Reproductive anatomy, manipulation of ovarian activity and non-surgical embryo recovery in suni (Neotragus moschatus zuluensis)

Spontaneous embryonic death in plains viscacha (Lagostomus maximus - Rodentia), a species with unique reproductive characteristics

Spontaneous embryonic death is a conserved reproductive event in Eutherians. The macro and microscopic characteristics of this type of death are similar between the different taxa. However, in the hystricomorphic rodent plains viscacha (Lagostomus maximus) is exceptional in terms of massiveness (80% embryonic resorption). In this species, of the 10-12 implantation sites (IS) (half in each uterine horn), only the caudal embryos will survive, resorbing the cranial and intermediate IS. We hypothesize that uterine structural variations in L. maximus restrict growth and promote embryo death, with the consequent loss of placental homeostasis in the cranial and middle IS. In this study, different studies (ultrasonography, macroscopy and microscopy) were carried out to analyze different aspects of the intermediate gestation of L. maximus (46 days postcoitus). Ultrasonographic studies revealed that the cranial and middle IS (IS-1, IS-2, and IS-3) had no recognizable embryonic and placental structures as compared to the caudal implantation sites (IS-4). Macroscopically, the areas corresponding to the embryos in the cranial and middle IS were occupied by a necrotic black semi-fluid mass. Moreover, the placenta in these IS was undifferentiated. However, in the caudal IS both the embryo and its placenta were distinguishable. Using histological and immunohistochemical techniques, it was observed that the placentas of IS-1, IS-2 and IS-3 were disorganized and showed hemorrhage, inflammatory infiltration containing neutrophils, macrophages, mast cells and foreign body giant cells, apoptotic trophoblast, and a layer of collagen fibers and fibroblasts that circumscribed each of these IS. In contrast, the placenta of the caudal IS showed an organized maternal-embryonic interface. The characteristics observed in IS in resorption of viscachas in intermediate gestation show that, regardless of gestation time, embryonic death has a similar macro and microscopic morphological pattern among eutherians with invasive placentation. However, the massiveness and sectorization of embryonic death in the plains viscacha make the species a unique model for the study of this reproductive event.

Evolution of placentation in cattle and antelopes

Bovids have enjoyed great evolutionary success as evidenced by the large number of extant species. Several important domestic animals are from this family. They derive from both subfamilies: cattle and their kin belong to Bovinae and sheep and goats to Antilopinae. The premise of this review, therefore, is that evolution of reproduction and placentation is best understood in a context that includes antelope-like bovines and antelopes. Many key features of placentation, including hormone secretion, had evolved before bovids emerged as a distinct group. Variation nevertheless occurs. Most striking is the difference in fusion of the binucleate trophoblast cell with uterine epithelium that yields a transient trinucleate cell in bovines and many antelopes, but a more persistent syncytium in wildebeest, sheep and goat. There is considerable variation in placentome number and villus branching within the placentome. Many antelopes have right-sided implantation in a bicornuate uterus whilst others have a uterus duplex. Finally, there has been continued evolution of placental hormones with tandem duplication of PAG genes in cattle, differences in glycosylation of placental lactogen and the emergence of placental growth hormone in sheep and goats. The selection pressures driving this evolution are unknown though maternal-fetal competition for nutrients is an attractive hypothesis.

Placentation and hormonal maintenance of pregnancy in the impala (Aepyceros melampus)

INTRODUCTION

The impala is a widely distributed African ungulate. Detailed studies of the placenta and ovaries in impala undertaken in the 1970s did not address the endocrine functions of the placenta.

METHODS

The uteri of 25 pregnant impala estimated to be between 49 and 113 days of the 190 day gestation were examined grossly, histologically and immunohistochemically.

RESULTS

A single corpus luteum was present in either maternal ovary but the conceptus was always situated in the right uterine horn. The fetal membranes extended to the tips of both uterine horns. The amnion was in intimate contact with, but not fused to, the allantochorion. Placentation was typically ruminant with fetal macrocotyledons attached to the rows of maternal caruncles. The fetal villi were highly branched, especially in the centre of each placentome where the attenuated maternal epithelium lining the placental crypts was absent in some places. Both the corpus luteum and the uninucleate trophoblast cells of the interplacentomal allantochorion stained strongly for 3-β hydroxysteroid dehydrogenase, and progestagen concentrations in allantoic and amniotic fluids increased significantly as gestation progressed, with a tendency to do likewise in maternal serum. Binucleate trophoblast cells stained positively for bovine placental lactogen, but neither the placenta nor the maternal corpus luteum showed evidence of oestrogen synthesis.

DISCUSSION

Despite exhibiting the same basic type of placentation, both the gross and histological structure of the impala placenta, along with its immunohistochemical properties, demonstrates that great variation exists across ruminant placentas.

Noninvasive measurements of ovarian activity in Beira antelope (Dorcatragus megalotis)

As the natural habitat of more and more species becomes depleted, captive breeding programmes have become established to bring species back from the brink of extinction. Monitoring the reproductive status of an individual is essential in order to improve breeding success. Traditional methods have involved stressful blood sampling, and thus noninvasive methods have been proven to be reliable alternatives for monitoring reproductive function in both captive and free-ranging animals. Subsequently, noninvasive methods have become an invaluable tool in longitudinal studies and conservation efforts, as animals can be observed without, or minimal human contact. The Beira antelope is a small antelope endemic to the northern part of the Horn of Africa. Population numbers of the Beira have been declining over the last few decades due to habitat fragmentation. We show here that the reproductive cycle of female Beira antelopes can be monitored noninvasively, by using faecal samples to analyse oestrogen (fEM) as well as progestagen (fPM) metabolites. The profiles of fPM and fEM of both females showed regular cyclic patterns in which the follicular and luteal phases could be distinguished. The overall mean cycle length is 22 days (range: 21-25 days), with a mean length of the follicular phase of 6 days (range: 4-7 days) and a mean length for the luteal phase being 15 days (range: 12-16 days). The suitability of these noninvasive techniques should assist in optimizing breeding efforts of this endemic small antelope in captivity. Being noninvasive, this method could also be a useful tool for monitoring reproductive function in the dwindling wild populations.

Endocrine patterns of the estrous cycle and pregnancy of wildebeest in the Serengeti ecosystem

Despite the importance of the western white-bearded wildebeest (Connochaetes taurinus mearnsi) to the Serengeti-Mara ecosystem, surprisingly little is known about the reproductive physiology of this keystone species. A longitudinal, non-invasive endocrine study was conducted on female wildebeest captured from the Serengeti-Mara migration and maintained for approximately 16 months in large fenced enclosures within the species' natural range. An intact bull was introduced to a female subgroup (n=5), while remaining females (n=10) were unexposed to a male. Fecal progestagen patterns reflected ovarian activity and pregnancy. In non-pregnant animals, luteal and inter-luteal baseline progestagen values differed (p<0.001) over time, thereby allowing identification of recurrent estrous cycles. The average durations of the luteal phase, estrous cycle, gestation, and post-partum anestrus were 14.3+/-0.5, 22.6+/-1.0, 240.8+/-11.7, and 104.1+/-15.6 d, respectively. Annual reproductive patterns indicated a distinctive period of ovarian activity that extended from 13 May through 3 December (203.5+/-29.9 d) with all unmated females displaying from one to 14 estrous cycles. Progestagens were higher (p <0.001) in pregnant (n=4) than non-pregnant (n=10) cows. These data (1) reveal the value of fecal hormone monitoring for establishing the first ever endocrine profiles of female wildebeest in semi-free-living conditions in their native range, and (2) indicate that the species is a seasonal breeder that is polyestrous and a spontaneous ovulator.

A perspective on the role of emerging technologies for the propagation of companion animals, non-domestic and endangered species

Assisted reproductive technologies (ART) have been used successfully in humans, domestic and laboratory species for many years. In contrast, our limited knowledge of basic reproductive physiology has restricted the application of ART in companion animal, non-domestic and endangered species (CANDES). Although there are numerous benefits, and in some cases a necessity, for applying ART for the reproductive and genetic management of CANDES, the challenges encountered with even the most basic procedures have limited the rate of progress. In this foreword we discuss the status of conventional ART, such as artificial insemination and in vitro fertilisation, as well as their benefits and inherent difficulties when applied to CANDES. It is upon these techniques, and ultimately our knowledge of basic reproductive physiology, that the success of emerging technologies, such as those described in this special issue, are dependent for success.

Birth of live Spanish ibex (Capra pyrenaica hispanica) derived from artificial insemination with epididymal spermatozoa retrieved after death

As a consequence of increasing limitations to maintaining genetic variability in endangered wildlife species, methods of assisted reproduction widely used in domestic animals are being applied to nondomestic species. However, practical efforts have met limited success to date. The Spanish ibex (Capra pyrenaica hispanica) is a wild caprine originating exclusively in the mountains of Spain. This study was designed to evaluate the fertilizing capability of cryopreserved Spanish ibex epididymal spermatozoa recovered postmortem. For this purpose, we have previously evaluated the effect of time elapsed between death and sperm recovery on spermatic parameters, and the fertilization ability of frozen-thawed spermatozoa using heterologous in vivo fertilization by intrauterine insemination in domestic goat (Capra hircus). The time of death significantly affected most sperm quality parameters (motility, viability and intact acrosomes). The fertility obtained by heterologous artificial insemination was 18.7%, and only goats inseminated with spermatozoa recovered within 8h after death became pregnant. Our findings showed that heterologous in vivo fertilization is a useful method to evaluate the fertilizing capacity of sperm samples in rare or wild species. Sperm samples, with verified fertilization ability in the previous trial, were used to inseminate a total of six ibex females. Inseminations resulted in one pregnancy. The study demonstrated for the first time the feasibility of applying artificial insemination in Spanish ibex.

Postthaw Evaluation of In Vitro Function of Epididymal Spermatozoa from Four Species of Free-Ranging African Bovids1

An improved understanding of reproductive physiology in nondomestic bovids is necessary for the development of assisted reproductive technologies (ARTs) for use in the conservation of endangered bovids. In this study, epididymal spermatozoa were recovered from blesbok (Damaliscus dorcas phillipsi), African buffalo (Syncerus caffer), springbok (Antidorcas marsupialis), and black wildebeest (Connochaetes gnou) following organized culls in South Africa. Our objectives were 1) to characterize the quality of epididymal spermatozoa, 2) evaluate the effectiveness of a cryopreservation protocol, and 3) compare postthaw sperm longevity (motility, viability, and acrosomal integrity) and functionality in two culture media with two capacitation reagents (caffeine and heparin). Following recovery, spermatozoa were diluted in EQ extender, slow-cooled, and frozen in the presence of 5% glycerol. Thawed spermatozoa were separated on a Percoll gradient and diluted in fertilization media (SOF for fertilization [SOFfert]; 0.6% BSA, 0.0 mM glucose, 25.0 mM NaHCO(3)) or modified SOFfert (1.2% BSA, 1.5 mM glucose, 37.0 mM NaHCO(3)) and either heparin or caffeine, and incubated for 6 h. Spermatozoa from these species maintained an average of 64% initial motility after thawing. Incubation medium and capacitation reagent had species-specific effects on the motility, viability, and acrosomal integrity of spermatozoa, suggesting ART procedures need to be optimized for each species. Springbok spermatozoa were also shown to be competent for in vitro fertilization. Information from this study concerning sperm physiology in blesbok, African buffalo, springbok, and black wildebeest will be useful in the development of ART for the conservation of these and other species of bovids.

Importance of assisted reproductive technologies in the conservation of wild, rare or indigenous ungulates: review article

Biodiversity is increasingly threatened by intensive agriculture, environmental pollution, extinction of natural habitats and several other factors. Several mammalian species including ungulates have disappeared or are threatened by extinction. However, ungulates play an important role both in the ecosystem and in the economy. In general, species or breeds are considered endangered if their population does not exceed 1,000 individuals. In these cases conservation programmes should be initiated in order to maintain or even increase their number. This review deals with the possibilities and limitations of assisted reproductive technologies (ART) in the conservation of ecologically valuable wild, rare and indigenous ungulates. The methods discussed here are artificial insemination, cryopreservation of semen and embryos, embryo recovery and transfer, in vitro production of embryos, as well as micromanipulation techniques including sperm injection, assisted hatching and cloning. Some of these procedures are already being exploited in the breeding of farm ungulates, but more basic information about the reproductive patterns of wild, rare and indigenous animal species is needed before the routine use of ARTs.

Potential of assisted breeding techniques for the conservation of endangered mammalian species in captivity: a review

An alarming worldwide extinction of animal species is taking place as a result of the activities of the increasing global human population. The original ranges of many animal species are being reduced and fragmented and, in some cases, they have been reduced to perilously small relict populations. The adverse genetic consequences of these restrictions are becoming clear, as are possible methods for their alleviation. The concept of ex situ genetic management of small captive populations of endangered species with a view to re-introducing them into the wild is attracting increasing interest. Modern reproductive techniques will play an important role in such programmes, and it is likely that an increasing number of veterinarians will become involved. However, the literature describing the aims and methods of reproductive genetic management is scattered and often not readily available to interested veterinary surgeons. The aim of this review is to deal with this problem by describing some potential approaches to the captive breeding of endangered species.

Heterologous fertilization to characterize spermatozoa of the genus Bos

Advances in assisted reproductive techniques, specifically, development of protocols for production of in vitro matured, fertilized and cultured domestic bovine embryos, offer opportunities to apply these techniques to nondomestic bovidae in species preservation. Domestic bovine oocytes were inseminated with nondomestic bovine spermatozoa. Effects of heparin concentration, sperm concentration and their interaction on total and normal in vitro fertilization rates and on subsequent embryo development were evaluated. In different replications, semen from 3 Bos bison, 2 Bos gaurus, 1 Bos grunniens, and 1 Bos javanicus bulls was used. Treatment of spermatozoa included 2 heparin levels (2 and 8 micrograms/mL) and 3 sperm concentrations (1, 3 and 5 x 10(6)/mL). The B. grunniens bull exhibited excessive polyspermy in all treatments; therefore, 1 replicate was completed using 2 levels of heparin (0 and 1 microgram/mL) and 2 sperm concentrations (1 and 2 x 10(6)/mL). After 18 to 22 h, cumulus cells were removed from presumptive zygotes, and a portion thereof was compressed between a slide and coverslip and fixed in acetic acid:ethanol solution. Light microscopy was used to visualize pronuclei and the second polar body as a determinant of fertilization. Remaining presumptive zygotes were placed into embryo culture medium, and blastocyst development was assessed on Days 7 and 8 (fertilization = Day 0). Percentages of total and normal fertilization and of blastocyst formation were analyzed by a logistic regression model, isolating effects due to bull, heparin and sperm concentration, and to their interaction. Work presented here suggests that, just as in Bos taurus, the nondomestic bulls in the Bos species seem to have individual heparin and sperm concentration requirements for successful IVF. We conclude that each bull, domestic or nondomestic, needs to be evaluated individually. Preliminary sperm characterization using domestic cattle oocytes would result in a greater potential for generating purebred embryos of the desired species should scarce female gametes become available.