Seasonal spermatogenic cycle and morphology of germ cells in the viviparous lizard Mabuya brachypoda (Squamata, Scincidae)

Abstract

We describe seasonal variations of the histology of the seminiferous tubules and efferent ducts of the tropical, viviparous skink, Mabuya brachypoda, throughout the year. The specimens were collected monthly, in Nacajuca, Tabasco state, Mexico. The results revealed strong annual variations in testicular volume, stages of the germ cells, and diameter and height of the epithelia of seminiferous tubules and efferent ducts. Recrudescence was detected from November to December, when initial mitotic activity of spermatogonia in the seminiferous tubules were observed, coinciding with the decrease of temperature, photoperiod and rainy season. From January to February, early spermatogenesis continued and early primary and secondary spermatocytes were developing within the seminiferous epithelium. From March through April, numerous spermatids in metamorphosis were observed. Spermiogenesis was completed from May through July, which coincided with an increase in temperature, photoperiod, and rainfall. Regression occurred from August through September when testicular volume and spermatogenic activity decreased. During this time, the seminiferous epithelium decreased in thickness, and germ cell recruitment ceased, only Sertoli cells and spermatogonia were present in the epithelium. Throughout testicular regression spermatocytes and spermatids disappeared and the presence of cellular debris, and scattered spermatozoa were observed in the lumen. The regressed testes presented the total suspension of spermatogenesis. During October, the seminiferous tubules contained only spermatogonia and Sertoli cells, and the size of the lumen was reduced, giving the appearance that it was occluded. In concert with testis development, the efferent ducts were packed with spermatozoa from May through August. The epididymis was devoid of spermatozoa by September. M. brachypoda exhibited a prenuptial pattern, in which spermatogenesis preceded the mating season. The seasonal cycle variations of spermatogenesis in M. brachypoda are the result of a single extended spermiation event, which is characteristic of reptilian species.

Histological study and immunohistochemical location of cytoskeletal proteins in the testis and epididymis of the three species of lizards of the family Leiosauridae (Reptilia: Squamata)

“…Histologically, in the testis of the lizards E. bilineatus, E. perditus and U. vautieri , the presence of cells of the spermatogenic lineage, of Sertoli cells, and peritubular myoid cells are similar characteristics to those described in T. itambere (Ferreira et al, 2009); T. torquatus (Silva et al, 2016); L. ocellata (Pewhom & Srakaew, 2018); and other lizards like Mabuya brachypoda (Hernández‐Franyutti & Uribe, 2012) and Sceloporus grammicus (Lozano et al, 2015).…”

Microanatomy of the testes and testicular ducts of the butterfly lizard, Leiolepis ocellata Peters, 1971 (Reptilia: Squamata: Agamidae) during the active reproductive period

“…An exception is the turtle Kinosternon scorpioides , in which 10 stages of the seminiferous epithelium have been described (Sousa, Campos‐Junior, Costa, & de França, ). Among meiotic germ cells, pachytene spermatocytes are the most abundant during spermatogenesis of the L. ocellata testes, as in other reptiles (Gribbins et al, , , ; Hernández‐Franyutti & Uribe, ; Villagrán‐SantaCruz et al, ), suggesting that this meiotic phase is prolonged to allow for genetic recombination between paired homologous chromosomes (Gribbins, ). Unlike mammalian acrosomal vesicles that are detectable using PAS histochemistry, this technique could not be applied to stain the acrosomal vesicles of L. ocellata for the identification of the spermatid steps due to poor staining properties of these subcellular structures, as also described previously (Lancaster et al, ).…”

“…Unlike mammalian acrosomal vesicles that are detectable using PAS histochemistry, this technique could not be applied to stain the acrosomal vesicles of L. ocellata for the identification of the spermatid steps due to poor staining properties of these subcellular structures, as also described previously (Lancaster et al, ). Gribbins () has suggested that the number of reptilian spermatid steps is relatively consistent, with seven steps (Gribbins & Gist, ; Gribbins et al, , , ; Gribbins, Happ, & Sever, ; Hernández‐Franyutti & Uribe, ; Konvalina et al, ; Lancaster et al, ; Rheubert, Mchugh, Collier, Sever, & Gribbins, ; Rheubert, Poldemann, et al, ; Siegel et al, ; Villagrán‐SantaCruz et al, ), eight steps (Gribbins et al, , ; Wang, Wu, Xu, Wang, & Wang, ) or uniquely 10 steps (Sousa et al, ). Likewise, spermatids of L. ocellata are classified into eight ontogenetic steps.…”

Ductuli efferentes of the male Golden Syrian hamster reproductive tract

“…He described the tubules as being very thin and “coiled individually from side to side”. Since then, efferent ductules have been described in more than 20 different mammalian (Hess, 2002; Ilio & Hess, 1994) and numerous nonmammalian vertebrate species (Guerrero et al ., 2004; Hernandez-Franyutti & Uribe, 2012; Hess et al ., 1976; Holmes & Gist, 2004; Rheubert et al ., 2010; Sever & Freeborn, 2012). Efferent ductules transport spermatozoa from rete testis to the epididymis.…”