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Plasma aminotransferase values were measured in a large number of samples from male and female marmosets. There were no differences due to age or sex for either AST or ALT. Haemolysis affected values for both enzymes, though the effect on ALT was greater.
This paper describes the finding of a number of malformations in a live-born common marmoset. The malformations included microphthalmia, ocular hypertelorism, cleft lip and palate and polydactyly. The findings are consistent with and strongly suggest chromosome trisomy similar to that which has been seen in man.
This paper describes previously unreported malformations of both fore and hind feet in a liveborn common marmoset. Ectrodactyly of both fore feet and left hind foot and syndactyly of the right hind foot were observed.
We have used our laboratory records to compare data on the reproduction and maintenance of common marmosets in different colonies and to provide additional information on the species in captivity. Data are presented for a period of 12 years. This was long enough to allow information on longevity, mortality, aggression and incest. In addition 543 infants were born from a total of 202 births. No seasonality was found and the highest proportion of births overall was that of triplets. A significantly greater proportion of males was born, but perinatal mortality reduced this to a proportion of 52.2% surviving males. The interbirth interval for all normal births ranged from 145 to 382 days, with a median of 158 days. There was no evidence that interbirth intervals increased with age. The proportion of non-breeding pairs was small (4 out of 28) and progesterone assays showed that these females were ovulating.
A method for restraining the marmoset in a primate chair is described. The device is inexpensive to construct, is reliable, and the majority of animals can be habituated to its use. The chair has been used in neurobiological studies employing electrophysiological recordings, with or without concurrent collection of serial blood samples.
A congenital abnormality of the digits, similar to the 'lobster claw' deformity of humans, was observed in 8 common marmosets. The condition varied in severity and in effect on the animals; it appeared to be due to a single autosomal recessive trait.
The way in which breeding families of laboratory-born marmosets used the space provided by their cages, and a small protruding 'veranda', was assessed in order to determine the popularity of the veranda as a form of environmental enrichment, and the extent to which the marmosets confined themselves to only part of the cage. The veranda was found to be of enduring interest to the marmosets whose occupancy of this space was an order of magnitude greater than the rest of the cage. The upper part of the cage was preferred to the bottom half. This preference was greater in larger cages and decreased when larger cages were temporarily reduced in size. It is unlikely, however, that the distribution of the occupancy of different parts of the cage resulted primarily from a fear of people in the holding room. The veranda, which was the most preferred place in the cage, was the nearest part of the cage to people in the room. Occupancy of the lower part of the cage increased when human observers sat on the floor, suggesting that some of the marmosets' behaviour comprised approaching, rather than avoiding, the observers, possibly for reasons of curiosity and social interaction.
To determine drug-induced hyperfunction of marmoset thyroids due to inhibition of synthesis or enhancement of metabolic elimination of thyroid hormones, males were orally administered 10 and 30 mg/kg/day methimazole (MMI), 30 and 100 mg/kg/day spironolactone (SPL), or 50 mg/kg/day phenobarbital (PB) for 4 weeks. MMI caused marked hypertrophy of follicular epithelial cells in accordance with a significant decrease in the plasma thyroxin (T4) level. Hypertrophied epithelial cells were filled with dilated rough endoplasmic reticulum and reabsorbed intracellular colloids, and the luminal surface was covered with abundant microvilli. The colloid included vacuoles positive to anti T4 immuno-staining. SPL and PB also caused similar histomorphological changes, although they were less severe than those due to MMI and were not clearly associated with decrease in the plasma T4 levels. Hepatic T4 UDPGT activities tended to increase due to SPL and PB treatment, however, which were not so significant as increases in microsomal cytochrome P-450 contents. Some animals treated with SPL and PB showed marked increases in thyroid weights due to inactive dilated follicles. In conclusion, hyperactivity of thyroid follicles was induced in marmosets not only due to inhibition of T4 synthesis produced by MMI but also because of enhancement of hepatic T4 elimination produced by SPL and PB. However, hypertrophic effects of SPL and PB were less severe than MMI, because plasma T4 levels were maintained at almost pretreatment or control levels after SPL or PB treatment.
A heterologous double-antibody radioimmunoassay was used to measure plasma prolactin concentrations in 27 marmosets. The assay was valid for the marmoset because plasma levels of prolactin were increased in response to TRH and metoclopramide and suppressed in response to bromocriptine treatment. During the cycle there were no consistent changes in plasma prolactin concentrations. During lactation mothers suckling single or twin infants had higher prolactin levels than did non-suckling females and levels were highest with twins. No statistically significant delay in the resumption of ovulation post partum was observed for the suckling and non-suckling females; conception occurred in all but one marmoset by 70 days post partum. These results show that neither the suckling stimulus nor high levels of prolactin post partum delay the return of ovulation and fertility in the common marmoset, a result in contrast to that for all other primate species so far investigated.
Plasma concentrations of progesterone, cortisol, LH and prolactin were measured in dominant and subordinate female marmosets in 10 well-established peer groups. Subordinate females never ovulated, had a reduced LH response to LH-RH and showed no positive feedback LH surge after oestrogen administration. There was no evidence of elevated plasma cortisol levels or hyperprolactinaemia in subordinates and all showed a similar prolactin response to TRH in comparison with dominants. However, subordinates showed a reduced prolactin response to metoclopramide. These results clearly indicate that high circulating levels of cortisol or prolactin are not responsible for the inhibition of ovulation in female marmosets.
In adult animals the intramuscular injection of hCG was followed by a rapid rise in plasma testosterone levels within 2-3 h and at doses of 40 and 80 i.u. hCG this primary response was followed by a second peak of testosterone at 48 h. Prepubertal marmosets also responded to hCG stimulation with a rapid increase in plasma testosterone levels within 3 h, but the magnitude of this peak was lower than that observed in adult animals and no biphasic pattern was observed. In adult and prepubertal animals a second dose of hCG (40 i.u.) administered 24 h after the initial injection failed to produce a further rapid increment in plasma testosterone levels.
Concentrations of progesterone, 17 alpha-hydroxyprogesterone, oestrone and oestradiol-17 beta in peripheral and utero-ovarian vein blood were measured during the first 60 days of pregnancy. The same hormones were also measured in peripheral blood samples from non-fertile cycles. Peripheral levels of 17 alpha-hydroxyprogesterone, oestrone and oestradiol increased gradually during early pregnancy whereas concentrations of progesterone declined. The patterns of secretion of progesterone, 17 alpha-hydroxyprogesterone and oestrone, but not oestradiol, were significantly different in fertile and non-fertile cycles by 15 days after ovulation. Comparison of hormone values in peripheral and utero-ovarian vein samples from ovaries with and without corpora lutea (Days 7, 9, 13, 21, 40 and 60 of pregnancy) showed that: (a) progesterone was secreted by the corpus luteum until at least Day 40 by which time there was also placental secretion; (2) although 17 alpha-hydroxyprogesterone was secreted by the corpus luteum, the relative contribution of luteal and placental secretion after Day 21 was not clear; (3) oestrone secretion by the corpus luteum was no longer detectable by Day 40, but placental oestrone secretion appeared to be present by this time; (4) the corpus luteum did not secrete significant amounts of oestradiol at any stage of early pregnancy, although there was evidence for placental secretion by Day 40. These results suggest that progesterone secretion by the corpus luteum of early pregnancy continues beyond the time when oestrogen secretion has declined. The corpus luteum to placental shift in the marmoset appears to occur at a later stage of pregnancy than it does in the macaque monkey and probably also in man.
A single intramuscular injection of 0.5 micrograms cloprostenol was not luteolytic on Day 6 or 7 of the ovarian cycle (N = 3), but was luteolytic in some animals (3/5) on Day 8 and 9 and luteolytic in all 23 animals treated between Days 10 and 17 of the ovarian cycle, and in 7 animals treated between Days 19 and 43 of pregnancy. Luteal function was monitored by measurement of progesterone in peripheral blood using a simple and rapid non-extraction assay. There was a dramatic fall in peripheral blood progesterone to less than 10 ng/ml within 24 h of cloprostenol injection; progesterone remained at this low level until the day after post-treatment ovulation. The interval from cloprostenol injection to ovulation in animals treated between Days 8 and 17 was 10.7 +/- 0.3 days. A similar interval was found in pregnant animals. Embryos recovered from the uterus after cloprostenol treatment were morphologically normal (23/24).
Embryos were collected at the 4-10-cell stage from the oviducts (Day 4; Day 1 = ovulation) or as morulae (Day 7) from the uterus of marmosets and frozen in 1.5 M-DMSO (Days 4 and 7) or 1.0 M-glycerol (Day 4 only), using a slow freezing and thawing technique. Of 22 Day-4 embryos frozen in DMSO, 18 were recovered and 16 of these were transferred to 10 synchronized recipients; 7 recipients became pregnant compared with all 7 control recipients receiving 10 unfrozen embryos. Fifteen frozen-thawed morulae were transferred to 9 Day-6 recipients; the pregnancy rate (55.6%) was lower than for control embryos (85.7%). Embryos frozen in glycerol suffered severe osmotic stress during glycerol addition and removal. Of 8 recipients, 3 (37.5%) became pregnant but only one fetus was carried to term. These results on embryo collection, freezing and transfer in the marmoset have important implications for developing improved methods for freezing human embryos and the breeding of endangered primates.
A biologically active gonadotrophin has been purified from the media of long-term cultures of trophoblast cells of the common marmoset monkey by a combination of precipitation and chromatography. Marmoset chorionic gonadotrophin (CG) is a glycoprotein which binds Concanavalin A and wheat germ agglutinin. The protein purified from culture media exists as several isoelectric species with pI in the range pH 3.5-4.5. On gel filtration it eluted with an apparent molecular weight of 68-72,000 but on PAGE migrated as if it was 58-65,000. A glycoprotein with similar characteristics has been recovered from plasma samples of pregnant marmosets. Biological activity of partly purified CG from media, as determined by a mouse testicular cell bioassay, was 1-3 i.u./mg protein.
Doses of 100 or 200 micrograms of a novel GnRH antagonist ([N-acetyl-D beta Na11-D-pCl-Phe2-D-Phe3-D-Arg6-Phe7-Arg8-D-Ala10]NH2 GnRH) (4 animals/dose) were administered on Days 10/11 of the luteal phase and induced a marked suppression of circulating bioactive LH and progesterone concentrations within 1 day of treatment (P less than 0.01). Thereafter, progesterone concentrations remained low or undetectable until after the next ovulation. Similar results were obtained when 200 micrograms antagonist were given on Days 5/6 of the luteal phase (N = 4). The interval from injection of antagonist (200 micrograms but not 100 micrograms) to ovulation (based on a rise in progesterone above 10 ng/ml) was significantly longer than that from prostaglandin-induced luteal regression to ovulation in control cycles (N = 4/treatment) (range, 13-15 days after antagonist vs 8-10 days after prostaglandin, P less than 0.01). This delay of 4-5 days was equivalent to the duration for which LH concentrations were significantly suppressed by 200 micrograms antagonist when administered to ovariectomized animals (N = 3). Corpus luteum function during the cycle after GnRH antagonist treatment appeared normal according to the pattern of circulating progesterone. These results show that corpus luteum function and preovulatory follicular development in the marmoset monkey are dependent on pituitary gonadotrophin secretion.
Six long-term ovariectomized adult marmoset monkeys were treated at 0 h with 35 micrograms oestradiol benzoate s.c. to induce an LH surge. They were also treated with detirelix (an LHRH antagonist) at 0 h, 12 h and 24 h (Exp. 1), or at 0 h and 24 h (Exp. 2) at a dose of 300 micrograms/kg s.c., or received the detirelix vehicle alone at 0 h, 12 h and 24 h (Exp. 3). All animals received the three treatments, with at least 4 weeks between experiments. Blood samples were collected at 0 h and at 6-12 h intervals for 72 h after oestradiol for the determination of plasma LH by bioassay. In control animals, oestrogen treatment resulted in a decline in plasma LH from 30.0 +/- 5.8 at 0 h to 12.8 +/- 2.6 ng/ml at 6 h (negative feedback), followed by a positive feedback surge, reaching a maximum of 148.0 +/- 34.6 ng/ml at 24 h. Values then declined to pretreatment levels by 56 h. In contrast, antagonist-treated animals showed complete abolition of the expected increase at 24 h, the low levels of the negative feedback phase being maintained for 36-72 h. These results show that hypothalamic LHRH release is essential during the oestrogen-induced LH surge, and that a direct oestrogen-induced component at the pituitary level is not expressed in the absence of LHRH in the marmoset.
Dispersed marmoset luteal cells were incubated for 2 h and progesterone production measured after exposure to hCG, cloprostenol, dibutyryl cAMP, PGF-2 alpha, PGF-2, adrenaline or melatonin. The cells were studied on Days 6, 14 and 20 after ovulation in conception and non-conception cycles. Luteal cells from Day 14 non-pregnant marmosets were compared with human luteal cells taken in the mid-luteal phase. All the treatments stimulated progesterone production including cloprostenol, which is luteolytic when administered to the marmoset in vivo, but the degree of response varied with the stage of the cycle or pregnancy and between marmoset and human luteal cells. In the marmoset, overall analysis of the effect of the treatments showed that, on Day 6 after ovulation, there was no significant effect of any of the treatments in cells from pregnant or non-pregnant animals. In contrast, luteal cells from non-pregnant animals on Day 14 showed a significant response to the treatments (F (8,41) = 2.79, P less than 0.0145) whereas cells from pregnant Day-14 animals were responsive; in cells from pregnant animals, the control production of progesterone was high and already equivalent to the levels stimulated by the treatments. By Day 20, cells from pregnant animals produced lower control concentrations of progesterone than did those on Day 14 and there was a significant overall effect of the treatments (F (8,33) = 3.78, P less than 0.003). These results show that the marmoset CL gains responsiveness to treatment between Days 6 and 14 after ovulation in the non-pregnant cycle. In pregnancy, on Day 14, 2 days after attachment of the embryo, the high control concentrations of progesterone and absence of response to treatment suggest that an embryo message may have affected the CL, providing an endogenous stimulus.