Melanocytes in the Testes of Eupemphix nattereri (Anura, Leiuperidae): Histological, Stereological, and Ultrastructural Aspects

Abstract

Ectothermic vertebrates have a well-developed system of melanincontaining cells, which localize in several organs and tissues and compose an extracutaneous pigmentary system. This research aimed at characterizing histological and ultrastructural patterns of pigmented cells in the testes of the anura Eupemphix nattereri (Steindachner, 1963), including the stereological and quantitative evaluation of this cell type in the gonads. Ten adult males were collected in Nova Itapirema, Sã o Paulo, Brazil, and submitted to morphological studies with light and transmission electron microscopy. The testis presents a great number of large cells with many brown granules and long cytoplasmic processes. The pigmented cells found in the testis are structurally similar to melanocytes, characterized by large amounts of melanosomes. The cells may be in intimate contact with the same cell type, with myoid cells surrounded by a large amount of collagen fibers, Leydig cells, and next to fibroblasts. The distribution and amount of extracutaneous melanocytes is variable when other organs and membranes are analyzed, allowing the establishment of species-specific patterns for the extracutaneous pigmentary system. Anat Rec, 290:795-800, 2007Rec, 290:795-800, . 2007 Wiley-Liss, Inc.

The evolutionary ecology of testicular function: size isn't everything

“…This in turn may require special adaptations to protect sperm from oxidative stress (Almbro, Dowling & Simmons, 2011), and it has been suggested that testicular melanisation (i.e. the incorporation of pigments into the tissues of the testis) might have this function (Zieri, Taboga & De Oliveira, 2007;Galvan, Møller & Erritzøe, 2011) (although this has also been suggested to be linked to thermoregulation of spermatogenesis in a lizard that shows a striking pattern of unilateral testicular melanisation; Guillette, Weigel & Flater, 1983). A case in point is the three-spined stickleback (Gasterosteus aculeatus), where sperm are made several months before the mating season and stored in the testis (Borg, 1982;Zbinden, 2001), where the testis is strongly melanised (Mehlis et al, 2012), and where brood care and territorial defence are very energy demanding (Smith & Wootton, 2005).…”

Male reproductive traits of full-sibs of different age classes in three-spined sticklebacks (Gasterosteus aculeatus)

“…Testis melanisation occurs in many animal taxa, for example in fish (Louiz et al 2009), amphibians (Zieri et al 2007), reptiles (Guillette et al 1983), birds (Galván et al 2011), and mammals (Poole and Lawton 2009). In birds, for example, testicular melanisation has been evolved in species with high rates of accumulated mitochondrial mutations and has been supposed to be an adaptive response related to the protective capacity of melanin against oxidative stress (Galván et al 2011).…”

Inbreeding in three-spined sticklebacks (Gasterosteus aculeatusL.): effects on testis and sperm traits

“…In several vertebrates, testes are covered by melanophores that contain melanin, such as in fish (Louiz, Ben-Attia & Ben-Hassine, 2009), amphibians (Zieri, Taboga & De Oliveira, 2007), reptiles (Guillette, Weigel & Flater, 1983), birds (Galván et al, 2011), and mammals (Poole & Lawton, 2009). Melanophores contain dark pigments, which are assumed to protect the testes from deleterious UV light as a result of their strong light absorbance (Kaidbey et al, 1979;Plonka et al, 2009) or to protect male germ cells from oxidative stress (Galván et al, 2011).…”