Male reproductive cycle in Aspidoscelis costata costata (Squamata: Teiidae) from Tonatico, Estado de México, México

Abstract

The purpose of this study was to investigate the reproductive cycle of a high‐elevation population of Aspidoscelis costata costata (1500–1600 m) and compare its reproductive cycle with that of other populations, species, and closely related genera. Adult male A. costata costata lizards were collected, and the reproductive tracts were removed and subjected to histological analyses. Testicular activity commences in March with maximum testicular activity and highest sperm abundance (in the epididymides) occurring between May and July. The testis remains at peak activity until September when a late regression/early quiescent phase is observed. Leydig cells follow this same pattern except these hormone‐producing cells remain at maximum secretory level through September. Sperm are present in the epididymides in April–September. This pattern is consistent with the spring recrudescence found in a multitude of male lizard taxa. However, this differs from the continuous cycle observed in some tropical Teiid species and other lizard taxa at high elevation. This study indicates that our knowledge about lizard spermatogenic cycles remains incomplete, and additional studies are required to fully understand the interactions between phenotype, evolution, phylogenetics and environment.

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

“…However, although no statistical analyses were performed, February showed intermediate quantity of spermatozoa in the epididymis with respect to the massive spermatozoa release recorded during maximum testicular activity (March-May). The present data, along with numerous other studies, [1][2][3][4] suggest that histological data is the most accurate technique compared to size of testis (volume or mass) alone in determining the seasonality of male reproductive/germ cell activity and length of different phases of the spermatogenesis. Therefore, studies involving exclusively macroscopic data to evaluate the male reproductive cycle should be interpreted with caution.…”

“…[1][2][3]11,20 We agree with the efforts in using multiple indicators to describe the spermatogenic cycle of lizards, especially designs that include histological examination of reproductive organs. [1][2][3][4][5][6][7][8][9][10][11][20][21] However, the use of a single indicator may be misleading. For example, some of the data collected for S. aeneus (testis mass) suggest that February should be included in the months classified as maximum testicular activity (Table 1).…”

“…These findings are consistent with previous studies in which warmest temperatures appear to favor the maximum spermatogenic activity. 1,30 Experimental studies through manipulation of reproductive cues for gonadal development 31 represent one important step in the understanding of male reproductive cycle control in lizards and other reptiles.…”

“…These characterizations are made by the use of histological examinations, which strongly support the various spermatogenic stages in contrast to other types of evidence, such as testicular size (i.e., volume or mass) and/or opaqueness of the extratesticular ducts. [1][2][3][4] Although both seasonal and continuous spermatogenesis have been observed in lizards, seasonal spermatogenesis is by far the most common type of male germ cell cycle. This pattern has been recorded in different genera within Phrynosomatid lizards including: Phrynosoma, 5 Uma, 6 Cophosaurus, 7 Uta, 8 Petrosaurus, 9 Urosaurus, 10 and Sceloporus.…”

Reproductive biology of Philodryas patagoniensis (Snakes: Dipsadidae) in south Brazil: male reproductive cycle

“…patagoniensis exhibits spatial germ cell development of the testes, which is a common strategy seen within most of the amniotes (Granados-Gonz alez et al 2015). patagoniensis exhibits spatial germ cell development of the testes, which is a common strategy seen within most of the amniotes (Granados-Gonz alez et al 2015).…”