Theriogenology wild最新文献

Training is a management practice that should be used to facilitate routine care and management of animals. If well planned, training promotes human-animal interactions and enables the completion of veterinary procedures required for effective health assessment with lower stress levels. Hence, it is indicated whenever ancillary tests are needed. A captive adult female capybara (Hydrochoerus hydrochaeris) housed in a public research laboratory in the state of São Paulo, Brazil, was used in this study. The animal expressed aversion to some keepers and escape behavior in the presence of strangers. The animal was trained before mating to enable pregnancy ultrasound examination with no need for restraint until delivery. Fourteen weeks of training using three techniques (Counterconditioning, Habituation, and Operant Conditioning using shaping with positive reinforcement) were needed to achieve project objectives. The training enabled appropriate ultrasound imaging. Unique images with high diagnostic value were obtained throughout pregnancy, with significant contributions to the reproductive management of the species. Training is also an essential element of good management practices.

Cryopreservation and transplantation of testicular cells (TCs), especially spematogonial stem cells (SSCs), offers a new perspective for the genetic rescue of birds since traditional biobanking using semen and eggs are either inefficient or impractical. Here, we demonstrated that transplantation of TCs (which contained SSCs) from dead curassows were able to survive and colonize chicken testes, despite the phylogenetic distance between donors and recipients. Previously to transplants, TCs were collected, cryopreserved, thawed, and then labelled with PKH26. Subsequently, labelled TCs were transferred into gonads of sterilized recipient chickens, and monitored for their presence and development from 1 to 180 days after transplantation. The interval between collecting testes and processing them in the laboratory was crucial for TCs viability, but it did not affect the viability of undifferentiated spermatogonia within 24 hours post-mortem. Although positive correlation between testis weight and the total cells recovered was noticed, the number of undifferentiated spermatogonia comprised approximately 0.05% of the total TCs. Once the number of undifferentiated spermagonial stem cells was not sufficient, we decided to make transplants using crude TC fractions containing different types of germ and somatic cells. PKH26-positive cells were found in the cryosections of recipient testes until 42 days after transplantation, whereas the presence of the donor genomic DNA was confirmed until 120 days after transplantation. Taken together, our findings indicate that chicken testes can provide functional conditions for the survival and proliferation of germ cells rescued from individuals of another family of the Galliformes order. This approach represents a promising conservation tool for the recovery of testicular germ cells (including SSCs) from individuals of different ages (from embryos to adult males).

Spermatogenesis is a biological process that occurs inside the seminiferous tubules and results in the production of highly specialized cells, the spermatozoa. The Neotropical rattlesnake Crotalus durissus is a medical-importance snake species that presents a seasonal reproductive pattern. Here we characterized for the first time the spermatogenesis of a Neotropical snake species. Testes of 15 mature male specimens of C. durissus were evaluated. Through histomorphometry analyses was determined that around 94 % of the testis parenchyma is occupied by seminiferous tubules. Seminiferous epithelium in rattlesnake is composed of different generations of germ cells that are organized in eight stages of the seminiferous epithelium cycle (SEC). The sperm release occurs at stage II and a multi-stage pattern was observed in this species. Surprisingly, two rounded spermatids generations were present from stage I to IV. Using the proliferation cell marker BrdU (bromodeoxyuridine), the duration of spermatogenesis was calculated based on the most advanced germ cell labeled, which was established at 40.80 days. High efficiency of Sertoli cell associated with a short duration of SEC rendered a powerful sperm production observed for C. durissus. These features indicate a well-established adaptation of this species to reach an enormous number of gametes, which is one of the various mechanisms developed to guarantee survival and maintain the genes passing over the next generations.

Simple summary

All species have one main goal, which is to pass their genes over to the next generations. In order to do that, males and females produce specialized cells that combined, will allow the generation of a new life. The male gamete, the spermatozoon, is produced inside the testes in a process named spermatogenesis. Besides it has been described for many species, especially mammals, little is known regarding the spermatogenesis of snakes. Thus, the present study revealed that rattlesnakes’ spermatogenesis is such organized as in humans. While in other animals only one generation of rounded spermatids is part of the spermatogenic stage, in rattlesnakes were observed two generations of rounded spermatids present in 4 out of 8 stages of the seminiferous epithelium cycle. The existence of the extra generation of rounded spermatids results in approximately one additional cycle for spermatogenesis completion. However, the total duration of spermatogenesis, which means the time to produce the spermatozoa, still stands among the fastest ones, being around 41 days. Also, the additional germ cell population resulted in a high Sertoli cell support capacity. These parameters have a strong influence over the daily sperm production, which reaches more than 100 million spermatozoa per gram of testis.

Companion animals, non-domestic and endangered species (CANDES) encompass a group of animals that do not include traditional livestock species (cattle, pigs, sheep, goats). Historically, lack of commercial interest or need resulted in a lag in the development and application of assisted reproductive technologies (ARTs) in CANDES. A number of factors impeded progress, including the species-specific nature of reproductive biology and difficulties accessing research material. The past 25 years have seen a growth in cell-based technologies (stem cell derivation, genome editing), offering a new horizon of possibilities to the current state-of-the-art for assisted reproduction in CANDES. This review highlights some of the challenges and successes in working with these diverse species.

Despite dipping to perilously low numbers over the past century, all five rhinoceros (rhino) species still survive in the wild with four also in managed breeding programs. These managed populations have been essential for advancing rhino reproductive science and technology. Despite a plethora of challenges and the incremental nature of sound science, researchers have made significant progress over the past quarter century in broadening our knowledge of rhino reproduction, developing new technologies, and expanding the scope of existing research tools. When we compare the state of this scientific field a quarter century ago to where it stands today, there is much to celebrate. For example, at the turn of the century, the Sumatran rhino breeding program had failed to produce a single calf, the first rhino artificial insemination (AI) procedures had just been described, but no pregnancies had been documented, and in vitro fertilization (IVF) had not succeeded in any rhino species. As we reach the end of 2023, 8 Sumatran rhino calves have been born, a total of 17 white and greater one-horned rhino calves have been produced by AI, and 51 white rhino IVF embryos have developed into blastocysts. Furthermore, several theories based on the evidence available at that time have been disproven as additional scientific data have deepened our knowledge and understanding. However, many unanswered questions still exist, and reproductive technologies require refinement, development, or application to additional rhino species, so plenty of challenges remain on the landscape for future generations of rhino reproductive scientists to conquer.

The study of embryonic development in fish and how water temperature affects the life stage in this group is of pivotal importance to support works that aim at the conservation, management, and recovery of endangered or high economic valuable species. It allows a better evaluation of the species and the identification of morphophysiological changes related to the environmental factor in question. In addition, hybridization emerges as a biotechnological tool that may be applied as a technique for the creation of sterile animals that can be used as recipients for the germ cell transplantation approach, thus contributing to the conservation of different fish species. Based on this, we artificially reproduced two Amazonian fish species, Astyanax bimaculatus, and Moenkhausia oligolepis, and the resulting offspring of each species had their embryonic development followed at room temperature (25 °C) and at high temperature (30 °C). In addition, we performed interspecific crossbreeding between the species, and the offspring were also incubated and observed under the above conditions. The results showed that the high temperature accelerates the embryonic development of both, the offspring from A. bimaculatus and from hybridization. However, no larvae survived. Regarding M. oligolepis, the embryos did not develop, dying at 4:40 post-fertilization. For the hybridization, only the crossbreeding between females of A. bimaculatus and males of M. oligolepis resulted in normal larvae. They presented their own morphological characteristics, showing no total or partial characteristics from the parents, besides presenting atrophied and sterile gonads. Heat waters were proven to compromise the embryonic development of both Amazonian species. On the other side, the hybridization between those two Amazonian species has shown to be a tool with great potential for sterilization and the development of individuals suitable for use as surrogate breeders aiming for the ecological maintenance of various fish species.

This study describes the bone development during the intrauterine phase of the black agouti (Dasyprocta fuliginosa), discussing its relationship with the species’ adaptive strategies and comparing it with other precocial and altricial species. We analyzed 33 conceptuses (four embryos and twenty-nine fetuses) obtained through collaboration with local hunters in the Amazon. Mineralization measurements of the axial and appendicular skeletons were performed by ultrasonography using a 10–18 MHz linear transducer. The chronological order of occurrence of mineralization in relation to the total dorsal length (TDL) and to the percentage of the total gestational period (GP) was: skull, ribs, vertebral bodies, clavicle, scapula, humerus, radius, ulna, ilium, ischium, femur, tibia, and fibula (TDL = 8.2 cm, 48 % GP); metacarpi, metatarsi and pubis (TDL = 9 cm, 51 % GP); thoracic and pelvic limb phalanges (TDL = 13.2 cm, 65 % GP); carpus (TDL = 15.10 cm, 72 % GP) and distal row of tarsus (TDL = 19.6 cm, 87 % GP). Mineralization of the patella was not observed in any advanced fetus (fetus with> 80 % GP). Regarding secondary ossification centers, the first signs of mineralization were observed in the distal epiphysis of the radius, distal epiphysis of the femur, and proximal and distal epiphysis of the tibia (TDL = 13.2 cm, 65 % GP). Fetuses at birth (TDL > 21.5 cm, 93.5 % GP) showed mineralization in all primary centers, and in most secondary ossification centers. Black agouti neonates have a high level of precociality with well-developed skeletal system at birth, which promotes independent postnatal locomotion and dexterity to manipulate and forage in search of food. Our results can contribute to the monitoring of bone development in other wild species, providing parameters for the identification of gestational age and serving as a model for comparisons between precocial and altricial mammals, ultimately helping understand life history strategies in different species.