Reproductive one health in primates

One Health is a collaborative trans-disciplinary approach to health; integrating human, animal, and environmental health. The focus is often on infection disease transmission and disease risk mitigation. However, One Health also includes the multidisciplinary and comparative approach to disease investigation and health of humans, animals, and the environment. One key aspect of environmental/ecosystem health is conservation, the maintenance of healthy, actively reproducing wildlife populations. Reproduction and reproductive health are an integral part of the One Health approach: the comparative aspects of reproduction can inform conservation policies or breeding strategies (in situ and ex situ) in addition to physiology and disease. Differences in reproductive strategies affect the impact poaching and habitat disruption might have on a given population, as well as ex situ breeding programs and the management of zoo and sanctuary populations. Much is known about chimpanzees, macaques, and marmosets as these are common animal models, but there is much that remains unknown regarding reproduction in many other primates. Examining the similarities and differences between and within taxonomic groups allows reasonable extrapolation for decision-making when there are knowledge gaps. For example: (1) knowing that a species has very low reproductive rates adds urgency to conservation policy for that region or species; (2) identifying species with short or absent lactation anestrus allows ex situ institutions to better plan contraception options for specific individuals or prepare for the immediate next pregnancy; (3) recognizing that progestin contraceptives are effective contraceptives, but may be associated with endometrial hyperplasia in some species (in Lemuridae but not great apes) better guides empirical contraceptive choice; (4) recognizing the variable endometriosis prevalence across taxa improves preventive medicine programs. A summary of anatomical variation, endocrinology, contraception, pathology, and diagnostics is provided to illustrate these features and aid in routine physical and postmortem examinations as well as primate management.

Gynaecological diagnosis by ultrasound and the measurement of urinary sex steroid hormones in female orangutans

Gynaecological diagnoses were carried in three adult female orangutans (Pongo spp.) using ultrasound, and their estrous states were estimated by measuring urinary sex steroid hormone concentrations using enzyme immunoassay. Ultrasound diagnosis revealed that the endometrial thickness and follicle size were correlated with the oestrogen‐3‐glucuronide concentrations in the follicular phase. In addition, administration of the ovulation inducer human chorionic gonadotropin (hCG) had the strongest effect on the pregnanediol‐3‐glucuronide (PdG) concentration when the follicle size was 22.3 mm, suggesting that the follicle reaches this size before ovulation. The similarity between this and the maximum ovarian follicle size in humans (approximately 20 mm) indicates that the ancestral reproductive characteristics may have been retained in these species.

Medical and surgical management of reproductive neoplasia in two western lowland gorillas (Gorilla gorilla gorilla)

BACKGROUND

Reports of female reproductive tract neoplasia are infrequent in great apes.

METHODS

Two captive-born, female western lowland gorillas (Gorilla gorilla gorilla) housed at the North Carolina Zoological Park were diagnosed with reproductive neoplasia.

RESULTS

The first gorilla had uterine endometrial thickening and uterine fibroids diagnosed during a routine annual examination. Subsequently, the animal underwent several uterine curettage procedures in an attempt to debulk the uterine mass. Biopsy results indicated uterine adenocarcinoma. The animal was treated with an ovariohysterectomy followed by a combination of megestrol acetate and medroxyprogesterone acetate. The second gorilla was diagnosed with squamous cell carcinoma of the vagina, cervix, and uterus after presenting for intermittent vaginal bleeding of 1-month duration. This animal underwent palliative radiation therapy, receiving two rounds of radiation treatment 8 weeks apart.

CONCLUSIONS

The following report describes the diagnosis and management of the two cases.

Flow Cytometric Sorting of Fresh and Frozen-Thawed Spermatozoa in the Western Lowland Gorilla (Gorilla gorilla gorilla)

We adapted flow cytometry technology for high-purity sorting of X chromosome-bearing spermatozoa in the western lowland gorilla (Gorilla gorilla gorilla). Our objectives were to develop methodologies for liquid storage of semen prior to sorting, sorting of liquid-stored and frozen-thawed spermatozoa, and assessment of sorting accuracy. In study 1, the in vitro sperm characteristics of gorilla ejaculates from one male were unchanged (P > 0.05) after 8 hr of liquid storage at 15 degrees C in a non-egg yolk diluent (HEPES-buffered modified Tyrode's medium). In study 2, we examined the efficacy of sorting fresh and frozen-thawed spermatozoa using human spermatozoa as a model for gorilla spermatozoa. Ejaculates from one male were split into fresh and frozen aliquots. X-enriched samples derived from both fresh and frozen-thawed human semen were of high purity, as determined by fluorescence in situ hybridization (FISH; 90.7%+/-2.3%, overall), and contained a high proportion of morphologically normal spermatozoa (86.0%+/-1.0%, overall). In study 3, we processed liquid-stored semen from two gorillas for sorting using a modification of methods for human spermatozoa. The sort rate for enrichment of X-bearing spermatozoa was 7.3+/-2.5 spermatozoa per second. The X-enriched samples were of high purity (single-sperm PCR: 83.7%) and normal morphology (79.0%+/-3.9%). In study 4 we examined frozen-thawed gorilla semen, and the sort rate (8.3+/-2.9 X-bearing sperm/sec), purity (89.7%), and normal morphology (81.4%+/-3.4%) were comparable to those of liquid-stored semen. Depending on the male and the type of sample used (fresh or frozen-thawed), 0.8-2.2% of gorilla spermatozoa in the processed ejaculate were present in the X-enriched sample. These results demonstrate that fresh or frozen-thawed gorilla spermatozoa can be flow cytometrically sorted into samples enriched for X-bearing spermatozoa.

Birth of a western lowland gorilla (Gorilla gorilla gorilla) following in vitro fertilization and embryo transfer

A 21-year-old multiparous female exhibiting 31-41 day menstrual cycles was given hFSH (225 IU/day, Metrodin 75, from cycle day 3 through 9 (menses = day 1) and hCG (10,000 IU, Profasi, on day 10 to stimulate follicular development. At 35 h after hCG, under isoflurane (AErrane) anesthesia, follicles were aspirated by controlled suction under transvaginal ultrasound guidance. Metaphase II oocytes (n = 11) were placed in modified human tubal fluid (mHTF, 100 microliters) medium under oil at 37 degrees C in humidified 5% CO2. Frozen semen, collected by voluntary ejaculation, was thawed (70 degrees C H2O bath, 6 sec), diluted slowly, centrifuged, and resuspended in mHTF, and 160,000 motile spermatozoa/ml were added at 6 h after oocyte recovery. At 21 h postinsemination (p.i.) eight oocytes were at the two-cell stage, five were cryopreserved, and three were cultured to the six- to eight-cell stage in mHTF with granulosa cells before transcervical uterine transfer at 47 h p.i. using a Teflon catheter. Micronized progesterone (400 mg/d) was orally administered for 10 weeks posttransfer (p.t.). Ultrasound examination revealed a single fetus at 15 weeks p.t., and unassisted delivery of a live 1.37 kg female infant occurred at 29 weeks. Am. J. Primatol. 41:247-260, 1997.

In vitro manipulation of nonhuman primate gametes for embryo production and embryo transfer

Since nonhuman primates are closely related to humans and share many physical similarities, they are important for use in research areas such as human infectious diseases, reproduction, physiology, endocrinology, metabolism, neurology and longevity. To develop and maintain these animals, we must establish techniques for in vitro manipulation of spermatozoa and eggs. For a decade my research group has been conducting basic research to establish embryo manipulation techniques and to clarify the reproductive phenomena in nonhuman primates. This article summarizes the past research on in vitro manipulation of nonhuman primate gametes, from collection of reproductive cells and in vitro fertilization to the birth of offspring after embryo transfer, as well as the current status of these research areas. The studies summarized here will directly lead to the development of standard techniques for practical and comprehensive use in nonhuman primates.

Strategies for ovulation induction and oocyte retrieval in the lowland gorilla

PURPOSE

Ovulation induction and oocyte retrieval were performed in a lowland gorilla in an attempt to propagate and potentially cryopreserve embryos from an infertile animal and to advance techniques to help preserve this endangered species.

RESULTS

Following 34 days of leuprolide acetate suppression, human menopausal gonadotropins were administered for 14-days in a 32-year-old wild-born lowland gorilla. Ten oocytes were retrieved by transrectal ultrasound-guided aspiration. Other approaches to oocyte recovery were not feasible in this case. A serum estradiol concentration of 4700 pg/ml at the time of human chorionic gonadotropin administration did not induce ovarian hyperstimulation. Mature oocytes were recovered from follicles measuring 14 to 24 mm in diameter, with a corresponding average serum estradiol concentration of approximately 300 pg/ml for each mature follicle. Cryopreservation of a gorilla embryo was effected from cryopreserved gorilla spermatozoa.

CONCLUSIONS

Parameters for monitoring ovulation induction in the gorilla appear to be similar to those for humans. The results indicate that the use of a gonadotropin releasing hormone agonist and higher doses of gonadotropins than previously used in gorillas appear to improve oocyte recovery.

In vitro fertilization and gamete micromanipulation in the lowland gorilla

PURPOSE

Our purpose was to utilize current reproductive technologies to treat an infertile female lowland gorilla.

RESULTS

Following pituitary down-regulation with a gonadotropin releasing hormone agonist and follicular stimulation with human menopausal gonadotropins, transrectal ultrasound-guided aspiration of ovarian follicles yielded nine oocytes. Following failed fertilization with both epididymal and electroejaculated sperm, zona dissection and sperm injection were performed and produced one embryo, which was cryopreserved. Immature oocytes were obtained from ovarian sections and were either cultured in vitro or cryopreserved.

CONCLUSIONS

This report demonstrates that in vitro fertilization techniques, including pituitary suppression, ultrasound-guided aspiration, micromanipulation, and cryopreservation, can be used to assist reproduction in the lowland gorilla.

Penetration of zona-free hamster oocytes by ejaculated cryopreserved gorilla spermatozoa

Semen obtained by electroejaculation from two lowland gorillas were cryopreserved in TEST yolk to evaluate the ability of spermatozoa to penetrate zona-free hamster oocytes. Thawed semen was processed through a two-layer Percoll density gradient to obtain motile spermatozoa for the SPA. The processed sperm penetrated greater than 25% of the zona-free hamster oocytes. Thus, the use of TEST yolk to cryopreserve gorilla semen and processing the thawed semen through Percoll gradient to concentrate motile spermatozoa may facilitate sperm capacitation and the ability to penetrate oocytes.