Vasoformative disorder, resembling littoral cell angioma, of the spleen in a geriatric Japanese macaque (Macaca fuscata).

A 30-year-old female Japanese macaque showed marked splenomegaly. The enlarged spleen consisted of neoplastic proliferation of anastomosing vascular channels resembling morphologic structures of red pulp sinuses; occasionally, papillary fronds were seen in dilated channels. Immunohistochemically, the lining cells reacted to both endothelial cell (von Willebrand factor) and macrophage (macrophage scavenger receptor class A) markers, indicating features of littoral cells of the spleen. Based on the pathologic characteristics, particularly the presence of neoplastic cells with macrophage/histiocyte-like attributes, this tumor was regarded as littoral cell angioma; this is a rare benign splenic vascular tumor.

Measurement of urinary and fecal steroid metabolites during the ovarian cycle in captive and wild Japanese macaques, Macaca fuscata.

We measured the concentration of steroid hormones from urine, feces, and blood samples of two captive Japanese macaques, Macaca fuscata, during nonconceptive ovarian cycles to compare the patterns of the excreted steroids with those of circulating steroids. Urine and feces were analyzed for estrone conjugates (E1C) and pregnanediol-3-glucronide (PdG) using enzyme immunoassays (EIAs), while plasma was analyzed for estradiol-17beta(E2), progesterone (P), and luteinizing hormone (LH) using radioimmunoassays (RIAs). Urinary and fecal E1C and PdG levels were approximately parallel to plasma E2 and P levels, respectively. The E1C profiles of daily urinary and fecal samples revealed a midcycle peak, followed by a sustained PdG increase lasting up to two weeks from the E1C peak. A fecal E1C peak was one day later than the urinary E1C peak. One of the captive females exhibited a discrete plasma LH peak, one indicator that ovulation has occurred, on the day following the urinary E1C peak, i.e., the same day of fecal E1C peak. We measured excreted steroids in nine wild females and determined the timing of ovulation by comparing fecal steroid profiles to those obtained in captive monkeys. Data from wild females indicated that eight of nine females conceived during their first ovulatory cycle of the sampling period, whereas the remaining female failed to conceive during the sampling period even though she ovulated. In the eight females that conceived, E1C increased again following the detected or estimated E1C peak, with levels comparable to the preovulatory peak levels, and sustained elevations of PdG for over 40 days. These data illustrate that the urinary and fecal profiles of ovarian steroid excretion obtained through the application of these noninvasive techniques provide an accurate approach for monitoring conceptive and nonconceptive ovarian cycle in captive and free-living Japanese macaques.

Development of full-length Trk B-immunoreactive structures in the prefrontal and visual cortices of the macaque monkey.

Distribution and morphological changes of cells containing the signal transducing neurotrophin receptor, full-length Trk B (fl-Trk B), were investigated in the prefrontal cortex (area FD) and the primary visual cortex (area OC) of the macaque monkey between embryonic day 140 and the adult stage. In area FD at the adult stage, fl-Trk B immunoreactivity was mainly observed in the pyramidal cells in layers II/III, V and VI. Small numbers of granule cells in layer IV were immunopositive. Bipolar and multipolar cells in layer II were rarely immunoreactive. At embryonic day 140, the number of fl-Trk B immunoreactive pyramidal cell was high, and gradually decreased until the adult stage. In layer IV, the number of fl-Trk B-ir cells was also high at embryonic day 140, and decreased remarkably from postnatal day 7 to the adult stage. On the other hand, in area OC at the adult stage, cells in layers II/III, IV, V and VI were fl-Trk B immunopositive. From embryonic day 140 until adulthood, the cells in layer IVc were fl-Trk B immunoreactive. The strongest fl-Trk B immunoreactivity in areas FD and OC occurred at postnatal month 6, coinciding with the time of the synapse overproduction. These findings suggest that ligands of fl-Trk B, such as BDNF and NT4/5 may be involved in the development and maintenance of the monkey cerebral cortices.

SINE-R.C2 (a Homo sapiens specific retroposon) is homologous to CDNA from postmortem brain in schizophrenia and to two loci in the Xq21.3/Yp block linked to handedness and psychosis.

We investigated the retroviral/retroposon hypothesis of schizophrenia by generating sequences with PCR primers based on a retroviral sequence recovered by Yee et al. [1998: Schizophr Res 29:92] from a cDNA library from postmortem brain tissue from an individual with psychosis in a genomic region (Xq21.3) that has been tentatively linked to schizophrenia and schizoaffective disorder by Laval et al. [1998: Am. J. Med. Genet. (Neuropsychiatr. Genet.) 81:420-427]. Within the block of homology with Yp that was generated by a transposition between the chimpanzee and Homo sapiens we find two sequences, HS307 and HS408, with a high degree of homology to but not identity with the schizophrenic brain cDNA. The closest match of these three sequences is to a family of retroposons, that has evolved from the HERV-K family of endogenous retroviruses, some members of which (e.g., SINE-R.C2) appear to be specific to the human genome. This element has been reported as a cause of Fukuyama-type muscular dystrophy [Kobayashi et al., 1998: Nature 394:388-392]. Such retroposons, as agents of change in the human genome, provide a strategy for investigating pathogenesis. On account of their genomic location in a region that has been subject to change in the course of hominid evolution, and that may have a relationship to psychosis and/or cerebral asymmetry, we conclude that these particular insertions deserve further investigation.

Development of full-length Trk B-immunoreactive structures in the hippocampal formation of the macaque monkey.

Distribution and morphological changes of cells containing the signal transducing neurotrophin receptor, full-length Trk B (fl-Trk B), were investigated in the hippocampal formation of the macaque monkey between embryonic day 140 and the adult stage. Western blot analysis showed that one main protein band, which migrated at 141 kDa, was detected in both the embryonic and adult hippocampal formation. In the pyramidal cells in CA1 and CA3 subfields, the subiculum, and the entorhinal cortex, fl-Trk B-immunoreactive dendrites were observable in the embryonic stage. In contrast, in the granule cells of the dentate gyrus, few dendrites were immunoreactive during embryonic and early developmental stages. This difference may be due to the later growth of the granule cells of the dentate gyrus. The existence of fl-Trk B immunoreactivity in the cell body and dendrites in the embryonic hippocampal neurons, suggests that BDNF and/or NT4/5 act on the hippocampal cells by autocrine/paracrine mechanisms. In the entorhinal cortex, fl-Trk B immunoreactivity became localized in the stellate cells in layer II and the pyramidal cells in layers III, V and VI in adulthood. This indicates that BDNF and/or NT4/5 are important for the maintenance of the projection neurons in the entorhinal cortex at the adult stage. The strongest fl-Trk B immunoreactivity in the hippocampal neurons occurred at postnatal month 4, corresponding to the period of greatest synapse production in the monkey hippocampus, suggesting that BDNF and/or NT4/5 with fl-Trk B may play a role in synapse formation in the monkey hippocampus.

Female mating strategy in an enclosed group of Japanese macaques.

Female Japanese macaques (Macaca fuscata) are noted for mating with multiple males and for their ability to exert mate choice. In a captive group of Japanese macaques housed at the Primate Research Institute of Kyoto University, Japan, behavioral and endocrine data were combined to examine female mating strategies. During one breeding season, daily behavioral observations were conducted on females who exhibited copulatory behavior. Blood was collected from females twice weekly and their ovulatory periods estimated by analyzing hormone profiles. Females began mating shortly before ovulation, peaked at ovulation, and continued receiving ejaculations for up to ten weeks after conception. Females were more responsible than males for inbreeding avoidance with matrilineal kin. Males sometimes approached females from their own matriline, but females avoided such males and expressed mate choice behavior preferentially toward non-matrilineal males. Over the entire mating season, females did not choose non-matrilineal males on the basis of displays, dominance rank, age, weight, or weight change during the mating season. When females were likely to conceive, however, they expressed mate choice behavior toward males who displayed most frequently. Female mating strategy may include both mate choice at ovulation and other, non-procreative functions.

Sexual selection in Japanese macaques I: female mate choice or male sexual coercion?

Mate choice is defined as a behavioural pattern in one sex which increases the probability of fertile matings with certain members of the opposite sex. The chosen sex may use force, however, to coerce matings from reluctant members of the choosing sex. In a confined group of Japanese macaques, Macaca fuscata fuscatahoused at the Primate Research Institute of Kyoto University, Japan, behavioural and endocrine data were combined to assess the validity of several mate-choice behaviours and the potential influence of sexual coercion. Preliminary evidence was found for both female mate choice of males and male sexual coercion of females. Both female proximity maintenance towards males and male aggression towards females were correlated with an increase in fertile matings. Most male aggression appeared to be the by-product of increased time spent in proximity due to female proximity maintenance, but some male aggression appeared to be sexual coercion. These results are interpreted in light of recent research on male sexual coercion, and a tentative model of mate choice for this species is proposed.1997The Association for the Study of Animal Behaviour

Sexual selection in Japanese macaques II: female mate choice and male-male competition

Mating and reproductive outcomes are the product of the potentially conficting strategies of breeding males and females. In a captive group of Japanese macaques, Macaca fuscata fuscatabehavioural, endocrine and genetic data were combined to assess the independent effects of male-male competition and female mate choice on mating and reproductive success. Males were ranked by social dominance and by their attractivity to females. Computer simulation and logistic regression analyses showed that male attractivity had a stronger effect than male dominance on both mating and reproductive outcome. Although male dominance and attractivity both significantly predicted mating success during fertile periods, only male attractivity significantly predicted actual male reproductive success. These results provide evidence that female mate choice can be a stronger determinant of mating and reproductive outcome in this species when male and female strategies are in conflict. The lack of a consistent correlation between male dominance rank and reproductive success in this species may be accounted for in part by female mate choice of socially subordinate males. Sires who were observed to mate with the mother during her fertile period were more likely to be socially dominant than sires who were not observed to do so. This observation suggests the existence of alternative mating strategies by subordinate males, which may also contribute to the lack of a consistent correlation between male dominance rank and reproductive success in this species.1997The Association for the Study of Animal Behaviour

Reproductive senescence in female Japanese monkeys (Macaca fuscata): age- and season-related changes in hypothalamic-pituitary-ovarian functions and fecundity rates.

Age- and season-related changes in gonadotropin-gonadal functions were studied in captive female Japanese monkeys (Macaca fuscata fuscata), with special reference to reproductive senescence. In experiment 1, a total of 57 nonlactating females at ages 3-32 yr were used. Blood samples were collected for at least one breeding season (September through March), and changes in plasma concentrations of LH, estradiol, and progesterone were examined. In experiment 2, two groups of females (older females, n = 5, over 21 yr old; mature females, n = 5, aged 8-12 yr) received s.c. injections of 50 micrograms/kg of estradiol benzoate during the mid-breeding season. In experiment 1, ovarian functions as well as fecundity rates were maintained in the animals aged 5-20 yr. A decline in ovarian activity became apparent at 21-25 yr of age, when animals exhibited a slight increase in plasma LH during the breeding season. Onset of menopause occurred at around 27 yr of age, near the end of the life span. Menopausal females exhibited a marked seasonal difference in plasma LH concentrations, with high levels during the breeding season. In experiment 2, estradiol treatment elicited an LH surge in both old and mature females. The marked seasonal difference in plasma LH, as well as the maintenance of LH response to estradiol in menopausal females, suggests a possibility that biannual changes in sensitivity of the hypothalamo-hypophysial axis to the negative feedback action of estradiol are maintained even after menopause.