Semen characteristics of the adult male chimpanzee (Pan troglodytes)

The chimpanzee, because of its similarities to the human, is especially valuable in studies of reproductive function. However, relatively little is known about the physiology of reproduction in the adult male chimpanzee. This study provides, for five adult male chimpanzees, baseline values for testicular volume without and with pressure and for cellular and biochemical characteristics of ejaculates collected by artificial vagina (AV). There was no correlation between body weight and testicular volume measured without or with pressure. The ratios of mean testicular volume without and with pressure were not statistically different among animals. Statistical analysis of penetration of denuded hamster oocytes by ejaculated chimpanzee sperm revealed no correlations between sperm count and percentage of eggs penetrated. There was significant variability in concentrations of protein and fructose and in activities of alpha-glucosidase and acid phosphatase among samples from different animals. Computer-assisted motion analysis (CAMA) of sperm provided baseline data on motion parameters necessary for future evaluation of this technique for semen analysis in the chimpanzee. The level of demonstrated inter-animal variation mandates use of each animal as its own control for studies on normal and altered reproductive function. © 1993 Wiley-Liss, Inc.     

Immunohistochemical localization of epididymal secretory glycoprotein EP1 in the adult male chimpanzee.

Proteins, synthesized by the epididymal epithelium, are secreted sequentially into the lumen of the ducts epididymis where they effect sperm maturation and enable functional motility and fertilizing capacity. EP1 is a major secretory glycoprotein of chimpanzee (Pan troglodytes) epididymis. The epididymal duct exhibits diverse histology (Smithwick & Young, 1997). Epithelia I-V of the efferent ducts show no characteristic anti-EP1 binding. The densest granules of anti-EP1 reaction product appear in epithelium VI adjacent to the basal lamina in the infranuclear region of the principal cells (PCs), in the cytoplasm of the apical half of the PCs, and in the perinuclear and perivacuolar cytoplasm of the basal cells. In epithelia VII-XIV of the ductus epididymis proper, anti-EP1 binding decreases distally and is localized in the cytoplasm of the PCs and basal cells, among the stereocilia of the luminal border, within various microvillar borders, and in the luminal fluid. Therefore, EP1 appears to be synthesized and secreted primarily in the caput region of the ductus epididymis and may be reabsorbed nonselectively across epithelia with apical microvilli, including the non-ciliated cells of efferent ducts, the distal corpus and cauda of the ductus epididymis, and the proximal ductus deferens.     

Aggression in adult male primates: A comparison of confined Japanese macaques and free-ranging olive baboons

The frequencies and types of adult male aggressive behavior of confined Japanese macaques (Macaca fuscata)and free-ranging olive baboons (Papio anubis)were compared. The baboons, which do not have a mating season, were more aggressive to conspecific males than were the macaques during their nonmating season. The baboons also solicited aid during aggressive encounters more frequently than the macaques. However, during their mating season, the macaques were more aggressive to conspecific females than were the baboons. The macaques were also involved in more triadic sequences of aggression, and the frequency of occurrence of these patterns supported Chase’s theory of dominance hierarchy formation and maintenance. The differences in aggressive behavior appeared to be related to the seasonal reproductive cycle of the macaques.     

Group changing in free-ranging male rhesus monkeys

Group changing behavior of maleMacaca mulatta was studied over a six-year period at the rhesus monkey colony on two coastal islands at La Parguera, Puerto Rico. Males first left their natal group at a mean age of 47 months and became solitary for the first time at a mean age of 64 months; all had left their natal groups by seven years of age. Age, mating season, sex ratios of adult males and females in the social bands, and geographical barriers all had significant effects on the group shifting. Population size, rank of mother or being an orphan did not significantly affect the changing process. Two factors, age (size) and seniority in the group, were important in determining a male's rank in his new group.     

Comparison of instantaneous and locomotor bout sampling methods: a case study of adult male chimpanzee locomotor behavior and substrate use.

Currently two methods, instantaneous and locomotor bout sampling, are used most commonly in studies of locomotor behavior. To date, no study has addressed how comparable the results of the two methods are. This paper considers whether different sampling methods of locomotor behavior produce different results. Continuous locomotor bout and instantaneous sampling were carried out simultaneously on each focal animal during a seven month study of chimpanzee positional behavior in the Tai Forest of the Ivory Coast. Results provide two independent sets of data which describe the same events. Results indicate that as locomotor bouts are frequently presented (the percentage of bouts spent in an activity), they overrepresent the frequencies of activities that occur relatively often, but for short distances, and underrepresent activities that have a relatively large mean distance per bout. However, when bouts are weighted with distance, as originally defined by Fleagle (1976b), there are no significant differences in the results obtained by the two methods. Both provide similar results for the frequencies of locomotor activities, frequency of substrate use, and the relationship between substrate and locomotor activity. The advantage of instantaneous sampling is that because it is done at regular intervals, it can easily be carried out in conjunction with sampling other behavioral and ecological data. The advantages of locomotor bout sampling are that it permits the sampling of rare or brief locomotor events and allows for an analysis of sequences of locomotor activities. This paper demonstrates that the two methods can be conducted simultaneously and thus provide the richest return from which the effect of environment and morphology on locomotion can be addressed.     

Molecular thermal telemetry of free-ranging adult Drosophila melanogaster

The expression of two temperature-sensitive reporter genes, hsp70 and an hsp70-LacZ fusion, in free-ranging adult Drosophila melanogaster indicates that natural thermal stress experienced by such small and mobile insects may be either infrequent or not severe. Levels of the heat-shock protein Hsp70, the major inducible Hsp of Drosophila, were similar in most wild Droso- phila captured after warm days to levels previously reported for unstressed flies in the laboratory. In a transgenic strain transformed with an hsp70-LacZ fusion (i.e., the structural gene encoding bacterial β-galactosidase under control of a heat shock promoter), exposure to temperatures ≥32°C in the laboratory typically resulted in β-galactosidase activities exceeding 140 mOD₄₅₀ h^–1μg^–1 soluble protein. Flies caged in sun frequently had β-galactosidase activities in excess of this level, whereas flies caged in shade and flies released and recaptured on cool days did not. Most flies (>80%) released on warm, sunny days had low β-galactosidase activities upon recapture. Although the balance of recaptured flies had elevated β-galactosidase activities on these days, their β-galactosidase activities were <50% of levels for flies caged in direct sunlight or exposed to laboratory heat shock. These data suggest that even on warm days most flies may avoid thermal stress, presumably through microhabitat selection, but that a minority of adult D. melanogaster undergo mild thermal stress in nature. Both temperature-sensitive reporter genes, however, are limited in their ability to infer thermal stress and demonstrate its absence. Received: 14 July 1999 / Accepted: 21 December 1999     

Demographic and social constraints on male chimpanzee behaviour

Male chimpanzees, Pan troglodytes, are well known for affiliating and cooperating in a variety of behavioural contexts. Prior field research indicates that maternal kinship does not affect patterns of affiliation and cooperation by males in the same social group. Two questions remain unclear from this finding. First, why do male chimpanzees not bias their behaviour towards maternal kin? Second, what factors account for who affiliates and cooperates with whom? We conducted behavioural observations of an unusually large community of chimpanzees at Ngogo, Kibale National Park, Uganda, to test the hypothesis that demographic constraints limit the number of maternal kin with whom male chimpanzees can cooperate, and thereby lead them to form selective bonds with nonkin of similar age and status. Results indicated that male age and rank are significantly associated with four measures of social behaviour. Members of the same age class and individuals close in rank were more likely to affiliate and cooperate than males that belonged to different age and rank classes. Additional analyses replicate earlier findings and show that males who affiliated and cooperated were not closely related through the maternal line, as assayed by mtDNA haplotype sharing. These results add to our growing understanding of the important role demographic and social constraints play in animal behaviour.     

Interactions among adult males and females before and after the death of the alpha male in a free-ranging troop of Japanese macaques

This report documents the social interactions among adult Japanese macaques in a free-ranging troop before and after the death of the alpha male, who died at 28 years of age after occupying his rank position for 17 years. The alpha male’s physical condition had deteriorated due to his extreme age for several months before his death. However, he maintained his alpha position. When he was attacked by the second-ranking adult male, he was rescued by the alpha female. Thereafter, whenever the second-ranking male approached him, the alpha male screamed for the alpha female’s support. The number of adult females to whom the alpha male maintained proximity during his last four months was similar to that during the same period of the previous year. Prior to his death, the alpha male was observed in close proximity to the alpha female much more frequently than was the second-ranking male. These results indicate that the alpha male maintained his position by depending on female support and particularly that of the alpha female.     

Reproductive success of two male morphs in a free-ranging population of Bornean orangutans

The reproductive success of male primates is not always associated with dominance status. For example, even though male orangutans exhibit intra-sexual dimorphism and clear dominance relationships exist among males, previous studies have reported that both morphs are able to sire offspring. The present study aimed to compare the reproductive success of two male morphs, and to determine whether unflanged males sired offspring in a free-ranging population of Bornean orangutans, using 12 microsatellite loci to determine the paternity of eight infants. A single flanged male sired most of the offspring from parous females, and an unflanged male sired a firstborn. This is consistent with our observation that the dominant flanged male showed little interest in nulliparous females, whereas the unflanged males frequently mated with them. This suggests that the dominant flanged male monopolizes the fertilization of parous females and that unflanged males take advantage of any mating opportunities that arise in the absence of the flanged male, even though the conception probability of nulliparous females is relatively low.     

Socioecological factors of male chimpanzee migration at Bossou, Guinea

For more than 21 years a small semi-isolated group of wild chimpanzees have been studied at Bossou, Guinea, west Africa. All individuals have been identified since the beginning of the study. Remaining rates of infants (0–3 yr) and juveniles (4–7 yr) in the group were 64–80% for both sexes, however, those of adolescents (8–11 yr) dropped drastically, particularly for males (14%). As a result, most natal males as well as females disappeared before fully maturing. Two male visitors and an immigrant were observed in the group. More adult males than females disappeared from Bossou. Group males could be excluded as the genetic father of an offspring born in the group. From these demographic trends it is highly likely that some of these males emigrated rather than succumbed to sickness and death. It seems likely that they left on their own by choice. The reason for male dispersal is hypothesized to be influenced by intra-group male-male competition and the habitat ecology and structure of Bossou. There are no competitive adjacent groups or predators to prevent males from living alone and males can sire offspring out of their natal group.     

茶银尺蠖雄蛾触角的扫描电镜观察

本文采用扫描电镜对茶银尺蠖Scopula subpunctaria Herrich-Schaeffer雄蛾触角感受器进行了外部形态的观察和研究。结果表明,茶银尺蠖雄蛾的触角感受器主要有毛形感受器、鳞形感受器和刺形感受器3种。描述了各种感受器的形态特征和着生规律,对其主要生理功能进行了分析和讨论。     

A lone male chimpanzee in the wild: The survivor of a disintegrated unit-group

K Group, originally one of the two major study groups of chimpanzees since 1965 in the Mahale Mountains National Park, western Tanzania, was almost extinct by 1983: at most seven individuals remained in the group at the beginning of 1983. K Group continued to exist for more than four years, but in 1987 a male was left alone at the age of 15 after all the other chimpanzees of the group emigrated or disappeared. Since then he has been observed sporadically for more than five years only within the former range of K Group, without having any contact with the many resident chimpanzees of the neighboring M Group, the other major study group. The present observations reconfirm the strong philopatric tendency of adult male chimpanzees.     

Histological effects of androgen deprivation on the adult chimpanzee epididymis

Primate sperm acquire functional maturity, including vigorous forward motility and the ability to fertilize an ovum, as they transit the unique, regional microenvironment of the epididymal lumen. Several proteins secreted into this luminal fluid are epididymal-specific and androgen-dependent, and thus contribute potentially to sperm maturation. For the adult male chimpanzee, we report the effects of GnRH antagonist-induced androgen deprivation on the histology of the epithelia and interstitium composing the ductuli efferentes, ductus epididymis, proximal ductus (vas) deferens. After 21 days of androgen deprivation, epididymal tissues exhibit characteristic atrophic changes, including cellular disorganization, degradation, and loss of structures. Androgen-deprived cytoplasm is differentially and characteristically disrupted, vacuolated, and reduced in volume, resulting in decreased epithelial height and loss of stereocilia. Most principal cell nuclei appear hyperchromatic, smaller in size, more irregular in outline, and disordered in arrangement, while others appear swollen and vacuolated. Apical cells of the efferent ducts and the basal cells and microvillar borders of the ductus epididymis seem minimally affected by androgen deprivation. Such histologically differential responses suggest correspondingly that androgen is differentially essential to the maintenance of the epididymis and thus to normal functioning of the component tissues. Therefore, epididymal epithelia directly and their secretions indirectly are differentially androgen-dependent.     

Effects of androgen deprivation on the histology of adult chimpanzee testis

Until primate sperm are exposed to the unique microenvironment of the epididymis, they are not capable of fertilization or vigorous motility. Many of the proteins that contribute to the unique microenvironment of the primate epididymis, and thus to sperm maturation, are dependent on androgens to induce their synthesis and secretion. GnRH antagonists have proved effective in suppressing LH and testosterone synthesis and secretion, and thus in maintaining a state of androgen deprivation or functional hypogonadotropism. We report here the effects of GnRH antagonist-induced androgen-deprivation on the histology of the testicular interstitium and seminiferous epithelium of the adult male chimpanzee. After only 21 days of androgen-deprivation, chimpanzee testicular tissues exhibit specific atrophic changes, including the loss of contact between developing spermatocytes and between Sertoli cells and their developing spermatids, alterations in cell development resulting in missing maturation steps (elongating Sc and structurally complete Sd2 spermatids) and inappropriate cell associations, varying degrees of cytoplasmic degradation in germ cells, Sertoli cells, and Leydig cells, and a tubular lumen obscured by masses of sloughed primary and secondary spermatocytes and what appear histologically to be Sb1 and Sd1 spermatids.     

Effects of capture stress on free-ranging, reproductively active male Weddell seals

Physiological stress responses to capture may be an indicator of welfare challenges induced by animal handling. Simultaneously, blood chemistry changes induced by stress responses may confound experimental design by interacting with the biological parameters being measured. Cortisol elevation is a common indicator of stress responses in mammals and reproductive condition can profoundly influence endocrine response. We measured changes in blood cortisol and testosterone induced by handling reproductively active male Weddell seals (Leptonychotes weddellii) early and late in the breeding season. Weddell seals have the highest resting cortisol levels of all mammals yet showed a clear, prolonged elevation in cortisol in response to capture. Responses were similar when first caught and when caught a second time, later in the breeding season. Baseline testosterone levels declined over the breeding season but were not altered by capture. Administering a light dose of diazepam significantly ameliorated the cortisol response of handled animals without affecting testosterone levels. This may be an effective way of reducing acute capture stress responses. Male breeding success in years males were handled was no different to the years they were not, despite the acute capture response, suggesting no long-term impact of handling on male reproductive output.     

Spontaneous heart disease in the adult chimpanzee (Pan troglodytes)

Background  A high incidence of heart disease, especially idiopathic cardiomyopathy (IC), is seen in chimpanzees ( Pan troglodytes ).
Methods  We reviewed clinical records and necropsy reports of 87 adult chimpanzees for possible causes of heart disease/IC. We examined age, sex, cause of death, weight, diet, environment, infectious diseases, experimental uses and clinical pathology.
Results  The overall prevalence of heart disease in chimpanzees was 67.81%; the prevalence of IC was 51.72%. The prevalence of IC was significantly higher in males (60.32%) than that in females (29.17%, P  = 0.009). The prevalence of other heart disease was higher in females (25%) than that in males (12.70%, P  = 0.165). Heart failure occurred in 47.13% of chimpanzees. Heart disease was the primary cause of death in 34.49% of chimpanzees; 29.88% died of unknown causes.
Conclusions  We found no evidence that diet, environment, viral agents, experimental use or disease exposure contributed to the deaths resulting from IC in chimpanzees.