Biomedical subjects

R W Rose

Publications and source records attributed to R W Rose.

13 recordsLinked to original sources

PubMed1992

Plasma progesterone levels in the pregnant female rat-kangaroo (Bettongia gaimardi).

Plasma progesterone levels were measured in female bettongs (small macropodid marsupials) under two natural regimes: (1) during "delayed" gestation (initiated by removal of pouch young, RPY) and (2) during the pregnancy prior to pouch vacation when a young still occupies the pouch (i.e., during lactation). Basal levels of progesterone were 0.15-0.5 ng/ml. There was a transient peak of progesterone (0.7 ng/ml) early in gestation at Day 4 RPY. After Day 6 RPY, progesterone levels remained elevated (1.2-1.5 ng/ml) until they dropped sharply to basal levels on the day of birth. This pattern of progesterone secretion during delayed gestation is similar to that seen in other marsupials, such as the tammar wallaby. There was no significant difference between the progesterone profiles of the two experimental groups. We deduce, then, that lactation had no effect on corpus luteum function (as assessed by plasma progesterone levels) in the pregnant bettong.

Analysis of Variance↗

PubMed1992

Maternal recognition of pregnancy in the Tasmanian bettong, Bettongia gaimardi (Marsupialia: Macropodoidea).

The fetus of the marsupial Bettongia gaimardi, the Tasmanian bettong, has both morphological and cytological effects upon the gravid uterus. Development of diapausing embryos or the initiation of oestrous cycles was achieved by removal of the pouch young (RPY). Increases in the diameter of the uterine basal endometrial glands were noted 3 and 4 days later. An animal at Day 5 after RPY had glands in the gravid uterus that were significantly larger than those in the non-gravid uterus (P less than 0.01). This difference was also found in non-pregnant animals before Day 11 and was believed to be due to the local presence of the corpus luteum. Thereafter, significant differences were only found in pregnant animals until parturition at Day 17 or 18 after RPY. These differences were attributed to the local effect of the fetus and reflect a 'maternal recognition of pregnancy', as found in other macropodoid species.

Animals↗

PubMed1991

Testosterone levels in the Tasmanian bettong (Bettongia gaimardi).

The Tasmanian bettong (Bettongia gaimardi) is a small macropodid marsupial that is a continuous breeder. This study has partitioned testosterone into three fractions that vary to some extent throughout the year, coinciding with peaks and troughs in breeding, body weight, and testes volume. The three fractions determined were free, albumin bound, and sex hormone binding globulin (SHBG) bound testosterone. Concentrations of both albumin and SHBG varied significantly throughout the year with peaks in SHBG coinciding with lowered levels of free testosterone. Testosterone was also measured during maturation of male bettongs. There were significant regressions between weight or testes volume and the combined free and albumin bound testosterone. Maturity started near age 30 weeks and a body weight of 1.5 kg and was accompanied by a brief surge in testosterone levels.

Aging↗

PubMed1988

Comparative lactation in two species of rat-kangaroo (Marsupialia).

1. Milk composition and energy content was measured in two related marsupials, Bettongia gaimardi and Potorous tridactylus. 2. Although protein content was consistently higher in bettong milk, lactational trends in both species are similar to those reported for other marsupials. 3. The faster relative growth rate of the bettong may be correlated with the increased protein and a higher milk intake.

Animals↗

PubMed1988

Changes in milk composition during lactation in the potoroo, Potorous tridactylus (Marsupialia: Potoroinae).

Milk samples from captive potoroos were analysed for composition during weeks 3-25 of the lactation period. During pouch residence, up to week 16, carbohydrate levels were high, ranging from 9 g 100 ml-1 at week 5 to 15 g 100 ml-1 at week 15; fat levels were consistently low, at around 2 g 100 ml-1; protein levels gradually increased from 5 g 100 ml-1 before week 10 to 12 g 100 ml-1 at week 16. Growth rates during this period increased exponentially, from 1 g week-1 at week 3 to 40 g week-1 at week 16. Thereafter, as the young left the pouch, marked changes were seen in carbohydrate and fat levels: by week 25, carbohydrate levels had fallen to 2 g 100 ml-1, and fat levels had risen to 26 g 100 ml-1. Protein levels increased moderately, reaching 15 g 100 ml-1 by week 25. Growth rates further increased during this period, to reach 60 g week-1 by week 25. Thus, trends in milk composition previously observed in Macropus species were observed also in the potoroo, suggesting a consistent pattern across the macropodid family. Carbohydrate levels in potoroo milk tend to be higher than in other macropodids, but total milk intake is as important as composition in determining growth rates.

Animals↗

PubMed1986

Growth and role of the corpus luteum throughout delayed gestation in the potoroo, Potorous tridactylus.

The growth cycle of the corpus luteum (CL) of the potoroo is similar to that of other macropodids. During delayed gestation, the post-partum CL remains quiescent until it is reactivated by removal of the sucking pouch young. The CL then undergoes a period of growth, rapid from Day 6 until Day 12, followed by a gradual decline from Day 21 to Day 27. Excision of the CL before Day 6 of pregnancy either inhibited embryonic development or failed to support it. Excision of the CL between 6 and 21 days after removal of pouch young did not prevent embryos developing to full term but interfered with parturition. Excision on Day 25 after removal of pouch young allowed birth but impaired lactation, neonates dying within 2 days. By Day 27, the CL appeared to be no longer essential for embryonic development, birth or neonate survival. It is suggested that the CL of the potoroo is required for a slightly greater proportion of pregnancy than in most larger kangaroos because the birth canal must be prepared before each parturition.

Animals↗

PubMed1985

Effect of cadmium on the reproductive organs of the male potoroo Potorous tridactylus (macropodidae).

Low (2.28 mg/kg) or high (4.56 mg/kg) doses of cadmium chloride were administered, either intraperitoneally or subcutaneously, to adult male potoroos (P. tridactylus). After 7 days, the testes, caput epididymis and spermatic cords of the high-dose groups all displayed a degree of cellular damage; however, the damage was not as extensive as that which occurs in some eutherian species after only 24 h. This time differential might be attributed to structural differences between the testicular blood supply in eutherians and marsupials.

Animals↗

PubMed1979

The oestrous cycle and basal body temperature in the common wombat (Vombatus ursinus).

An oestrous cycle length of 33 days (N = 4, range 32-34) was obtained for the common womab from a number of parameters including vaginal smears, vaginal biopsies, changes in pouch morphology and behavioral observation. All but one of the successive periods of oestrus occurred during winter. Hourly measurements of body temperature by telemetry showed a rhythm typical of nocturnal species. Superimposed on this diurnal rhythm was another rhythm whoch could be correlated with the oestrous cycle.

Animals↗

PubMed1973