Seasonal spermatogenesis in the Mexican endemic oviparous lizard,Sceloporus aeneus(Squamata: Phrynosomatidae)

Abstract

Oviparous species of exhibit either seasonal or continuous spermatogenesis and populations from high-elevation show a seasonal pattern known as spring reproductive activity. We studied the spermatogenic cycle of a high-elevation (2700 m) population of endemic oviparous lizard,, that resided south of México, D.F. Histological analyses were performed on the testes and reproductive ducts from individual lizards collected monthly. This population of showed a seasonal pattern of spermatogenesis, with 4 successive phases common in other lizards. These include: 1) Quiescence in August, which contained solely spermatogonia and Sertoli cells; 2) Testicular recrudescence (September-January) when testes became active with mitotic spermatogonia, spermatocytes beginning meiosis, and the early stages of spermiogenesis with spermatids; 3) Maximum testicular activity occurred from March to May and is when the largest spermiation events ensued within the germinal epithelia, which were also dominated by spermatids and spermiogenic cells; 4) Testicular regression in June was marked with the number of all germs cells decreasing rapidly and spermatogonia dominated the seminiferous epithelium. February was a transitional month between recrudescence and maximum activity. The highest sperm abundance in the lumina of epididymides was during maximum testicular activity (March-May). Thus, before and after these months fewer spermatozoa were detected within the excurrent ducts as the testis transitions from recrudescence to maximum activity in February and from maximum activity to quiescence in June. Maximum spermatogenic activity corresponds with warmest temperatures at this study site. This pattern known as spring reproductive activity with a fall recrudescence was similar to other oviparous species of genus

Reproductive cycle of the oviparous lizard Sceloporus jalapae, from Zapotitlán Salinas, Puebla, Mexico

“…The study of reproductive patterns of oviparous and viviparous species of temperate and tropical environments (Bustos‐Zagal, Méndez‐de la Cruz, Castro‐Franco, & Villagrán‐Santa Cruz, ; Dunham et al., ; Gadsden, Rodríguez‐Romero, Méndez‐de la Cruz, & Gil‐Martínez, ; García‐Collazo et al., ; Guillette & Casas‐Andreu, ; Hernández‐Gallegos, Méndez‐de la Cruz, Villagrán‐Santa Cruz, & Andrews, ; Hernández‐Gallegos et al., ; Manríquez‐Morán, Villagrán‐Santa Cruz, & Méndez‐de la Cruz, ; Méndez‐de la Cruz, Guillette, Villagrán‐Santa Cruz, & Casas‐Andreu, ; Méndez‐de la Cruz & Villagrán‐Santa Cruz, ) has shown differences in reproductive phenology between the species of Sceloporus . In temperate areas, reproductive activity of oviparous species is limited to spring and summer months in species such as S. aeneus , S. occidentalis , S. scalaris and S. spinosus (Goldberg, ; Guillette, , ; Hernández‐Gallegos et al., ; Manríquez‐Morán et al., ; Méndez‐de la Cruz, Villagrán‐Santa Cruz, López Ortíz, & Hernández‐Gallegos, ; Newlin, ); vitellogenesis and ovulation occur in spring, oviposition in late spring and the birth of hatchlings in late summer and fall. Reproductive activity in these species is associated with high temperature and humidity (Méndez‐de la Cruz et al., ).…”

Lack of spermatogenic variation in a polymorphic lizard, Sceloporus aeneus (Squamata: Phrynosomatidae)

“…During May 2015 (i.e., peak reproductive period, Hernández‐Gallegos et al., ), 15 adult males (five grey, five yellow and five orange) of S . aeneus were collected (Scientific Collector Permit SEMARNAT FAUT 0186) at Calimaya, Estado de México, Mexico (19º10′50′′ N, 99º36′18.8′′ W; 2646 masl).…”

“…During May 2015 (i.e., peak reproductive period, Hernández-Gallegos et al, 2014), 15 adult males (five grey, five yellow and five orange) of S. aeneus were collected (Scientific Collector Permit SEMARNAT FAUT 0186) at Calimaya, Estado de México,Mexico (19º10′50′′ N,99º36′18.8′′ W; 2646 masl). Individuals were sacrificed using an intracoelomic injection of sodium pentobarbital (10%) following ethical guidelines of the Universidad Autónoma del Estado de México.…”

“…In accordance with previous studies on spermatogenic cycles, conventional histological techniques were performed on testicular tissues included the following: dehydration via graded ethanol, clearing tissues in xylene and embedding tissues in paraffin (Granados-González et al, 2015;Hernández-Gallegos et al, 2014;Rheubert et al, 2014). Embedded samples were then cut at 5 μm using a rotatory microtome, placed on albuminized slides and stained with haematoxylin-eosin for general cytology.…”

“…Sceloporus aeneus is a Mexican endemic oviparous lizard with maximum testicular activity of spermiogenesis and spermiation occurring from March to May (Hernández-Gallegos et al, 2014). As colour polymorphism has been recorded in congeneric Sceloporus (Bustos Zagal et al, 2014), adult males of S. aeneus exhibit a lateral colour polymorphism including three morphs: grey, yellow and orange (Jiménez-Arcos, 2013).…”