Spermatogenic Cycle Length and Spermatogenic Efficiency in the Gerbil (Meriones unguiculatus)

Abstract

The gerbil (Meriones unguiculatus) is a rodent native of the arid regions of Mongolia and China. Because the gerbil can be easily bred in laboratory conditions, this species has been largely used as an experimental model in biomedical research. However, there is still little information concerning the testis structure and function in the gerbil. In this regard, we performed a detailed morpho-functional analysis of the gerbil testis and estimated the spermatogenic cycle length utilizing 3H-thymidine as a marker for germ cell progression during their evolution through the spermatogenic process. The stage frequencies of the XII stages characterized according to the acrosome formation and development were (I-XII) 13.8, 10.1, 8.1, 7.8, 4.0, 11.2, 7.5, 7.1, 5.9, 7.6, 8.1, and 8.9. The mean duration of each seminiferous epithelium cycle was determined to be 10.6 +/- 1.0 days and the total duration of spermatogenesis, based on 4.5 cycles, was approximately 47.5 days. The volume density of tubular and interstitial compartments was approximately 92% and 8%, respectively. Based on the volume occupied by seminiferous tubules in the testis and the tubular diameter, about 9 and 18 m of seminiferous tubules were found per testis and per gram of testis, respectively. Twelve primary spermatocytes were formed from each type A1 spermatogonia. The meiotic index was 2.8, indicating that 30% of cell loss occurs during meiosis. The number of Leydig and Sertoli cells per gram of the testis was 28 million and each Sertoli cell was able to support approximately 13 spermatids. The daily sperm production per gram of testis (spermatogenic efficiency) was 33 million. Taken together, these data indicate that, mainly due to the high seminiferous tubule volume density and Sertoli cell support capacity for germ cells, the gerbil presents high spermatogenic efficiency compared with other mammalian species already investigated. The data obtained in the present study might provide the basis for future research involving the reproductive biology in this species.

Spermatogenesis in goats with and without scrotum bipartition

“…In Stage 1 of the seminiferous epithelium cycle in goats, only one generation of primary spermatocyte results in the quantity of these cells in this species being different from that observed in other animals such as capybaras (Paula, 1999), agoutis (Assis Neto et al, 2003a), marmosets (Leal, 2004), collared peccaries (Costa et al, 2004), white-lipped peccaries (Costa et al, 2007), in which two generations of primary spermatocytes were detected. In some animals such as the gerbil (Segatelli et al, 2004) which have only one generation of primary spermatocytes in Stage 1, the number of these cells resembles that found for goats with different scrotal conformations.…”

Effect of season on structural composition of drake testes and daily spermatozoa production as determined by quantitative testicular histology

“…The tubular and luminal diameters of the tubules were measured randomly by choosing 30 round or nearly round tubular profiles per animal, irrespective of the cycle of the seminiferous epithelium. The height of the seminiferous epithelium was obtained using the same tubules that were used to determine the tubular diameter (22).…”

Neonatal Gonocyte Differentiation in Mongolian GerbilMeriones unguiculatusInvolves Asynchronous Maturation of Seminiferous Cords and Rapid Formation of Transitional Cell Stage

“…In the Mongolian gerbil, spermatogenesis begins at Week 2 of life and sexual maturity occurs at Week 10 (Ninomiya and Nakamura et al, 1987). The development of spermatogonia into spermatozoa in this species lasts $42.5 days and the seminiferous epithelial cycle comprises 12 stages (Segatelli et al, 2002(Segatelli et al, , 2004. Whereas some aspects of testicular histophysiology of gerbil are well known, others remain poorly studied including the neonatal differentiation of male germ cells.…”