Spermatogenesis in the turkey (Meleagris gallopavo): Quantitative approach in immature and adult males subjected to various photoperiods

Abstract

The objectives of this study were to identify and quantitate the germ cell populations of the testes in sexually mature male turkeys (Trial 1), determine the duration of meiosis based on BrdU labeling and stereological analyses (Trial 2), and examine the impact of various photoperiods on germinal and somatic cell populations in immature and adult males (Trial 3). In Trial 1, both testes within a male had similar stereological components (P > 0.05) for all parameters analyzed. In Trial 2, the duration of Type-1 spermatocytes and round spermatids in turkeys lasted 4.5 AE 0.5 and 2.0 AE 0.5 days, respectively. In Trial 3, the short photoperiod (7L:17D) delayed testicular growth (in the stereological parameters analyzed). In contrast, the effect of a moderately short photoperiod (10.5L:13.5D) was comparable to the effect of a long (14L:10D) or increasing photoperiod (7L:17D to 14L:10D) on the stereological parameters examined. With the exception of the short photoperiod, all other photoperiods used in this study induced comparable early testicular maturation, with maximum testis www.journals.elsevierhealth.com/periodicals/the Theriogenology 65 (2006) 845-859Abbreviations: El, elongated spermatids; Fwt, testes fragment weight; MR, meiotic ratio; Ø, seminiferous tubule diameter; u, mean lifespan; nSert, Sertoli cell counts; nSpcI, primary spermatocyte counts; nSpdR, round spermatid counts; NSert, total number of Sertoli cells per testes; NSpcI, total number of Type-I spermatocytes per testes; NSpdR, total number of round spermatids per testes; Sert, Sertoli cells; SE, seminiferous epithelium; Spg, spermatogonia; Spc I, Type-I spermatocytes; SpcII, Type-II spermatocytes; SpdR, round spermatids; ST, seminiferous tubule; Tspz, testicular spermatozoa; TSP, testicular sperm production; V r , relative volume * Corresponding author. Tel.: +33 2 47 42 7645; fax: +33 2 47 42 7778.E-mail address: brillard@tours.inra.fr (J.-P. Brillard). This article is a U.S. government work, and is not subject to copyright in the United States.weight at 29-35 weeks of age. As the males got older, there was a progressive, linear decline in testis weight through 60 weeks, at which time there were no significant differences among photoperiods. In conclusion, the duration of meiosis in the turkey was similar to that observed in the fowl and guineafowl. The existence of a threshold of photosensitivity to gonad stimulation in male turkeys is suggested to be between 7.0 and 10.5 h of light. #

Effect of various photoperiods on testicular weight, weekly sperm output and plasma levels of LH and testosterone over the reproductive season in male turkeys

“…This confirmed previous reports that a strictly short photoperiod per se (7L or 8L/day) has a non-stimulatory effect on reproductive traits (fowl: [29,30]; turkey: [10,11]; guinea-fowl: [20]). By contrast, in male turkeys a moderate or even shorter photoperiod such as 10.5L:13.5D from 23 wk of age appeared to be stimulatory by 30-34 wk of age.…”

“…Previous studies using commercial breeder turkeys revealed a high degree of sensitivity to photoperiod for TW [10,11], semen output [18], and circulating LH and testosterone concentrations [6][7][8][9]. The present results confirmed previous observations [10,11] that prepubertal male turkeys maintained under constant long days are precocious semen producers (26-29 wk) In . Each point represents the mean AE S.E.M.…”

“…A nonreversible regression of the testes followed the onset of sexual maturity in turkey males exposed to long photoperiods from the first weeks after hatching [10]. Alternatively, short photoperiods (7L:17D) delayed the onset of testicular development and semen production, but maintained it longer into the season [10,11].…”

Specific features of in vivo and in vitro sperm storage in birds

“…Another specific feature of reproduction in males of avian species is the relatively short interval of time required for B-type spermatogonia to evolve into spermatozoa compared with mammals. For example, in the chicken, guinea-fowl, duck and turkey, the duration of spermatogenesis is approximately 14 days (De Reviers, 1968;Marchand et al, 1977;Brillard, 1981;Noirault et al, 2006), which provides males with extended potential to produce large quantities of gametes within a given period of time. Following their evacuation from the rete testis, avian sperm are rapidly transported through the epididymis to the vas deferens, where they are stored for a limited period of time (e.g.…”

Chicken Testicular Stem Cells

“…A morphological description of the various cell categories involved in the processes of avian spermatogenesis has already been proposed in several species (Zhao et al, 2002;Siu et al, 2004;Brillard 1986;Lin and Jones, 1990;Thurston et al, 2000;Goes and Dolder, 2002;Noirault et al, 2006) but the identification of stem spermatogonia on the basis of cell surface markers has been achieved only recently (Bakst et al, 2007). The precise identification of germinal stem cell populations, particularly that of spermatogonial stem cells, might be very helpful for efficient and reproducible transplantation and repopulation of recipient seminiferous epithelium.…”