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PubMed1990

Extension of reproductive suppression by pheromonal cues in subordinate female marmoset monkeys, Callithrix jacchus.

Pheromonal signals from the dominant female marmoset monkey were implicated in maintaining the suppression of LH secretion and ovulation in socially subordinate females. When subordinate, and reproductively suppressed, female marmoset monkeys were removed from their group without scent contact with their dominant females, subordinate females in control group 1 (N = 8) and control group 2 (N = 5), ovulated 10.8 +/- 1.4 days and 10.4 +/- 0.8 days respectively (mean +/- s.e.m.) after separation. Subordinate females (N = 8) removed from their dominant female and group, but maintained in scent contact only with their dominant females, showed a delay in the onset of ovulation (31.0 +/- 6.4 days) compared with control groups 1 and 2. Plasma LH concentrations of subordinate females during the scent transfer phase were lower than in controls without scent transfer and comparable to those seen whilst the females were subordinates in groups. Contact of subordinate females with olfactory stimuli from dominant females therefore maintains the suppression of both LH secretion and ovulation in socially subordinate female marmosets. Such pheromonal cues provide evidence of a quantifiable link between dominant female marmosets and the maintenance of physiological suppression of reproduction in their female subordinates.

Animals↗
PubMed1992

Stimulation of immunoreactive inhibin production by preimplantation embryos during early pregnancy in the marmoset monkey (Callithrix jacchus).

The role of the embryo in promoting increased plasma concentrations of immunoreactive inhibin after conception in the marmoset monkey was determined by flushing embryos from the uterus between days 5 and 9 after ovulation (implantation commences on days 11-12). Blood samples were taken from each animal (three times a week) after ovulation until the end of the luteal phase. Plasma inhibin concentrations were measured using a radioimmunoassay based on antisera against a synthetic fragment of the alpha-subunit of human inhibin. When embryos were flushed on days 5 and 6 (n = 6) after ovulation inhibin concentrations did not exceed 250 ng ml-1 for the duration of the luteal phase. In contrast when embryos were flushed on days 7 (n = 4), 8 (n = 4) and 9 (n = 3) maximum concentrations of inhibin always exceeded 250 ng ml-1, reaching > 400 ng ml-1 when embryos were flushed on days 8 and 9. Inhibin concentrations remained high for the duration of the luteal phase, which varied in length between 20 and 32 days. Significantly (P < 0.01) higher mean plasma concentrations of immunoreactive inhibin were first recorded on days 7-8 after ovulation in animals that had embryos flushed on days 7, 8 and 9 compared with concentrations in animals that had embryos flushed on days 5 and 6. Inhibin could not be detected in the medium of embryos cultured for up to 2 weeks.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

Sensory cues and the suppression of reproduction in subordinate female marmoset monkeys, Callithrix jacchus.

Subordinate female marmoset monkeys remain anovulatory and have low plasma concentrations of luteinizing hormone (LH) when maintained with their dominant females. Olfactory cues from the dominant female have been implicated in maintaining this reproductive suppression. Subordinate females that received either ablation of the vomeronasal organ (an accessory olfactory organ; n = 3), ablation of the main olfactory epithelium (n = 4), or both lesions (n = 5) did not ovulate in the following 7 weeks while housed with their dominant female. Plasma LH concentrations following either or both lesions were similar to pre-lesion concentrations. Olfactory lesions (verified by histological and behavioural trials) did not impair reproductive activity, as olfactory-lesioned dominant females underwent ovarian cycles of similar duration to intact dominant females. Lesioned subordinate females (n = 6), maintained in visual-only contact with their dominant female and group ovulated 29.1 +/- 9.3 days (mean +/- SEM) after physical separation from their dominant females; this first onset of ovulation was significantly delayed (P < 0.05) compared with intact subordinate females completely isolated from their dominant females and group (10.8 +/- 1.3 days, n = 8). Behavioural and visual cues together with olfaction all appear to play important roles in maintaining the suppression of ovulation in subordinate female marmoset monkeys.

Animals↗
PubMed1993

Requirement of inner cell mass for efficient chorionic gonadotrophin secretion by blastocysts of common marmosets (Callithrix jacchus).

The role of the inner cell mass in the induction of chorionic gonadotrophin synthesis and secretion by the trophoblast of the peri-implantation primate blastocyst was studied in common marmoset monkeys. An in vitro system for the culture of blastocysts commencing with blastocysts collected 8 days after conception was developed. Chorionic gonadotrophin measured in the spent culture fluid was first detected in most blastocysts after 3 or 4 days (day 11 or 12) of culture at a time equivalent to implantation in vitro. Initial secretion of chorionic gonadotrophin coincided with development of parietal endoderm and histological appearance of syncytiotrophoblast in the polar trophoblast. Little chorionic gonadotrophin was secreted by blastocysts with a poorly developed, or absent, inner cell mass. Mural trophoblast removed from blastocysts after 2 days of culture (day 10) grew in vitro as a unilaminar vesicle but failed to secrete significant amounts of chorionic gonadotrophin. However, mural trophoblast from older blastocysts (days 13 and 14) after chorionic gonadotrophin secretion had commenced continued to secrete chorionic gonadotrophin, with trophoblast from day 14 blastocysts secreting significantly more than that from day 13. It was concluded from these studies that while mural trophoblast from marmoset blastocysts will proliferate in vitro in the absence of an inner cell mass, efficient induction of chorionic gonadotrophin secretion requires the presence of the inner cell mass or its derivatives. Once chorionic gonadotrophin secretion has commenced, secretion will continue in the absence of the inner cell mass.

Animals↗
PubMed1993

Roles of cyclic AMP and inositol phosphates in the luteolytic action of cloprostenol, a prostaglandin F2 alpha analogue, in marmoset monkeys (Callithrix jacchus).

The luteolytic response to a prostaglandin F2 alpha analogue, cloprostenol, was investigated in vivo and in vitro at defined stages of the luteal phase. In vivo administration of cloprostenol to female marmoset monkeys on day 3 after ovulation had no effect on plasma progesterone concentrations, whereas administration on day 14 after ovulation reduced plasma progesterone to preovulatory concentrations within 4 h. To identify the cellular basis for this luteolytic action, marmoset luteal tissue obtained on days 3, 6 and 14 after ovulation was incubated in vitro and progesterone production, cAMP accumulation and phosphoinositide (PI) turnover measured in response to cloprostenol, human chorionic gonadotrophin (hCG) with or without cloprostenol, or dibutyryl-cAMP with or without cloprostenol. Progesterone production was stimulated by both hCG and dbcAMP at all stages of the luteal phase. Although neither hCG nor dbcAMP had any significant effects on PI turnover, hCG also increased cAMP accumulation. In marmoset luteal tissue obtained on day 3 after ovulation, cloprostenol had no significant effect on basal or hCG/dbcAMP-stimulated progesterone production but significantly stimulated PI turnover. In contrast, on days 6 and 14 after ovulation, cloprostenol significantly inhibited hCG- and dbcAMP-stimulated progesterone production and the cAMP response to hCG, but had no significant effect on PI turnover. Since progesterone production by the marmoset corpus luteum depends on the luteotrophic support of luteinizing hormone (LH), these observations suggest that the luteolytic action of cloprostenol in vivo involves the inhibition of LH/hCG action at sites both prior and subsequent to cAMP accumulation. However, such luteolytic effects do not appear to require the generation of inositol phosphates by increased PI turnover.

Animals↗
PubMed1993

In vitro fertilization and embryo development in the marmoset monkey (Callithrix jacchus).

Oocytes aspirated from preovulatory (i.e. > or = 2 mm) follicles of marmoset monkeys were graded for maturity according to the degree of cumulus expansion, grade I being most mature and grade IV least mature. After preincubation for 2-5, 9-11 or 21-29 h, 82% of oocytes could be fertilized using epididymal spermatozoa and only 2.3% were polyspermic. Fertilization rate was lowest (60%) in grade IV oocytes and all oocytes preincubated for 2-5 h (53%). Fertilization rate increased to 92% in oocytes preincubated for 21-29 h. Embryos developed in vitro to a mean of eight cells. Embryo development was unaffected by oocyte maturity but correlated with preincubation time. Oocytes preincubated for 2-5 h developed into embryos with significantly fewer cells than those preincubated for 9-11 or 21-29 h (P < 0.001). Fifty-six per cent of embryos showed delayed cleavage and these had fewer cells than non-delayed embryos (P < 0.001). When oocytes were preincubated for 2-5 h, development of all resulting embryos was delayed. However, only 17 and 58% of embryos developing from oocytes preincubated for 9-11 and 21-29 h, respectively, were delayed and this was independent of oocyte maturity.

Animals↗
PubMed1997

Cell death during luteal regression in the marmoset monkey (Callithrix jacchus).

The mechanism controlling luteal regression in primates is unknown but may involve cell death by apoptosis. Marmoset ovaries containing corpora lutea were studied at different stages of the normal ovarian cycle. Two additional groups of animals underwent induced luteolysis with either the prostaglandin F2 alpha analogue, cloprostenol, or the GnRH antagonist, antarelix, at the mid-luteal phase. Apoptosis in ovarian sections was estimated both by counting the number of cells exhibiting morphological features of apoptosis and by in situ labelling the 3' ends of the DNA fragments with digoxigenin-11-dUTP. Apoptosis was found to be significantly increased in corpora lutea in the early follicular phase (equivalent to the later stage of luteal lifespan) compared with the mid-luteal phase corpora lutea, as judged by either computerized morphometry or 3' end labelling. Apoptosis was also increased by the administration of either cloprostenol or antarelix when using the 3' end labelling end point, but only after cloprostenol when using computerized morphometry. A further form of cell death, characterized by the formation of cytoplasmic vacuoles, was also observed in corpora lutea undergoing both induced and spontaneous regression. These results demonstrate that apoptosis within the primate corpus luteum is increased in both physiological and induced luteal regression. In addition, they show that an alternative form of cell death is involved in both spontaneous and induced luteal regression, although the relative importance of the two mechanisms remains to be determined.

Animals↗
PubMed1998

Ubiquitin and apoptosis in the corpus luteum of the marmoset monkey (Callithrix jacchus).

The polypeptide ubiquitin covalently binds to cytoplasmic proteins and marks them for proteolytic degradation. Ubiquitin is upregulated during apoptosis in some systems. Apoptosis increases during luteolysis but it is not known whether ubiquitin is expressed in regressing corpora lutea. Marmoset ovaries were removed on day 10 of the luteal phase from animals that had received either no treatment, treatment with the PGF2 alpha analogue cloprostenol 24 h earlier, or treatment with the GnRH antagonist antarelix for either 24 or 48 h before ovary collection. Ubiquitin was localized on ovarian sections by immunocytochemistry, and oligonucleosome formation characteristic of apoptosis was examined in isolated corpora lutea by electrophoresis of extracted [32P]DNA. Oligonucleosome formation was low in midluteal corpora lutea on day 10 but increased after induced luteal regression with PGF2 alpha and GnRH antagonist. Nuclear ubiquitin immunoreactivity was found in 1.66 +/- 0.66 steroidogenic cells and cytoplasmic staining was found in 0.4 +/- 0.3 steroidogenic cells (per x 40 field of view) in midluteal phase corpora lutea on day 10. Luteolytic induction with PGF2 alpha significantly increased the number of cells exhibiting cytoplasmic immunoreactivity to 12.24 +/- 1.6 (P < 0.05). Ubiquitin immunoreactivity was not observed after GnRH-induced luteal regression. Apoptotic oligonucleosome formation was found after induced luteal regression with both PGF2 alpha and GnRH antagonist, but ubiquitin upregulation only occurred after PGF2 alpha-induced regression. These results indicate that ubiquitin expression is not specific for luteolysis and is not an indicator of luteal apoptosis, but that the polypeptide does play a role in luteal cellular responses to PGF2 alpha.

Animals↗
PubMed2003

Localization of mRNA for vascular endothelial growth factor (VEGF), angiopoietins and their receptors during the peri-implantation period and early pregnancy in marmosets (Callithrix jacchus).

Implantation of a blastocyst into a receptive endometrium is a prerequisite for successful pregnancy. Angiogenesis is a key event in this process but the mechanisms by which localized changes in vascular permeability and angiogenesis occur have yet to be elucidated. Vascular endothelial growth factor (VEGF) and its receptors VEGFR-1 and VEGFR-2 have been implicated as key players in vascular remodelling and placentation. Angiopoietins also appear to have a significant role in regulation of blood vessel growth, maturation and regression. The aim of this study was to describe the molecular regulation of angiogenesis in the first month of pregnancy in marmosets and to address the putative physiological roles for these factors. Uteri were studied at weeks 2, 3 and 4 of pregnancy and compared with late secretory non-pregnant endometrium. Implantation in marmosets occurs at day 11 of pregnancy; hence, these time points were chosen so that the peri-implantation period and very early pregnancy could be studied. mRNAs for VEGF, VEGFR-1 and VEGFR-2, angiopoietin 1, angiopoietin 2 and their receptor Tie-2 were localized and quantified by in situ hybridization. Endothelial cells were identified by CD31 immunocytochemistry. VEGF mRNA was present in all compartments except endothelial cells, and its expression generally increased throughout pregnancy except in upper zone glandular epithelium and luminal epithelium, where a decrease in expression was observed. VEGF receptor mRNAs were found in endothelial cells of the upper zones immediately surrounding glandular epithelium. Angiopoietin 1 mRNA was localized to glandular epithelium of the upper and lower zones throughout pregnancy, and increased in stroma at week 4. Expression of angiopoietin 2 mRNA was localized exclusively to endothelial cells of large luminal vessels and was higher in endometrium from marmosets at week 4 of pregnancy than in endometrium from all other stages. These data provide comprehensive evidence that VEGFR-1 and -2, and angiopoietin 1, angiopoietin 2 and Tie-2 interactions may be involved in the preparation of endometrium for implantation, remodelling of the maternal vasculature and trophoblast invasion during the peri-implantation period in this primate species.

Angiogenesis Inducing Agents↗
PubMed2004

Angiogenesis and microvascular development in the marmoset (Callithrix jacchus) endometrium during early pregnancy.

The aim of the study was to describe and quantify the changes in the maternal vasculature and angiogenesis during early pregnancy in the marmoset endometrium using bromodeoxyuridine (BrdU) to identify proliferating cells, CD31 to label endothelial cells and dual staining to identify proliferating endothelial cells. Non-pregnant animals from mid- and late secretory stages were studied and compared with pregnant animals at weeks 2, 3 and 4 of pregnancy. Qualitative and morphometric analyses of angiogenesis and vascular area were performed. The results show that pregnancy is associated with increasing angiogenesis in the upper zone of the endometrium, becoming significantly increased at 3 weeks. This is associated with an increase in the vessel area and diameter in this zone. These results provide the platform from which to design studies in which specific angiogenic factors can be targeted in vivo during early pregnancy in order to determine their role in regulating these vascular changes.

Animals↗
PubMed2006

Changes in endocrine profile and reproductive organs during puberty in the male marmoset monkey (Callithrix jacchus).

Data on pubertal maturation in male marmoset, a model for human reproduction, are scant and conflicting. We collected data on novel parameters to characterize puberty. Twenty-five marmoset monkeys were assigned to five age groups by weeks (wk): 21 (pre-pubertal), 43 (onset of puberty), 52 (fully pubertal), 70 (mature), and 116 (fully adult). Serum and intratesticular testosterone and pituitary bioactive chorionic gonadotropin (bioCG) were measured. Testicular development was assessed by ultrasonography, histology, and flow cytometry. Three consecutive blood samples revealed extreme fluctuations in testosterone concentrations, suggesting an erratic secretion. Age-related changes in serum testosterone and pituitary bioCG concentrations were observed. Intratesticular androgens (ITAs) showed high fluctuations within groups at all ages and were high in some animals by 21 wk. Unexpectedly, no correlation between pituitary bioCG and serum testosterone or ITAs was found, but these parameters significantly correlated with testicular weight and volume. These observations were consistent a dependence on the testis growth on bioCG. Unfortunately, the low serum levels of bioCG were not measurable in this study. At 43 wk, the animals reached puberty. At 52 wk of age, animals attained maximum body and epididymal weights and qualitatively normal spermatogenesis, but testes continued growing, reaching a maximum of all parameters at 70 wk of age, without further major changes at the age of 116 wk. It is concluded that (1) gonadal activation is evident at wk 21, (2) the male marmoset reaches the pubertal threshold around 43 wk of age, attains qualitative parameters at 52 wk, matures further to sexual maturity at 70 wk, and (3) serum testosterone and ITAs are highly variable without any identifiable correlation with pituitary bioCG.

Animals↗
PubMed2005

Fecal androgen levels in common marmoset (Callithrix jacchus) males living in captive family groups.

In captive common marmoset groups, the reproductive inhibition observed in subordinate female seems to be a result of olfactory, visual and behavioral cues from the dominant female. However, few studies have examined the relationship among adult males living in the same social group. These studies have shown that reproductive failure among peer males seems to be based on hormonal and behavioral mechanisms. New insights on sexual strategies in primates have been shown using fecal steroids, but so far no information is available for common marmoset males. In the present study, we evaluated the influence of light-dark cycle, age and reproductive condition on the profile of fecal androgens in males living in the same family group. Feces were collected from six fathers and six sons for androgen determination during the light phase of the 24-h cycle for eight days randomly distributed over a 4-week period. Androgen levels were determined by enzyme immunoassay technique. Adult sons showed higher androgen levels (166.97 +/- 22.95 ng/g) than fathers (80.69 +/- 44.38 ng/g) and juveniles (49.06 +/- 23.15 ng/g; P < 0.05). No diurnal variation (P > 0.05) in fecal androgen profile was observed in adults or juveniles. No indication of androgen-mediated social competition between fathers and adult sons was demonstrable. These results provide basic information on fecal androgen profile useful to investigate the socioendocrinology of free-ranging common marmoset males and verify that, in contrast to daughters, the reproductive suppression of sons is not based on physiological inhibition of their gonads.

Androgens↗
PubMed2005

Density, proportion, and dendritic coverage of retinal ganglion cells of the common marmoset (Callithrix jacchus jacchus).

We performed a quantitative analysis of M and P cell mosaics of the common-marmoset retina. Ganglion cells were labeled retrogradely from optic nerve deposits of Biocytin. The labeling was visualized using horseradish peroxidase (HRP) histochemistry and 3-3'diaminobenzidine as chromogen. M and P cells were morphologically similar to those found in Old- and New-World primates. Measurements were performed on well-stained cells from 4 retinas of different animals. We analyzed separate mosaics for inner and outer M and P cells at increasing distances from the fovea (2.5-9 mm of eccentricity) to estimate cell density, proportion, and dendritic coverage. M cell density decreased towards the retinal periphery in all quadrants. M cell density was higher in the nasal quadrant than in other retinal regions at similar eccentricities, reaching about 740 cells/mm(2) at 2.5 mm of temporal eccentricity, and representing 8-14% of all ganglion cells. P cell density increased from peripheral to more central regions, reaching about 5540 cells/mm(2) at 2.5 mm of temporal eccentricity. P cells represented a smaller proportion of all ganglion cells in the nasal quadrant than in other quadrants, and their numbers increased towards central retinal regions. The M cell coverage factor ranged from 5 to 12 and the P cell coverage factor ranged from 1 to 3 in the nasal quadrant and from 5 to 12 in the other quadrants. These results show that central and peripheral retinal regions differ in terms of cell class proportions and dendritic coverage, and their properties do not result from simply scaling down cell density. Therefore, differences in functional properties between central and peripheral vision should take these distinct regional retinal characteristics into account.

Animals↗
PubMed2001

Ecological aspects of black-pincelled marmoset (Callithrix penicillata) in the cerradão and dense cerrado of the Brazilian central plateau.

Ecological data about three free-ranging groups of C. penicillata (black-pincelled marmoset) were observed between March and December 1996, in one cerradão patch (in the Ecological Reserve of Brazilian Institute of Geography and Statistics, RECOR) and two patches of dense cerrado (one in the RECOR and another in the Botanical Garden of Brasília, JBB), situated in the APA (area of environmental protection) of the Gama/Cabeça-de-Veado, Distrito Federal. Each area was visited weekly during three periods of two months--end of the rainy season (01/04 to 31/05), dry season (16/06 to 15/08) and beginning of the rainy season (14/10 to 15/12)--and instantaneous scan records at fifteen minute intervals were made for the vertical and horizontal position of each visible individual of the target group. The group size ranged between 4 and 11 elements. In September, the birth of twins in both groups of the RECOR was observed. Home-range varied from 8.25 to 18.5 hectares, while density ranged from 0.4 to 0.82 ind/ha. Twenty two species of nine tree families were identified as exudate sources. Qualea grandiflora (Vochysiaceae), Vochysia thyrsoidea (Vochysiaceae), Scheflera macrocarpum (Araliaceae) and Qualea parviflora (Vochysiaceae) were more explored. Fruits (14 species, two of which were exotics), nectar, honey, arthropods (mainly orthopterans) and bird eggs complete their diet. The main sleep-tree species was Emmotum nitens (Icacinaceae). Data from different seasons and studied groups/areas were compared along previous data from this primate species in gallery forests. In the cerradão and dense cerrado areas C. penicillata had a similar group size, however a larger home-range and smaller density than in gallery forests were observed in this study.

Animals↗