Development of in vitro embryo production systems for red deer (Cervus elaphus). Part 1. Effect of epithelial oviductal monolayers and heparin on in vitro sperm motility and penetration of in vitro matured oocytes

The Quality and Fertilizing Potential of Red Deer (Cervus elaphus L.) Epididymal Spermatozoa Stored in a Liquid State

The aim of this study was to assess the quality and fertilizing potential of red deer epididymal spermatozoa stored in a liquid state for up to 11 days (D11). In Experiment 1, sperm quality was determined. In Experiment 2, the efficiency of in vitro fertilization (IVF) and artificial insemination (AI) of stored sperm were evaluated. An analysis of sperm quality on D5 of storage revealed a decrease (p < 0.05) in motility and morphology, and a higher proportion of apoptotic spermatozoa. On D1, D7 and D10, the total motility of sperm for IVF and AI was determined to be 82.6%, 71.0% and 64.8%, respectively. The results of IVF and AI demonstrated that the fertilizing potential of spermatozoa differs between days of storage. The percentage of blastocysts was higher when oocytes were fertilized on D1 (17.4 %) compared to D7 (8.5%) and D10 sperm (10.5%). Differences were noted in the pregnancy rates of inseminated hinds. The insemination with D1, D7 and D10 sperm led to live births (33% from D7 and D10). The results indicate that the quality of red deer epididymal spermatozoa remains satisfactory during ten days of storage in a liquid state, and that these spermatozoa maintain their fertility potential.

Artificial Reproductive Technology (ART) Applied to Female Cervids Adapted from Domestic Ruminants

There are about 150 Cervidae species on the IUCN Red List of Threatened Species. Only a small part is counted among farm animals, and most of them are free roaming. The universality and large numbers of representatives of cervids such as red deer (Cervus elaphus) and roe deer (Capreolus capreolus) may predispose these species to be used as models for research on reintroduction or assisted reproduction of deer at risk of extinction. We outlined the historical fluctuation of cervids in Europe and the process of domestication, which led to breeding management. Consequently, the reproductive techniques used in domestic ruminants were adapted for use in female deer which we reviewed based on our results and other available results. We focused on stress susceptibility in cervids depending on habitat and antropopression and proposed copeptin as a novel diagnostic parameter suitable for stress determination. Some reproductive biotechniques have been adopted for female cervids with satisfactory results, e.g., in vitro fertilization, while others still require methodological refinement, e.g., cryopreservation of oocytes and embryos.

Understanding sperm physiology: Proximate and evolutionary explanations of sperm diversity

Much can be gained from the comprehensive study of a biological system. Based on what is known as Mayr's proximate-ultimate causation and the subsequent expansion to Tinbergen's four questions, biological traits can be understood by taking into account different approximations that try to explain mechanisms, development, adaptive significance or phylogeny. These, in principle, separate areas, can be integrated crossing boundaries, but bearing in mind that answers to one question would not explain a different query. Studies of sperm biology have, until now, not benefited much from this framework and potential integration. Proximate causes (particularly mechanisms) have been the subject of interest for reproductive biologists, and evolutionary explanations have been the domain of behavioural ecologists with interest in adaptive significance of traits in the context of post-copulatory sexual selection. This review will summarize opportunities for research in the different areas, focusing on sperm preparation for fertilization and suggesting possible integration within and between proximate and evolutionary studies.

Post-mortem recovery, in vitro maturation and fertilization of fallow deer (Dama dama, Linnaeus 1758) oocytes collected during reproductive and no reproductive season

Habitat degradation leads to small and fragmented populations, lower genetic variability and fertility overtime. Assisted reproductive techniques represent important tools to cope with the dramatic loss of biodiversity. Fallow deer (Dama dama), beyond its high commercial value and wide distribution, may represent the most suitable model to study endangered cervids. In this study, oocytes were recovered post-mortem from fallow deer during the breeding and no breeding seasons and were in vitro matured (IVM). The ability of cryopreserved thawed sperm samples recovered by electroejaculation from four adult males was tested by in vitro fertilization of IVM oocytes. The number of oocytes collected per ovary did significantly vary across seasons from 6.2 ± 0.92 during breeding season to 10.4 ± 1.26 during no breeding season (p = .006). Oocytes collected during the breeding season showed higher in vitro fertilization rate compared to the no breeding season (p = .045). However, no embryos reached the blastocyst stage. Semen samples obtained by electroejaculation were successfully cryopreserved, although the cryopreservation process negatively affected most kinetic parameters, mainly at 2 hr post-thawing. Moreover, the percentage of rapid spermatozoa significantly decreased between fresh samples and at 2 hr post-thawing, whereas the percentage of slow spermatozoa increased across the same period (p < .05). Our study provides the logistic steps for the application of assisted reproductive techniques in fallow deer and might be of great interest for genetic resource bank planning.

Selection of red deer spermatozoa with different cryoresistance using density gradients

The objective of sperm selection media is selecting the best spermatozoa and to remove seminal plasma and diluent for using them in assisted reproductive techniques. It is known that individuals show different cryoresistance in response to the same freezing procedure. Our hypothesis was that the efficacy of selection media could be dissimilar for samples with different sperm quality after thawing. Epididymal sperm samples from mature Iberian red deer were collected and frozen. Males were classified as with high post-thaw sperm quality when sperm motility (SM) ≥ 70%, or as with low post-thaw sperm quality when SM ≤ 69%. Samples were centrifuged using the following density gradients (DG): Percoll^® , Puresperm^® and Bovipure^™ , and several functional sperm parameters were assessed after sperm selecting and washing. Males classified with high sperm quality had higher post-thawing values (p > .05) for all parameters evaluated, except for linearity index, than those categorized as low sperm quality. After selection, some sperm characteristics improved (viability, apoptosis and mitochondrial activity) for both groups, showing the males with high sperm quality higher values in all sperm parameters except for kinematic traits and DNA fragmentation index (%DFI), regardless of DG. Bovipure^™ yield lower values of sperm motility, viability, apoptosis and mitochondrial activity in relation to Percoll^® and Puresperm^® considering both quality groups. There was an interaction between the type of DG and sperm quality group for sperm viability (p = .040) and apoptosis (p = .003). Thus, Percoll^® selected less live and more apoptotic spermatozoa than Puresperm^® and Bovipure^™ for males with low sperm quality. In conclusion, the DG are more efficient selecting spermatozoa from samples with high sperm quality, acting differently depending on initial sperm quality.

Alterations to the bull sperm surface proteins that bind sperm to oviductal epithelium

Three Binder of SPerm proteins (BSP1, BSP3, BSP5) are secreted by bovine seminal vesicles into seminal plasma and adsorbed onto sperm. When sperm inseminated into the female reach the oviduct, the BSP proteins bind them to its epithelial lining, forming a sperm storage reservoir. Previously, we reported that binding of capacitated sperm to oviductal epithelium in vitro is lower than that of uncapacitated sperm and we proposed that reduced binding was due to loss of BSP proteins during capacitation. Because of differences in amino acid sequences, we predicted that each BSP would respond differently to capacitating conditions. To test whether all three BSP proteins were lost from sperm during capacitation and whether the kinetics of loss differed among the three BSP proteins, ejaculated bull sperm were incubated under various capacitating conditions, and then the amounts of BSP proteins remaining on the sperm were assayed by Western blotting. Capacitation was assayed by analysis of protein tyrosine phosphorylation. While loss of BSP1 was not detected, most of the BSP5 was lost from sperm during incubation in TALP medium, even without addition of the capacitation enhancers heparin and dbcAMP-IBMX. Surprisingly, a smaller molecular mass was detected by anti-BSP3 antibodies in extracts of incubated sperm. Its identity was confirmed as BSP3 by mass spectrometry, indicating that BSP3 undergoes modification on the sperm surface. These changes in the composition of BSP proteins on sperm could play a role in releasing sperm from the storage reservoir by modifying sperm interactions with the oviductal epithelium.

In vitro maturation of dromedary (Camelus dromedarius) oocytes: effect of different protein supplementations and epidermal growth factor*

The present experiment was aimed to compare the effect of different protein supplementation sources, foetal calf serum (FCS), oestrous dromedary serum (EDS) and BSA, in experiment 1, and the effect of different concentrations of epidermal growth factor (EGF), in experiment 2, on in vitro nuclear maturation of the dromedary oocytes. Cumulus oocyte complexes (COCs) were harvested from the ovaries collected from a local slaughterhouse by aspirating the visible follicles in PBS supplemented with 5% FCS. Pooled COCs were randomly distributed to 4-well culture plates containing 500 μl of the maturation medium and cultured at 38.5 °C in an atmosphere of 5% CO(2) in air for 32-36 h. The basic maturation medium consisted of TCM-199 supplemented with 0.1 mg/ml L-glutamine, 0.8 mg/ml sodium bicarbonate, 0.25 mg/ml pyruvate, 50 μg/ml gentamicin, 10 μg/ml bFSH, 10 μg/ml bLH and 1 μg/ml estradiol. In experiment 1, this medium was supplemented with 10% FCS, 10% EDS or 0.4% BSA, whereas in experiment 2, it was supplemented with 0.4% BSA and 0, 10, 20 or 50 ng/ml of EGF. The oocytes were fixed, stained with 1% aceto-orcein stain and their nuclear status was evaluated. Oocytes were classified as germinal vesicle, diakinesis, metaphase-I, anaphase-I (A-I), metaphase-II (M-II) and those with degenerated, fragmented, scattered, activated or without visible chromatin as others. There was no difference (p > 0.05) observed in the proportion of oocytes reaching M-II stage between the media supplemented with FCS (71.5 ± 4.8), EDS (72.8 ± 2.9) and BSA (72.7 ± 6.2). In experiment 2, a higher proportion (p < 0.05) of oocytes reached M-II stage when the medium was supplemented with 20 ng/ml of EGF (81.4 ± 3.2) when compared with the media supplemented with 10 ng/ml (66.9 ± 4.1) and control (67.2 ± 7.1) groups. It may be concluded that the maturation media for dromedary camel oocytes can be supplemented with any of the three protein sources, i.e. FCS, EDS and BSA without any significant differences on the maturation rates. Also, a supplementation of 20 ng/ml of EGF in the maturation medium seems to be optimal and improves the nuclear maturation of dromedary camel oocytes.

The temporal relationship between oocyte maturation and early fertilisation events in relation to the pre-ovulatory LH peak and preimplantation embryo development in red deer (Cervus elaphus)

The temporal relationships among oocyte maturation, gamete transport and fertilisation following the pre-ovulatory luteinsing hormone surge in red deer were established; and secondly, early preimplantation development to the blastocyst stage in relation to the onset of oestrus was determined for red deer. In the first series of observations, oestrus was synchronised in April (N=22), for the fixed time recovery of gametes from 0 to 36 h after the estimated pre-ovulatory LH peak. Matings were observed and the time of the LH peak was determined from the retrospective analysis of blood plasma collected at 3h intervals. Gametes were recovered surgically and the meiotic status of follicular and ovulated oocytes assessed. Spermatozoa were recovered from the oviduct and their motility analysed by videomicroscopy. Nineteen of 22 hinds exhibited a pre-ovulatory LH surge and were observed to mate. Oocyte metaphase I occurred between 11 and 18 h, and metaphase II was completed within the follicle between 20 and 25 h following the pre-ovulatory LH peak. Fertilised ova were recovered from 30 to 36 h in both the ampulla and isthmic portions of the oviduct. Motile spermatozoa were first recovered from the isthmus and the ampulla at 13 and 21 h, respectively, after the LH peak. Hyperactive spermatozoa were observed in both the isthmus and the ampulla flushings but only from the eight hinds that had ovulated. In the second series of observations, 16 mature hinds were synchronised and allocated to groups for embryo collection on days 3, 5 and 7 after oestrus. Eight embryos were recovered; an 8-cell at 90 h, 3 morulae at 137, 138 and 186 h, and 4 blastocysts at 180, 182 and 190 h post-mating. Blastocysts were only recovered from the uterine horns and the mean+/-S.E.M. number of nuclei per blastocyst was 93.5+/-10.0 with a range of 66-114 cells. The results of this study will improve the application of assisted reproductive technologies to red deer as they indicate that oocyte maturation, fertilisation and early embryonic development of the red deer is similar to other domestic ruminants with the exception that the red deer embryo enters the uterus at the blastocyst stage.

Laparoscopic ovum pick-up and in vitro production of sika deer embryos: effect of season and culture conditions

Amongst the 200 deer subspecies worldwide, more than 40 are considered as endangered. In vitro embryo production may represent an efficient way to produce and disseminate offspring from sparse remaining individuals in these species. With a view to establishing a method of in vitro embryo production, we assessed the ovarian response after hormonal stimulation (oFSH), oocyte yield following laporoscopic ovum pick-up (LOPU) and oocyte developmental competence according to seasonal reproductive status in sika deer (Cervus nippon nippon). Twelve adult sika deer hinds were allocated between two groups and submitted weekly to oFSH follicular growth stimulation followed by LOPU. Hinds in Group A (n=6) were treated first during the breeding season (5 weeks), and then during the non-breeding season (3 weeks). Hinds in Group B (n=6) were submitted to similar procedures but in the reverse order (treated first during the non-breeding season). Cumulus-oocytes complexes (COC) recovered from Group B were allowed to mature in vitro for 24 h in TCM-199 medium supplemented with oFSH, goat follicular fluid and 100 microM cysteamine. In vitro fertilization was performed with frozen/thawed semen in SOFaa medium supplemented with 20% estrous sheep serum and presumptive zygotes were cultured in the presence or absence of ovine oviductal epithelial cell monolayer (oOEC) in SOFaa-BSA medium. Mean number of follicles aspirated per hind per session decreased significantly between breeding and non-breeding season in Group A (9.8+/-0.7 versus 3.2+/-0.7, mean+/-S.E.M., respectively, P<0.001) but did not change between the non-breeding and the subsequent breeding season in Group B (5.3+/-0.7 and 5.7+/-0.7, respectively, P>0.05). Irrespective of the season, good quality COC with complete and compact cumulus investments were recovered allowing a high cleavage rate after in vitro maturation and fertilization. Whereas development to the blastocyst stage did not occur in SOF medium alone, high development rates to the blastocyst stage were observed in oOEC co-culture regardless of season (22% and 34% of total oocytes in co-culture during non-breeding and breeding season, respectively).

Successful use of oviduct epithelial cell coculture for in vitro production of viable red deer (Cervus elaphus) embryos

Techniques for in vitro production (IVP) of viable embryos have been thoroughly developed in several domestic species in view to improve breeding efficiency. When applied to wild life, these techniques may also help the maintenance of biodiversity through amplification of sparse animals offspring and facilitation of genetic material exchange. During the successive steps of IVP, i.e. oocyte in vitro maturation (IVM), fertilization (IVF) and early embryo development (IVD) to the blastocyst stage, gametes and embryos are faced with unusual environment, including oxidative stress, known to be detrimental to their survival. In the present study, starting from methods developed in domestic species, we have adapted IVP to produce viable red deer embryos. In a first experiment, cumulus cells were removed from in vitro matured oocytes either before or after IVF. The presence of cumulus cells during IVF did not affect final cleavage or development rates. In a second experiment, in vitro matured oocytes were fertilized in the presence of cumulus cells and cultured in SOFaaBSA medium alone or in the presence of ovine oviduct epithelial cell (oOEC) monolayer. Whereas, oviduct cells did not improve the cleavage rate, they significantly increased the rate of embryos reaching the blastocyst stage (from 3 to 25% of total oocytes). Ten blastocysts from oOEC coculture were transferred after freezing and thawing to five recipient hinds and gave rise to three pregnancies. The three pregnant hinds gave birth to three live and normal calves.

Kinetics of nuclear maturation and effect of holding ovaries at room temperature on in vitro maturation of camel (Camelus dromedarius) oocytes

Experiments were conducted to investigate kinetics of in vitro nuclear maturation and the effect of storing ovaries at room temperature on initial chromatin configuration and in vitro maturation of dromedary camel oocytes. Cumulus oocyte complexes (COCs) were collected from slaughterhouse ovaries and matured in vitro for 4-48h. At every 4h interval (starting from 0 to 48 h), groups of oocytes were fixed, stained and evaluated for the status of nuclear chromatin. Oocytes were categorized as germinal vesicle (GV), diakinesis (DK), metaphase-I (M-I), anaphase-I (A-I), metaphase-II (M-II) stage and those with degenerated, fragmented, activated or without a visible chromatin as others. At the start of culture, 74% (66/89) oocytes were at GV stage, 13% (12/89) at DK and 12% (11/89) were classified as others. Germinal vesicle breakdown started spontaneously in culture and at 20 h of culture 97% oocytes had already completed this process. After 8 and 16 h of maturation the highest proportion of oocytes (42%, 48/114 and 41%, 51/123) were at DK and M-I stage, respectively. The proportions of oocytes reaching M-II stage at 32 (42%, 50/118), 36 (45%, 47/104), 40 (49%, 57/117), 44 (52%, 103/198) and 48 h (46%, 55/120) of culture were not different from each other (P>0.05). The proportion of oocytes categorized as others, however, increased after 40 h of culture and was higher (P<0.05) at 48 h compared with other maturation periods. There was no difference (P>0.05) in the proportion of oocytes reaching M-II stage from the ovaries collected and stored in normal saline solution (NSS) at room temperature for 12h (43%, 64/148) and those collected in warm NSS (37 degrees C) and processed immediately after arrival in laboratory (49%, 57/117). However, low number of oocytes reached M-II stage from ovaries collected in warm NSS but stored at room temperature (29%, 37/128) compared with other two groups (P<0.05). It may be concluded that dromedary oocytes require 32-44h of in vitro culture to have an optimum number of oocytes in M-II stage. However, further studies are required to find out the most appropriate maturation period, which will result in the further development of these oocytes after IVF, ICSI, parthenogenetic activation or nuclear transfer. Ovaries can be collected and stored in normal saline solution at room temperature for 12h without any appreciable effect on the nuclear maturation of the oocytes.

The effect of harvesting technique on efficiency of oocyte collection and different maturation media on the nuclear maturation of oocytes in camels (Camelus dromedarius)

The purpose of this investigation was to develop an efficient method for harvesting oocytes from dromedary camel ovaries and to examine the effect of different maturation media on their subsequent maturation in vitro. Oocytes were collected by aspirating the follicular contents using a needle attached to a syringe (Method I, n=163 ovaries) or to a constant aspirating pressure, applied by a vacuum pump (Method II, n=117 ovaries). Individual follicles were excised from ovaries and follicles were punctured with two needles (Method III, n=117). Oocytes were matured in vitro for 40-42 h. At the end of maturation period, oocytes were denuded of cumulus cells and the proportion of oocytes in metaphase-II (MII) stage was determined. In the second experiment, oocytes collected by the dissection method were matured in Tissue Culture Medium199 (TCM), CR1 or modified Connaught Medical Research Laboratories medium-1066 (CMRL) and their nuclear maturation was evaluated after 40-42 h. The recovery rate of oocytes was higher (P<0.01) with Method III compared with Method I or II (94, 31 and 33%, respectively). A higher proportions of oocytes collected with Method I or II were either completely or partially denuded compared with Method III (31, 14% versus 1%). The proportions of viable oocytes (78, 60 and 70%, respectively) and those showing metaphase II was not different (39, 50 and 46%, respectively, P>0.05) among the three treatment groups. Oocyte maturation rate was higher (P<0.05) when TCM was used compared with CMRL or CR1 medium. There was, however, no difference in the maturation rate for oocytes cultured in CMRL or CR1 medium. It may be concluded that a higher proportion of cumulus enclosed oocytes may be recovered by follicle dissection method compared to aspiration using syringe or pump. The higher recovery rate with a comparable proportion of viable and matured oocytes resulted in the overall increase in the number of matured (MII) oocytes/ovary with follicle dissection procedure compared with aspiration procedures. For in vitro maturation of oocytes, TCM is superior to CR1 and CMRL as basic maturation medium for this species.

New developments reproductive technologies in deer

In vitro embryo production is the platform for advanced reproductive technologies, such as cloning. The in vitro embryo production system developed for farmed red deer (Cervus elaphus) evolved along similar lines to that pioneered by other domestic species researchers. However, applying existing in vitro embryo production methods from these other species resulted in limited success and has necessitated developing a species-specific methodology for red deer based on the their physiology. Analysis of oviduct fluid led to the development of a semi-defined fertilization and culture media system, Deer Synthetic Oviduct Fluid (DSOF), which resulted in successful culture of red deer embryos to the blastocyst stage. Transvaginal ultrasound-guided ovarian examination and ovum pickup has enabled the study of seasonality constraint and propagation from selected female genetics, respectively. During the 4-month breeding season (April-July), 15% of cleaved oocytes developed to blastocysts, whereas no blastocysts developed from oocytes collected after July. The process of developing an in vitro embryo production system for farmed red deer may serve as a beneficial model for the propagation of endangered cervine species.

New commercial opportunities for advanced reproductive technologies in horses, wildlife, and companion animals

As advanced reproductive technologies become more efficient and repeatable in livestock and laboratory species, new opportunities will evolve to apply these techniques to alternative and non-traditional species. This will result in new markets requiring unique business models that address issues of animal welfare and consumer acceptance on a much different level than the livestock sector. Advanced reproductive technologies and genetic engineering will be applied to each species in innovative ways to provide breeders more alternatives for the preservation and propagation of elite animals in each sector. The commercialization of advanced reproductive techniques in these niche markets should be considered a useful tool for conservation of genetic material from endangered or unique animals as well as production of biomedical models of human disease.

Development of in vitro embryo production systems for red deer (Cervus elaphus). Part 3. In vitro fertilisation using sheep serum as a capacitating agent and the subsequent birth of calves

The following experiments investigated the use of sheep serum (SS) as a capacitating agent for red deer (Cervus elaphus) sperm during in vitro fertilisation. Red deer oocytes were collected at slaughter and matured in vitro for 24h in TCM-199 supplemented with 10% foetal calf serum, 10 microg ml(-1) FSH and LH, and 1microg ml(-1) of oestradiol. Fertilisation medium was IVF-SOF modified to contain 5mM Ca(2+) and no glucose. Experiment 1 investigated the addition of heparin, BSA (8 mg ml(-1)) or 20% SS. All oocytes were penetrated when IVF-SOF was supplemented with SS compared to 10 and 0% penetration when either heparin or BSA was present (P<0.01). However, 43.8% of these oocytes were polyspermic when the medium contained SS. In Experiment 2, the effect of sperm concentration on penetration rates during in vitro fertilisation was investigated. Total sperm penetration and monospermic penetration rates increased with increased sperm concentrations in a log linear manner (P<0.001) and both approached an asymptote at 0.4 x 10(6) sperm ml(-1) with 93.6 and 77% for total and monospermic penetration, respectively. Polyspermic fertilisation also increased with increasing sperm concentrations (P<0.05) but was variable (range 3.5+/-4.2 to 42.3+/-10.6%), especially at the lower sperm concentrations. Experiment 3 investigated the viability of these oocytes after transfer into red deer recipients. Fifteen 2- and 4-cell embryos were transferred into the oviducts of synchronized recipients 28 h post in vitro insemination. An additional fourteen embryos (8-10 cell) were transferred into synchronised recipients after 48 h of in vitro culture in either SOFaaBSA (n=10) or on red deer epithelial oviduct monolayers (n=4). Five (33% 5/15) of the recipients that received 2- and 4-cell embryos were pregnant at Day 45 (verified by ultrasonography) and four recipients subsequently calved. One recipient receiving an embryo cultured in SOFaaBSA was pregnant at Day 45 and subsequently calved. The birth of five normal calves indicate that full developmental competence of red deer oocytes matured and fertilised in vitro can be achieved by the techniques described.