Reproductive Anatomy and Physiology in the Male

Bravo, P. Walter

doi:10.1016/b978-1-4377-2352-6.00015-8

Cited by 5 publications

(8 citation statements)

References 22 publications

(20 reference statements)

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“…The largest increase was seen in the 13 to 14 month age group. This supports earlier observation that this is the stage of onset of puberty in some animals (3,34,38). An interesting observation in the present study is a drop in the response to hCG stimulation in the 15 to 16 month age group before increasing again after 17 months of age.…”

Section: Discussionsupporting

confidence: 92%

“…Data on testicular steroidogenesis in camelids is very limited. In alpacas, serum testosterone concentration is reported to be low until 9 months of age then increases rapidly starting at 11 months of age and reaches adult levels by 2 years of age (32,34). In camels, the pattern of testosterone section is strongly affected by season and diurnal rhythms particularly in rutting camels (35,36).…”

Section: Discussionmentioning

confidence: 99%

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Basal Levels and hCG Responses of Serum Testosterone and Estrogen in Male Alpacas

2020

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Steroid response to human Chorionic Gonadotropin (hCG) administration has been used in various species to study testicular function and for diagnostic purposes. In this study, two experiments were conducted to determine serum testosterone concentration response to administration of hCG and its correlation with testicular weight. In the second experiment the relationship between age, testosterone and estrogen response to hCG, and testicular histometry was in pre-pubertal and post-pubertal male alpacas. For experiment 1, males in two age groups (2 to 3 years, n = 9) and (4 to 7 years; n = 15) received 3,000 IU hCG IV, 36 to 48 h before castration. Serum testosterone concentration was determined before (T0), 1 h (T1), 2 h (T2), 8 h (T8), and 24 h (T24) after administration of hCG. Basal concentrations of serum testosterone was significantly different ( P < 0.01) between age groups. Serum testosterone concentrations increased over time and doubled 2 h after treatment. The highest change (250 to 300% increase from T0) was observed at 8 h (3.5 ± 0.3 ng/ml). A significant correlation ( P < 0.01; r = 0.64) was found between serum testosterone concentration and total testicular weight. For experiment 2, 60 males ranging in age from 6 to 60 months were used. Serum testosterone and estrogen was determined in samples taken just prior to and 2 h after administration of 3,000 IU hCG. Basal serum testosterone concentrations were very low (≤0.1 ng/mL) until 9 months of age then increased steadily with age. There was a significant variation amongst males within the same age group. Serum testosterone concentration increased by 2- to 4-fold 2 h after hCG injection ( P ≤ 0.05). Males in the 13 to 14 months of age group had the highest rise. Estrogen concentration increased in response to hCG administration and was detected only in males with high testosterone. We conclude that administration of 3,000 IU of hCG IV can be used reliably to detect testicular tissue and study its steroidogenic activity. The response is correlated with testicular weight and Leydig cell number. Testicular growth and sensitivity to LH stimulation increases between the ages of 13 and 14 months. The aromatizing ability of Leydig cells increased significantly in post-pubertal male alpacas.

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Section: Discussionsupporting

confidence: 92%

Section: Discussionmentioning

confidence: 99%

Basal Levels and hCG Responses of Serum Testosterone and Estrogen in Male Alpacas

2020

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“…37.1 % live sperm at early vs. later collection time points (10). In addition the testes of alpaca are relatively small given its body size, in comparison with other livestock (63).…”

Section: Discussionmentioning

confidence: 97%

Intra-horn insemination in the alpacaVicugna pacos: Copulatory wounding and deep sperm deposition

Brennan,

Purdy,

Bacon

2023

Preprint

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Alpacas (Vicugna pacos) are reported to be the rare mammal in which the penis enters the uterus in mating. To date, however, only circumstantial evidence supports this assertion. Using female alpacas culled for meat, we determined that the alpaca penis penetrates to the very tips of the uterine horns, abrading the tract and breaking fine blood vessels. All female alpacas sacrificed one hour or 24 hours after mating showed conspicuous bleeding in the epithelium of some region of their reproductive tract, including the hymen, cervix and the tips of each uterine horn, but typically not in the vagina. Unmated females showed no evidence of conspicuous bleeding. Histological examination of mated females revealed widespread abrasion of the cervical and endometrial epithelium, injuries absent in unmated females. Within one hour of mating, sperm were already present in the oviduct. The male alpaca’s cartilaginous penis tip with a hardened urethral process is likely responsible for the copulatory abrasion. The entire female reproductive tract interacts with the penis, functioning like a vagina. Alpacas are induced ovulators, and wounding may hasten delivery of the seminal ovulation-inducing factor beta-NGF into the female’s blood stream. There is no evidence of sexual conflict in copulation in alpaca, and thus wounding may also be one of a variety of mechanisms devised by mammals to induce a beneficial, short-term inflammatory response that stimulates blastocyst implantation, the uterine remodeling associated with placental development, and thus the success of early pregnancy.

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“…Although the application of some technologies in female SACs has increased in recent years (Table 1), according to Bravo (2014) andrological reports are rare. One reason for this could be the difficulty of collecting, handling and evaluating semen samples (Morton and others 2008, Bravo 2014, Stuart and others 2015). Despite the increase in ARTs, methods for successful embryo freezing are proving elusive.…”

Section: Characteristics Of South American Camelidsmentioning

confidence: 99%

“…Although the first report of AI use in camelids was by Fernández-Baca and Novoa (1968), use of this technique remains limited and insemination trials are infrequently reported (Skidmore and others 2013, Bravo 2014, Stuart and Bathgate 2015). This could be due to the difficulties in collecting and handling the semen (Skidmore and others 2013).…”

Section: Assisted Reproduction Technologies In Male South American Camentioning

confidence: 99%

Semen collection methods in alpacas

et al. 2017

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South American camelids, particularly alpacas, are gaining in popularity outside their native lands. Reproductive biotechnologies, such as artificial insemination or embryo transfer with cryopreserved embryos, are more complicated in these species than many others due to differences in their reproductive physiology compared to the more commonly encountered domestic livestock. This article reviews the methods currently available for obtaining semen or spermatozoa from alpacas and describes some of the problems associated with handling the viscous seminal plasma characteristic of camelids. Possibilities and limitations of reproductive biotechnologies in this species are discussed, and future developments are outlined, especially some new techniques which are currently being developed for use with camel semen and may be transferable to alpacas.

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Reproductive Anatomy and Physiology in the Male

Cited by 5 publications

References 22 publications

Basal Levels and hCG Responses of Serum Testosterone and Estrogen in Male Alpacas

Basal Levels and hCG Responses of Serum Testosterone and Estrogen in Male Alpacas

Intra-horn insemination in the alpacaVicugna pacos: Copulatory wounding and deep sperm deposition

Semen collection methods in alpacas

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