Collection and quality of rhesus monkey semen

Electroejaculation is an accepted method of semen collection from nonhuman primates. Although both penile and rectal probe stimulation techniques have been used, there has been a general lack of consistency and detail regarding their application. This report describes the collection, processing, and evaluation of rhesus monkey semen contrasting two methods of penile electroejaculation: 1) a constant-voltage method where stimulus current is a variable and 2) a constant-current method where stimulus current is operator-controlled. The constant-current method was the more efficient procedure, requiring a lower stimulus current for successful electroejaculation. The influence on semen quality of potentially toxic agents used in the procedure, surgical glove powder and electrolyte cream, was tested; both were detrimental as measured by motility loss. No correlation was found between coagula volume and sperm numbers. The intra- and interanimal variability in semen samples from six monkeys was also evaluated. Penile electroejaculation, combined with control of stimulus current, provides a consistent, successful, and humane method for the collection of semen in the rhesus monkey.     

Nitrogen distribution in several traditional agro-ecosystems in the humid tropical lowlands of south-eastern Mexico

Nitrogen distribution was examined in five local agro-ecosystems typical of the lowlands of tropical south-eastern Mexico: monoculture corn, corn/bean polyculture, manioc (yuca, cassava), taro (malanga), and upland rice. Total biomass and nitrogen content were determined monthly for standing live, standing dead, and litter biomass of both crop and non-crop components of each system. The crop component was further divided into roots, crown, stem, leaves, fruits, and flowers. Soil nitrogen determinations were also made monthly. Results demonstrated that nitrogen maintenance in the system is highly dependent on the proportion of the net biomass produced which is returned to the system. Leguminous and weed components may reduce net nitrogen losses from these systems.     

Chronic push-pull brain perfusion in unrestrained rhesus macaques

A system was developed to permit perfusion of local brain regions and simultaneous peripheral blood sampling in free-moving caged monkeys. The system comprises a calvarial headpiece that contains multiple push-pull cannulas (PPC), a flexible stainless steel tether, a four-channel fluid swivel, and a surgical procedure for simultaneous multisite brain cannulation. Rhesus macaques were fitted surgically with an indwelling jugular catheter and PPC directed into the third ventricle, median eminence, and preoptic area. These animals were tethered for periods of 14-70 h during which brain perfusates and peripheral blood samples were collected at 10- to 30-min intervals through the tether-swivel assembly. Levels and pulsatile patterns of gonadotropin-releasing hormone in 10-min perfusate samples and luteinizing hormone and cortisol in sequential plasma samples were quantified by specific radioimmunoassays. The normal endocrine profiles in these animals suggest that this system provides a valuable method to study patterns of neurosecretions in an unrestrained simian.     

Collection and fertilization potential of sperm from the Sulawesi crested black macaque (Macaca nigra)

In this study, semen was obtained by rectal probe electrostimulation (RPE) from the Sulawesi crested black macaque (Macaca nigra). Three experimental series were conducted. First, semen was collected from four animals anesthetized with either tiletamine-zolazepam (Telazol®) or ket-amine-HCl (Vetalar®) (five collections from each animal with each drug). Because of greater muscle relaxation and analgesia, we found tiletaminezolazepam to be an attractive alternative to ketamine-HCl as an anesthetic agent for RPE in M. nigra. Second, semen was collected from another four animals at stimulation frequencies of either 30 Hz or 60 Hz (five collections from each animal at each frequency). There were no significant differences in sperm number, in percentage of sperm with progressive motility, in the current required for sample recovery between tiletamine-zolazepam or ketamine-HCl anesthesia, or between a 30 Hz or 60 Hz stimulation frequency. Third, to check for retrograde sperm loss, the bladders of four animals were emptied, flushed with sterile saline, and then infused with TALP-Hepes medium. After RPE, sperm numbers in the bladder were compared with those in the ejaculate. Although sperm were recovered from the bladder [1.6 (± 0.9) × 10⁶] (mean ± SEM), the numbers were significantly less (P < 0.05) than those in the ejaculate [49 (± 18) × 10⁶]. The percentage of sperm with normal morphology in these samples was high (96.8 ± 1.0%). The average sperm number in the 84 samples collected for this study was 33.8 (± 4.1) × 10⁶. In preliminary experiments, we found that M. nigra sperm will fertilize rhesus monkey oocytes (Macaca mulatta) in vitro. © 1992 Wiley-Liss, Inc.