Suppression of male reproductive activity by estradiol in goldfish: appearance of infertile males that perform active spawning behavior

The anatomy and histology of the male reproductive tract of the dugong (Dugong dugon) is described. Each testis and its adjacent epididymis lie immediately caudal to the corresponding kidney. The seminal vesicles are large but there is no discrete prostate gland and the bulbo-urethral glands are also diffuse. Both qualitative and quantitative examination of the testes and epididymides of 59 males whose ages have been estimated from tusk dentinal growth layer counts indicate that the male dugong does not produce spermatozoa continuously, despite the absence of a distinct breeding season. Individual dugongs were observed with testes at all stages between complete quiescence and full spermatogenesis, and only 10 of the 40 mature males had fully spermatogenic testes and epididymides packed with spermatozoa. Androgenic and spermatogenic activity of the testes appeared to be in phase, but the testicular histology of some old males suggested that they may have been sterile for long periods.

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Testicular Melatonin and Its Pathway in Roe Deer Bucks (Capreolus capreolus) during Pre- and Post-Rut Periods: Correlation with Testicular Involution

Animals ◽

10.3390/ani11071874 ◽

2021 ◽

Vol 11 (7) ◽

pp. 1874

Author(s):

Alberto Elmi ◽

Nadia Govoni ◽

Augusta Zannoni ◽

Martina Bertocchi ◽

Chiara Bernardini ◽

...

Keyword(s):

Gene Expression ◽

Correlation Analysis ◽

Roe Deer ◽

Capreolus Capreolus ◽

Reproductive Activity ◽

Melatonin Receptors ◽

Local Synthesis ◽

Testicular Weight ◽

And Function ◽

Gene Expression Levels

Roe deer are seasonal breeders with a complete yearly testicular cycle. The peak in reproductive activity is recorded during summer, the rutting period, with the highest levels of androgens and testicular weight. Melatonin plays a pivotal role in seasonal breeders by stimulating the hypothalamus–pituitary–gonads axis and acting locally; in different species, its synthesis within testes has been reported. The aim of this study was to evaluate the physiological melatonin pattern within roe deer testes by comparing data obtained from animals sampled during pre- and post-rut periods. Melatonin was quantified in testicular parenchyma, along with the genetic expression of enzymes involved in its local synthesis (AANAT and ASMT) and function (UCP1). Melatonin receptors, MT1-2, were quantified both at protein and gene expression levels. Finally, to assess changes in reproductive hormonal profiles, testicular dehydroepiandrosterone (DHEA) was quantified and used for a correlation analysis. Melatonin and AANAT were detected in all samples, without significant differences between pre- and post-rut periods. Despite DHEA levels confirming testicular involution during the post-rut period, no correlations appeared between such involution and melatonin pathways. This study represents the first report regarding melatonin synthesis in roe deer testes, opening the way for future prospective studies in the physiology of this species.

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Seasonal adiposity and androstenedione production as a possible mechanism for asynchronous reproductive activity between males and females of vespertilionid bat, Scotophilus heathi

Acta Biologica Hungarica ◽

10.1007/bf03542963 ◽

2000 ◽

Vol 51 (1) ◽

pp. 37-44

Author(s):

A. Krishna ◽

Abhilasha ◽

K. Singh

Keyword(s):

Reproductive Activity ◽

Males And Females

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Overfeeding Extends the Period of Annual Cyclicity but Increases the Risk of Early Embryonic Death in Shetland Pony Mares

Animals ◽

10.3390/ani11020361 ◽

2021 ◽

Vol 11 (2) ◽

pp. 361

Author(s):

Nicky M. M. D’Fonseca ◽

Charlotte M. E. Gibson ◽

Iris Hummel ◽

David A. van Doorn ◽

Ellen Roelfsema ◽

...

Keyword(s):

Embryo Transfer ◽

Reproductive Activity ◽

High Energy ◽

Morphometric Parameters ◽

Net Energy ◽

Conceptus Development ◽

And Control ◽

Annual Duration ◽

Embryonic Death

Obesity has been associated with altered reproductive activity in mares, and may negatively affect fertility. To examine the influence of long-term high-energy (HE) feeding on fertility, Shetland pony mares were fed a diet containing 200% of net energy (NE) requirements during a three-year study. The incidence of hemorrhagic anovulatory follicles (HAF) and annual duration of cyclicity were compared to those in control mares receiving a maintenance diet. Day-7 embryos were flushed and transferred between donor and recipient mares from both groups; the resulting conceptuses were collected 21 days after transfer to assess conceptus development. HE mares became obese, and embryos recovered from HE mares were more likely to succumb to early embryonic death. The period of annual cyclicity was extended in HE compared to control mares in all years. The incidence of HAFs did not consistently differ between HE and control mares. No differences in embryo morphometric parameters were apparent. In conclusion, consuming a HE diet extended the duration of cyclicity, and appeared to increase the likelihood of embryos undergoing early embryonic death following embryo transfer.

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Determination of Efficacy of Single and Double 4.7 mg Deslorelin Acetate Implant on the Reproductive Activity of Female Pond Sliders (Trachemys scripta)

Animals ◽

10.3390/ani11030660 ◽

2021 ◽

Vol 11 (3) ◽

pp. 660

Author(s):

Edoardo Bardi ◽

Martina Manfredi ◽

Raffaella Capitelli ◽

Emanuele Lubian ◽

Alessandro Vetere ◽

...

Keyword(s):

Phase Ii ◽

Egg Production ◽

Reproductive Activity ◽

Trachemys Scripta ◽

Phase Iii ◽

Control Group ◽

Sexual Hormones ◽

Significant Difference ◽

Group 6 ◽

Plasmatic Concentration

The use of long-acting gonadotropin-releasing hormone (GnRH) agonists to suppress fertility has been poorly investigated in reptiles, and the few available studies show inconsistent results. The efficacy of single and double intramuscular 4.7 mg deslorelin acetate implants in captive pond sliders (Trachemys scripta) was investigated, with 20 animals divided into three groups: a single-implant group (6 animals), a double-implant group (6 animals), and a control group (no implant). During one reproductive season (March to October), plasmatic concentration of sexual hormones (estradiol, progesterone, and testosterone) and ovarian morphometric activity via computed tomography were monitored about every 30 days. A significative decrease in the number of phase II ovarian follicles was detected in the double-implant group compared with the control group, but no significant difference was noted in the number of phase III and phase IV follicles, egg production, and plasmatic concentration of sexual hormones. Results show that neither a single nor a double deslorelin acetate implant can successfully inhibit reproduction in female pond sliders during the ongoing season, but the lower number of phase II follicles in the double-implant group can possibly be associated with reduced fertility in the following seasons.

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