1) General Zoological Data
The Dorcas gazelle (dorcas [Greek=gazelle]) is a North African, desert-dwelling gazelle. Several (perhaps as many as nine) subspecies have been described, many of which are severely endangered. Several breeding colonies exist in zoological parks.
There are numerous species of the Gazellini with a wide variety of coat color and differences in size. They are fully discussed by Nowak in 1999. The animals depicted here are "Saharan Dorcas gazelles". Many, but not all, African gazelles possess a characteristic chromosomal translocation (fusion) of an autosome with the X chromosome. Since the autosome is the same in all these gazelle species, it is conjectured that a common ancestor first had this complex karyotype and that it was the founding species of a large number of African gazelle species.
|Adult male "Saharan" Dorcas gazelle at the San Diego Zoo.|
|Adult Dorcas gazelles at the San Diego Zoo.|
|Group of Dorcas gazelles at the San Diego Zoo.|
General Gestational Data
The length of gestation has been cited as 164-174 days (Dittrich, 1970; Slaughter, 1971; Puschmann, 1989, Kranz et al., 1984). Newborns weigh between 1 and 1.8 kg, sexual maturity occurs at 1 year and 9 months. Single births are the rule; twins are uncommon (Jope, 1908; Dittrich, 1970; Kranz et al., 1984). We have encountered a conjoined stillborn twin fetas. Thus, some of the twins may be monozygotic. The male fetus that was associated with the first placenta depicted here, weighed 1,650 g. Adults weigh ca. 15 kg, longevity is over 17 years. There is little sexual dimorphism. Many additional reproductive data were summarized by Hayssen et al. (1993), and also by Kranz et al. (1984). Baharav (1983) compared the reproduction of the mountain gazelle (Gazella g. gazella) with that of the Dorcas gazelle. Both delivered young in March; first conception occurred at age 18 months, singletons were the rule. Dittrich (1970) stated that sexual maturity is reached at 27 months and that placentophagy is normal.
General Characterization of the Placent
|Term placenta of Dorcas gazelle. The left one-half is the maternal surface; the right one-half is the fetal surface.|
New Dorcas gazelle placenta of term infant.
Additional placenta of malformed term stillborn infant.
villi are folded and moderately branched. Unfortunately, both placentas
examined have had a moderate amount of autolysis, which is reflected in
the histologic appearance. No other specimens have been described.
Details of fetal/maternal barrier
|Fetal surface of a term Dorcas gazelle placenta with edematous-appearing villi. This is secondary to some autolysis.|
|Surface of a villus with binucleate trophoblastic cell at arrow.|
|Implantation site of term Dorcas gazelle placenta. This is near the edge of the cotyledon and show endometrial glands beneath the maternal blood vessels. The connective tissue of the endometrium is seen to interdigitate with the villi.|
|Chorionic membrane between cotyledons. Note the prominent trophoblast beneath the vascular chorionic plate.|
Trophoblast external to barrier
Other remarks - What additional Information is needed?
Dittrich, L.: Beitrag zur Fortpflanzungsbiologie afrikanischer Antilopen im zoologischen Garten. Zool. Garten 39:16-40, 1970.
Effron, M., Bogart, M.H., Kumamoto, A.T. and Benirschke, K.: Chromosome studies in the mammalian subfamily Antilopinae. Genetica 46:419-444, 1976.
L.A.: Pathology of Zoo Animals. Zoological Society of San Diego. San Diego,
Hayssen, V., van Tienhoven, A. and van Tienhoven, A.: Asdell's Patterns of Mammalian Reproduction: a Compendium of Species-specific Data. Comstock/Cornell University Press, Ithaca, 1993.
Jope, M.: Meine Erfahrungen in der Aufzucht von Dorcasgazellen und Axis-und Schweinshirschen. D. Zool. Garten 49:374-376, 1908.
Kranz, K.R., Xanten, W.A. and Lumpkin, S.: Breeding history of the Dorcas gazelles Gazella dorcas at the National Zoological Park, 1961-1981. Int. Zoo Yearb. 23:195-203, 1984.
Nowak, R.M.: Walker's Mammals of the World. 6th ed. The Johns Hopkins Press, Baltimore, 1999.
Puschmann, W.: Zootierhaltung. Vol. 2, Säugetiere. VEB Deutscher Landwirtschaftsverlag Berlin, 1989.
Ralls, K., Brugger, K. and Glick, A.: Deleterious effects of inbreeding in a herd of captive Dorcas gazelle Gazella dorcas. Int. Zoo Yearb. 20:137-146, 1980
Slaugther, L.: Gestation period of the Dorcas gazelle. J. Mammal. 52:480-481, 1971.
Wahrman, J., Richler, C., Goitein, R., Horowitz, A. and Mendelssohn, H.: Multiple sex chromosome evolution, hybridization and differential X chromosome inactivation in gazelles. In: Jerusalem Chromosome Conference, and Chromosomes Today 42:434-435, 1973.
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