests that reptiles, especially those inhabit the terrestrial environments like Nile monitor lizards, must have structural specialization to help them to utilize their environments effectively and to prevent excessive water loss from their bodies. Such specializations should apparently involve both the renal corpuscle and the renal tubules (Peek & MCMillan, 1979;Novelli et al, 2018).…”

“…A differentiated portion of the renal tubules with a granular cytoplasmic matrix known as the sexual segment could be considered as a characteristic trait of the reptiles' kidney (Novelli, Oliveira, Castanon, Silva, & Sousa, 2018). It was detected in the adult male renal tissue.…”

“…The function of the sexual segments is still unknown. However, it is proposed to be similar to the mammalian seminal vesicle as they both similarly respond to androgens (Novelli et al, 2018).…”