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PubMed1992

Dietary fat modulation of left ventricular ejection fraction in the marmoset due to enhanced filling.

OBJECTIVE: The aim was to investigate the influence of long term dietary fish oil consumption on cardiac function in a non-human primate, to elucidate further the basis of the apparently reduced cardiovascular disease mortality associated with its consumption in man. METHODS: Adult male marmoset monkeys (Callithrix jacchus) were fed diets supplemented with polyunsaturated fatty acids (PUFA) of marine (tuna fish oil) or plant (sunflower seed oil) origin, saturated animal fat (sheep perirenal fat), or a low fat reference diet for 24 months. Cardiac function was assessed using radionuclide angiography under pentobarbitone anaesthesia with a counts based adaptation for ventricular volume estimations. Measures were made at rest and during infusion of adrenaline. RESULTS: The mean left ventricular ejection fraction was greater in the tuna fish oil group [55.0(SEM 1.1)% n = 7] and the sunflower seed oil group [58.1(2.4)% n = 8] than in the reference group [48.5(1.4)% n = 9] and the sheep fat group [47.6(1.8)% n = 8]. This was associated with a more than 25% greater end diastolic volume and 40-70% increases in stroke volume in tuna fish or sunflower seed oil fed animals. There was no evidence of cardiac hypertrophy. In contrast, adrenaline increased stroke volume and ejection fraction by increasing emptying, thus reducing residual end systolic. Tuna fish oil fed animals had a low resting heart rate. When this was raised to comparable levels by adrenaline, lower pressure-rate indices and greater cardiac minute work suggested higher myocardial energy efficiency in PUFA fed animals compared with the reference and sheep fat groups. CONCLUSIONS: Dietary fish oil and sunflower seed oil increased the left ventricular ejection fraction in the marmoset monkey by enhancing ventricular filling, thus providing an energy sparing promotion of diastolic relaxation.

Animals↗
PubMed1993

A T.E.M. stereological analysis of blood vessels and nerves in marmoset periodontal ligament following endodontics and magnetic incisor extrusion.

Maxillary incisor fracture is a common dental injury. It is frequently treated by endodontic therapy, orthodontic extrusion, and a retention period. The aim of the study was to mimic this regime and stereologically quantify the vascular and neural reconstitution of the periodontal ligament (PDL). Ten marmosets (Callithrix jacchus) had the right maxillary incisor crown removed, root canal treatment, and magnetic incisor root extrusion of 1.2 mm. After incisor retention for 9 weeks, the animals were perfusion fixed for electron microscopy. The incisor PDL was sectioned at 250 micron intervals from the cervical to apical region and recorded for stereological evaluation. Further evaluations were conducted with a two-way analysis of covariance using program 3V of the BMDP-81 statistical software package. The total luminal PDL vascular volume was statistically unchanged. An increased occurred in the mean number of venous capillaries from 0.07 +/- 0.3 to 0.17 +/- 0.3 per 560 microns 2 of PDL (P < 0.05). Vessel wall and luminal volume of post-capillary-sized venules decreased from 1.64 to 1.03 per cent, and 5.32 to 3.04 per cent (P < 0.05), respectively. Mean luminal and abluminal diameters for post-capillary-sized venules were reduced (P < 0.05). Myelinated and unmyelinated axons showed no significant change in volume (Vv), length (Lv), or surface (Sv) densities. Axon number/unit, PDL area, and mean diameters demonstrated no statistical differences. Since the PDL demonstrated almost complete morphological re-establishment of the microvascular and axon systems, it is considered that this clinical treatment is a justifiable rationale.

Analysis of Variance↗
PubMed1997

Location and developmental regulation of androgen receptor in primate ovary.

Locally produced androgens act via granulosa cell androgen receptors to modulate follicular responsiveness to gonadotrophins and thereby contribute to the paracrine regulation of ovarian function. We used quantitative androgen receptor immunocytochemistry to assess androgen receptor distribution in relation to pre-ovulatory follicular development in the common marmoset (Callithrix jacchus), a New World primate that ovulates two to four follicles in each approximately 28 day ovarian cycle. Ovaries from four adult females in the late follicular phase and from four in the luteal phase were fixed in 4% paraformaldehyde and subjected to an immunocytochemical analysis using a polyclonal androgen receptor antibody with detection by a standard avidin-biotin-peroxidase technique for alkaline phosphatase. Specific androgen receptor immunostaining occurred mainly in granulosa cell nuclei, with little or no specific staining in theca, stroma or oocytes. Granulosa cell androgen receptor immunostaining was most abundant in healthy preantral/early antral follicles, being low or absent from pre-ovulatory follicles and corpora lutea. Differences in granulosa cell androgen receptor immunostaining between immature (0.1-1.0 mm diameter) and pre-ovulatory (> or = 2.0 mm diameter) follicles were quantified using a videodensitometric analysis of grey-scale values. Readings were taken from the granulosa cell layers of 53 immature follicles and 10 pre-ovulatory follicles in late follicular phase ovaries. The average androgen receptor level in granulosa cells of immature follicles proved to be 4.2-fold higher (P < 0.01) than that in granulosa cells of pre-ovulatory follicles. Because other evidence suggests that paracrine androgen action in granulosa cells converts from stimulation to inhibition as follicles mature, we speculate that a development-related reduction in androgen receptor numbers serves to "protect' granulosa cells against the inhibitory action of androgen, thereby promoting pre-ovulatory follicular dominance in primate ovarian cycles.

Animals↗
PubMed1998

Expression and immunolocalization of the oxytocin receptor in human lactating and non-lactating mammary glands.

The milk ejection reflex is mediated by the release of pituitary oxytocin and its interaction with specific receptors within the mammary gland. Although up-regulation of the oxytocin receptor during lactation has been shown for the rat mammary gland by ligand binding assay, investigation of the receptor expression in human breast at the molecular level has not yet been carried out in detail. Here we report the expression and immunolocalization of the oxytocin receptor in the human breast. It appears that the expression level of the receptor-specific mRNA is not significantly elevated during lactation and the protein remains at a relatively low level. However, this lack of increase may be only a dilution effect because of the high level of milk protein expression. Immunohistochemistry and immunoelectron microscopy using three anti-oxytocin receptor antibodies raised against different epitopes of the receptor indicated the presence of receptor immunoreactivity only to a very limited extent in the myoepithelial cells; more specific expression appeared to occur in the ductal/glandular epithelium in both the non-lactating as well as lactating breast. This finding was also confirmed in a New World monkey, the common marmoset (Callithrix jacchus). These results suggest that, at least for human and marmoset, in addition to--or even instead of--myoid cells, the ductal/glandular epithelium is also a target for oxytocin action, not only during lactation but also in the non-lactating breast. Thus, there may be other physiological effects of oxytocin besides direct myoid cell contraction in the breast.

Adult↗
PubMed1984

Infectious mononucleosis-like response in common marmosets infected with Epstein-Barr virus.

Callithrix jacchus marmosets infected with Epstein-Barr virus (EBV) with or without concurrent treatment with cyclosporin A (CySA) remained healthy. Five marmosets given virus alone developed lymphocytosis and heterophile antibody. Antibody to EBV capsid antigens (VCA) appeared and remained at titers of 1:40-1:80 from 15 weeks onward. Two animals produced antibody to the R component of early antigens (EA) from six weeks onward. Five CySA-treated EBV-infected marmosets showed no increase in total lymphocyte counts; only two developed heterophile antibody. Four developed persistent antibody to the EA-R component. All developed antibody to VCA, and mean titers were higher than in animals given EBV alone. Antibody to VCA also appeared in animals given EBV into Waldeyer's ring. Because these responses to EBV resemble those of humans, C. jacchus may provide a useful model for exploring the potential of cofactors in inducing EBV-associated malignancy.

Animals↗
PubMed1988

Glomerulonephritis in common marmosets infected with Plasmodium brasilianum and Epstein-Barr virus.

Plasmodium brasilianum causes chronic quartan malaria in the common marmoset Callithrix jacchus, whereas Epstein-Barr virus (EBV) infection is followed by an infectious mononucleosis-like syndrome that resolves. We infected weanling marmosets with one or both of these pathogens. Timing of the infections influenced outcome. Six animals were simultaneously infected with both agents; four became seriously ill (with accompanying proteinuria and edema) and either died or were killed. Histopathology indicated that glomerulonephritis had developed. The two survivors had more-prolonged parasitemia than did animals infected with P. brasilianum alone, as did animals infected with EBV before P. brasilianum. Five of the six simultaneously infected animals had absent or low titers of antibody to Epstein-Barr viral capsid antigens when compared with the other EBV-infected animals. Our results suggest that combined infection may be part of the etiology of quartan malarial nephropathy.

Animals↗
PubMed1994

3H11, a unique cell surface molecule involved in the function of the CD45RA+ subset of CD4+ cells.

We have developed a mAb anti-3H11 by immunizing mice with a T cell line derived from the Callithrix jacchus (common marmoset). Anti-3H11 is reactive with approximately 48% of unfractionated T cells, 62% of CD4+ cells and 39% of CD8+ cells. Among CD4 cells, anti-3H11 preferentially reacts with the CD45RA+ T cell subset. The majority of helper activity for pokeweed mitogen (PWM)-driven B cell IgG synthesis and T cell response to recall antigen such as tetanus toxoid was found within the 3H11-CD4 cell population, whereas anti-3H11+CD4+ cells provided poor helper function for PWM-driven B cell IgG synthesis and were more responsive to concanavalin A and autologous mixed lymphocyte reaction. Biochemical characterization showed that anti-3H11 precipitated a single protein band with a relative molecular weight of 32,000 from 125I-surface labeled cell lysate. Biochemical, phenotypic and functional studies revealed that the 3H11 molecule appeared to be different from previously established molecules on the T cell surface. Interestingly, addition of anti-3H11 to the combination of CD4 and B cells in the presence of CD8 cells but not to the combination of CD4 and B cells resulted in enhancement of the suppression of PWM-driven B cell IgG synthesis. Moreover, anti-3H11 had a co-mitogenic effect on T cells via the CD2 and CD3 pathways, and this co-mitogenic activity is restricted to the CD45RA+ T cells. Taken together, our results show that the 3H11 molecule is a novel antigen which may play an important role in the activation and function of the CD45RA+ subset of T cells.

Animals↗
PubMed2001

Subtoxic hepatic vitamin A concentrations in captive rhesus monkeys (Macaca mulatta).

Although the rhesus monkey (Macaca mulatta) is a widely used experimental animal, its exact vitamin A requirement is unknown. An amount of 430-3600 IU/d [129-1080 retinol equivalents (RE)] is recommended, largely on the basis of depletion studies. Normal hepatic vitamin A appears to be 1 micromol/g liver. Our goal was to determine hepatic vitamin A concentrations of captive monkeys. Liver autopsy samples from rhesus and marmoset (Callithrix jacchus) monkeys were obtained from the Wisconsin Regional Primate Research Center. The rhesus monkeys consumed a diet with 40 IU (12 RE) retinyl acetate/g. Male and female monkeys consumed an estimated 250 and 175 g diet/d, respectively. Marmosets were fed a powder-based diet consisting of 20 IU (6 RE) retinyl acetate/g. The marmosets consumed an estimated 25 g of the diet/d. Liver samples were extracted and analyzed by HPLC. The vitamin A concentration of the rhesus monkey livers was very high at 17.0 +/- 6.3 micromol/g. The hepatic vitamin A of the marmosets was 1.25 +/- 0.58 micromol/g liver. Histologic examination of the livers revealed Ito cell hypertrophy and hyperplasia in the rhesus monkeys compared with the marmosets. Considering that the natural diet of the rhesus monkey (fruits, seeds, roots and insects) is not high in preformed vitamin A, the vitamin A content of the diet appears excessive, supplying four times the NRC recommendation and resulting in high liver stores.

Animals↗
PubMed1999

Design and evaluation of a ZP3 peptide vaccine in a homologous primate model.

The concept of a safe, immunocontraceptive vaccine using the zona pellucida glycoprotein 3 (ZP3) as an immunogen has been marred by the appearance of ovarian dysfunction in several species. However, careful selection of epitopes on mouse ZP3 have demonstrated that it is possible to segregate contraceptive bone marrow-derived (B)-cell epitopes from the cytotoxic thymus-derived (T)-cell epitopes thought to be responsible for inducing ovarian disease. B-cell epitopes on marmoset ZP3 (mstZP3) were identified by epitope mapping studies. Using a panel of polyclonal antibodies against recombinant mstZP3, an immunodominant epitope mstZP3(301-320) was identified. A chimeric peptide was co-linearly synthesized incorporating this sequence with a promiscuous tetanus toxoid T-helper cell epitope. Using the common marmoset (Callithrix jacchus) as an animal model, we have compared the consequences of active immunization with homologous recombinant mstZP3 and mstZP3(301-320) chimeric peptide vaccine. Long-term infertility was achieved using mstZP3 but at the expense of ovarian function. In contrast, no disruption to ovarian function was observed following mstZP3(301-320) immunization. Antibodies to this peptide immunolocalized to the zona pellucida of both marmoset and human ovarian sections and inhibited human sperm-zona binding by approximately 60% in vitro. However, in-vivo studies indicated that targeting a single ZP3 epitope was insufficient to reliably and consistently achieve a contraceptive effect.

Animals↗
PubMed1988

Expression of C-type viral particles at implantation in the marmoset monkey.

Type C RNA retroviral particles have been observed budding from the plasma membrane of syncytiotrophoblast during a study of embryo implantation in the common marmoset (Callithrix jacchus). These viral particles appear in profusion at the interface of syncytiotrophoblast with cytotrophoblast. They appear to be a non-infective, endogenous viral component of the host genome, although the precise role of the C-type virus in this context is unclear at present. Such viral particles have been reported previously from studies of human term placenta; however, this is the first report indicating that expression of viral particles occurs at the earliest stages of embryo implantation.

Animals↗
PubMedDate not supplied

Genetic and environmental impacts on litter size and early infant survival in three species of callitrichids.

Callitrichids are unusual among anthropoid primates in that they can deliver one to four offspring per litter in captivity. Factors underlying intraspecific variation in litter size are unclear. Data from the Oak Ridge Associated Universities (ORAU) Marmoset Research Center provided an opportunity to investigate determinants of variation in (1) average litter size at birth and (2) average litter size surviving to 2 weeks of age in Saguinus fuscicollis, S. oedipus, and Callithrix jacchus. The objectives were to (1) investigate the impact of parity, husbandry, origin (wild or captive), and subspecific hybridization on phenotypic variance in litter size and (2) to estimate the heritability of litter size at birth and at 14 days. Husbandry changes were the only significant covariate and increased litter size at birth in C. jacchus only. Heritability estimates for average litter size at birth were significant only in S. fuscicollis (h2 = 0.306). Heritability of average litter size at 2 weeks of age was not significantly greater than zero. Estimates of genetic variability were relatively high, however both traits had very high levels of residual variance. The results suggest that litter size is a malleable trait that may respond to environmental factors.

Animals↗
PubMed1997

Marmoset phylogenetics, conservation perspectives, and evolution of the mtDNA control region.

Marmosets (genus Callithrix) are a diverse group of platyrrhine primates with 13-15 purported taxa, many of them considered endangered. Morphological analyses constitute most of the basis for recognition of these forms as distinct taxa. The purpose of this study was to provide a molecular view, based on mitochondrial control region sequences, of the evolutionary history of the marmosets, concomitant with a molecular phylogenetic perspective on species diversity within the group. An additional purpose was to provide the first comparative examination of a complete New World monkey control region sequence with those of other mammals. The phylogenetic analyses provide convincing support for a split between the Atlantic forest and Amazonian marmosets, with the inclusion of the pygmy marmoset (Cebuella pygmaea) at the base of the Amazonian clade. The earliest branch of the Atlantic forest group was C. aurita. In the Amazonian group, the analyses do not support the recognition of C. humeralifer and the recently described C mauesi as distinct taxa. They do, however, support a clear distinction between C. argentata and a strongly supported mixed clade of C. humeralifer and C. mauesi. In the Atlantic forest group, the phylogenetic tree suggests mixing between C. penicillata, C. kuhli, and possibly C. jacchus. Most of the sequence features characteristic of other mammal control regions were also evident in marmosets, with the exception that conserved sequence blocks (CSBs) 2 and 3 were not clearly identifiable. Tandem repeat units often associated with heteroplasmy in a variety of other mammals were not evident in the marmoset sequences.

Animals↗
PubMed2000

Effects of dietary oltipraz and ethoxyquin on aflatoxin B1 biotransformation in non-human primates.

Following aflatoxin B1 (AFB) exposure, rats readily develop liver tumors. However, treatment of rats with a variety of compounds, including the synthetic dithiolthione oltipraz and the antioxidant ethoxyquin, protects these rodents from AFB-induced hepatocarcinogenesis. Several epidemiological studies strongly suggest that AFB is also a causative agent of liver cancer in humans. However, relatively little is known about the efficacy of cancer chemoprevention in human and non-human primates. To this end, we examined the effects of chemopreventive agents on AFB metabolism in non-human primates. Hepatic aflatoxin B1 metabolism profiles of macaque (Macaca nemestrina) and marmoset (Callithrix jacchus) monkeys were determined and compared to humans. Quantitatively, the oxidative metabolism of this mycotoxin was similar in the three primate species. In contrast to macaques, both humans and marmosets lacked AFB-glutathione conjugating activity. It was concluded that marmosets resembled human AFB metabolism more closely than the macaques, and therefore, marmoset monkeys were chosen for this study. Eleven adult male marmosets were randomly assigned to three groups. Animals received the synthetic dithiolthione oltipraz, the antioxidant ethoxyquin, or vehicle only. In addition, two single doses of AFB were also administered orally before and after animals were treated with aforementioned compounds. Both oltipraz and ethoxyquin induced aflatoxin B1-glutathione conjugating activity in the livers of some but not all marmosets. In addition, 10 microM oltipraz inhibited cytochrome P450-mediated activation of AFB to the ultimate carcinogenic metabolite, aflatoxin B1-8,9-epoxide, in vitro, up to 51%. Furthermore, animals treated in vivo with oltipraz, but not ethoxyquin, exhibited a significant reduction (53% average) in AFB-DNA adduct formation relative to the control animals (p < 0.05). Together, our data suggest that chemoprevention is also effective in primates; however, most likely to a lesser degree than in rodents.

Aflatoxin B1↗
PubMed2003

Characterization of 17beta-hydroxysteroid dehydrogenase type 7 in reproductive tissues of the marmoset monkey.

In contrast to the known rodent enzymes, the physiological significance of 17beta-hydroxysteroid dehydrogenase type 7 (17HSD7) and its presumed function in reproductive biology is not well understood in primates. As a first step, we recently cloned the complete coding regions of human and marmoset monkey (Callithrix jacchus) 17HSD7 (cj17HSD7). In the present work the complete cDNA of marmoset 17HSD1 (cj17HSD1), including the proximal promoter region, and a partial sequence of marmoset aromatase (cjARO) were sequenced in order to compare the expression of these estradiol synthesizing enzymes with that of 17HSD7 in a primate model and to identify tissues where 17HSD7 might participate in the pathway of estradiol synthesis. The gene structures of cj17HSD1 and cj17HSD7 were determined and proved to be very similar to the human orthologues. Northern hybridization showed that cjARO mRNA seems to be coexpressed preferably with cj17HSD1 in placenta, whereas in other tissues it is expressed in parallel only with cj17HSD7. Especially in corpora lutea, the cj17HSD7 transcript is detectable throughout the luteal phase of the ovarian cycle and increases during pregnancy, in parallel with the transcript of aromatase. Results were confirmed by immunoblots and immunohistochemistry using new polyclonal antisera directed against cj17HSD7 and cjARO protein. The enzymatic conversion of estrone to estradiol was assessed in marmoset corpora lutea. The pattern of coexpression with aromatase supports the hypothesis that luteal 17HSD7 complements placental 17HSD1, ensuring continued estradiol synthesis throughout pregnancy in primates.

17-Hydroxysteroid Dehydrogenases↗
PubMed1995

Meiotic competence of marmoset monkey oocytes is related to follicle size and oocyte-somatic cell associations.

This study was conducted to investigate the relationships between oocyte meiotic competence, follicle size, and occyte-somatic cell associations in the marmoset monkey (Callithrix jacchus). Follicles were excised from ovaries of nonstimulated adult cyclic females (n = 6) collected on Day 7 of the follicular phase. Follicles were separated into size groups: large preantral (260-400 microns), periantral (420-640 microns), small antral (660-1000 microns), large antral (1020-2000 microns), and preovulatory (> 2000 microns). Partially naked and cumulus/granulosa-enclosed oocytes (n = 473) were released from follicles and cultured in Waymouth's medium with 10% fetal calf serum, 1 microgram/ml human (h) FSH, and 10 micrograms/ml hLH. Somatic cells remaining after 46 h were removed, and oocytes were fixed after 48 h and mounted for viewing. Chromatin staining and microtubulin fluorescence labeling were used to assess progression of meiotic maturation and spindle normality. The follicle size distribution and oocytesomatic cell associations are reported. Competencies of oocytes to achieve germinal vesicle breakdown (GVBD) and metaphase II (MII) increased significantly (p < 0.001) with follicular size but not with the association of somatic cells. Marmoset oocytes from antral follicles resumed (GVBD) and completed (MII) meiotic maturation with high frequencies (98% and 72%, respectively), with no significant differences among size groups of antral follicles. GVBD competence was virtually absent in oocytes from preantral follicles (2%) and was acquired coincidentally with antrum formation (60%), although MII competence was attained after the completion of antrum formation. Partially naked oocytes from small antral follicles matured with a high incidence of spindle and meiotic abnormalities (44%). Marmoset oocyte meiotic competencies are notably higher than in any other nonhuman primate species studied, and a possible explanation for this phenomenon in relation to the stage of antrum formation is offered.

Animals↗
PubMed1997

Oxytocin and oxytocin receptor expression in reproductive tissues of the male marmoset monkey.

Using a combination of reverse transcriptase polymerase chain reaction to detect specific mRNA and immunohistochemistry employing antibodies that recognize two different epitopes for each molecule, the local production of oxytocin (OT) and its cognate receptor was investigated in the male marmoset monkey (Callithrix jacchus). There was synthesis of both OT and the oxytocin receptor (OTR) within the testis, and both were markedly expressed within the Leydig cells. A weak staining for both OT and its associated neurophysin could also be detected in Sertoli cells in some animals. Expression of OT or neurophysin does not appear to be significant in the epididymis, though there appears to be synthesis of the receptor in some peritubular muscle cells of the epididymis and in the vas deferens. Within the prostate, there appears to be no production of OT or neurophysin, though there appears to be weak expression of the OTR in the basal layers of the secretory epithelium. Similarly in the bulbourethral gland, only OTR immunoreactivity could be detected. Receptors appear to be present in the myoid cells encompassing the glandular lobules and are presumably able to respond to systemic OT. An analysis of juvenile marmosets indicates that the testicular OT system appears to become established during puberty. Thus, in this New World monkey the testis is able to support a local OT-based paracrine-type system, though the prostate and bulbourethral gland are probably only able to respond to exogenous OT.

Animals↗
PubMed2000

Effect of neonatal gonadotropin-releasing hormone antagonist administration on sertoli cell number and testicular development in the marmoset: comparison with the rat.

The primary purpose of this study was to establish whether Sertoli cells proliferate in the neonatal period in the marmoset monkey (Callithrix jacchus) and whether administration of a long-acting GnRH antagonist (GnRHa) during this phase induced any transient or permanent effects on Sertoli cell number or on any other aspect of testicular development. Male marmoset co-twins (n = 9) were treated during Weeks 1-14 with either vehicle or GnRHa. Four sets of co-twins were examined at Weeks 18-22 (start of infancy) and 5 sets in adulthood (92+ wk), and Sertoli cell number was determined using either the nucleator or optical disector methods; other testicular morphometric analyses (e.g., germ cell volume, Leydig cell volume) used standard point-counting. Data for the marmoset were compared with that obtained in similarly treated rats. Sertoli cell number in marmosets treated neonatally with GnRHa was reduced by 35% compared with that of controls at Weeks 18-22 but was comparable to control values in adulthood. However, seminiferous epithelium volume was reduced significantly in adult marmosets treated neonatally with GnRHa, and there was a tendency for reduced germ cell volume per Sertoli cell. In the same animals, there was significant expansion of the interstitium and an increase in Leydig cell volume per testis when compared with co-twin controls; a similar increase in Leydig cell volume was evident in adult rats treated neonatally with GnRHa. Comparison of Sertoli cell numbers in 6 infantile (18-24 wk) and 10 adult marmosets showed that adult numbers of Sertoli cells were present by the start of infancy but, unlike rats, marmosets were still able to replicate Sertoli cells beyond this period. However, marmoset Sertoli cells supported only approximately 20% of the germ cell volume supported by rat Sertoli cells, indicative of poor efficiency of spermatogenesis, as shown previously in the human. This finding, together with the demonstration of a temporal pattern of Sertoli cell replication similar to that in the human, supports the use of marmosets as a model for human male testicular development and function.

Aging↗
PubMed2001

Changes in follicle-stimulating hormone and follicle populations during the ovarian cycle of the common marmoset.

The common marmoset (Callithrix jacchus) belongs to the family Callitrichidae, the only anthropoid primates with a high and variable number of ovulations (one to four). An understanding of folliculogenesis in this species may provide some insight into factors regulating multiple follicular growth in primates. The aims of this study were to characterize in detail changes in the antral follicle population at different stages of the ovarian cycle, to characterize the marmoset FSH profile, and to relate cyclic changes in FSH to changes in follicle sizes and circulating estradiol concentrations. Fifty-five pairs of ovaries were collected (32 of which were at five distinct stages of the cycle) from adult marmosets, and antral follicles were manually excised and separated into four size groups. Daily urinary FSH and plasma estradiol and progesterone concentrations from Day 0 of the follicular phase to 2 days postovulation were measured in 22 marmosets using enzyme immunoassays. The FSH profile revealed two distinct peaks, on Days 2 and 6, during the 10-day follicular phase, with a marginal periovulatory increase on Days 9 and 10. Estradiol levels rose significantly (P: < 0.05) above baseline (Days 1-4) on Day 5 and continuously increased to a peak on the day preceding ovulation (Days 8 and 9). Follicle dissection revealed a high (mean = 68) and variable (range, 14-158) total number of antral follicles >0.6 mm. The number of antral follicles significantly declined (P: < 0.001) with age. The number of preovulatory follicles (>2 mm) was positively correlated with the number of antral follicles (P: < 0. 001) and tended to be negatively related to age (P: = 0.06). The number of antral follicles did not vary significantly with stage of the ovarian cycle, although the follicle size distribution was cycle-stage dependent (P: < 0.05). Follicles >1.0 mm appeared only in the follicular phase, and preovulatory follicles (>2.0 mm) appeared only at the end of the follicular phase (Days 7-9). The Day 2 FSH peak corresponded to emergence of a population of medium-size antral follicles, and the Day 6 peak was consistent with rising estradiol levels and appearance of the preovulatory follicles. These results suggest that some aspects of marmoset folliculogenesis are comparable to those in Old World primates, including the absence of multiple follicular waves and the appearance of an identifiable dominant follicle in the midfollicular phase. However, the midphase FSH peak, multiple dominant follicles, and abundance of nonovulatory antral follicles differ strongly from the pattern in Old World primates and humans. The findings are discussed in relation to the regulation of growth of multiple ovulatory follicles and provide the basis for further studies on factors influencing the dynamics of follicular growth and development in this species.

Animals↗