Connochaetes taurinus; C. gnou
1) General Zoological Data
Two species are recognized: the much more common brindled gnu (also white-bearded or blue gnu) and the smaller white-tailed gnu (black gnu). Connochaetes derives from konnos (Greek = beard) and khaite (flowing hair), while gnou is said to be Hottentot for the antelope (Gotch, 1979). The white-tailed gnu is now very rare and perhaps limited to areas of Namibia, while the blue wildebeest exists in larger regions of South and Southeast Africa and is well-known because of its large migrations. It is also much more common in zoological gardens, the former being very uncommonly seen now. Several subspecies have been described of the blue gnu that are mainly regional color variants. Adults weigh up to 275 kg, neonates weigh around 22 kg. Longevity is over 21 years (Jones, 1993).
Corbet & Robinson (1991) estimated the divergence time of these two species as 1 MYA from mtDNA studies. Arctander et al. (1999) studied mtDNA regions of three alcelaphine species (gnu, topi, hartebeest) and found them to be closely related. Moreover, they provided evidence that they had been much more widely distributed over Africa in the past.
General Gestational Data
Reproduction of wildebeest is highly seasonal in Africa. The length of gestation is 8-9 months (250-260 days) with single offspring weighing 20-22 kg. Age of first conception is about 28 months (Mentis, 1972). Placentas weigh between 1,500 and 1,800 g. Estes & Estes (1979) reviewed the social organization of wildebeest and make reference to the high neonatal survival among wildebeest calves in the Ngorongoro Park.
General Characterization of the Placenta
Details of fetal/maternal barrier
The barrier is epithelio-chorial and there is no infiltration of the uterus by trophoblast. Beneath the chorionic surface of at least one of the two mature placentas there was degeneration of the subchorionic tips of the maternal septa with some hemorrhage. A few of the cylindrical trophoblast beneath the chorion has incorporated yellow pigment. It was iron-staining negative. The villi are covered by a single layer of cuboidal trophoblast with a large number of binucleate cells, investigated in other ruminants by Wooding (1982) as well as by Atkinson et al. (1993). The latter produce glycoproteins and, most likely as in other ungulates, are responsible for the secretion of placental lactogen.
The umbilical cord contains 4 large blood vessels, an allantoic duct and a number of small blood vessels. Numerous foci of squamous metaplasia are found on the surface. Hradecky (1983) stated that the cord of these animals measures usually less than 20 cm.
No details have been published.
Trophoblast external to barrier
There are no special features worth noting. There is no subplacenta and there are no "metrial glands".
I am not aware of any immunological studies other than the search for antibodies to viruses.
Other remarks - What additional Information is needed?
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Estes, R.D. and Estes, R.K.: The birth and survival of wildebeest calves. Z. Tierpsychol. 50:45-95, 1979.
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Forsyth, I.A.: Variation among species in the endocrine control of mammary growth and function: the roles of Prolactin, growth hormone, and placental lactogen. J. Dairy Sci. 69:886-903, 1986.
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Griner, L.A.: Pathology of Zoo Animals. Zoological Society of San Diego, San Diego, California, 1983.
Grobler, J.P. and van der Bank, F.H.: Genetic variability in South African blue wildebeest (Connochaetes taurinus). Comp. Biochem. Physiol. B. 106:755-762, 1993.
Hradecky, P.: Uterine morphology in some African antelopes. J. Zoo Anim. Med. 13:132-136, 1982.
Hradecky, P.: Placental morphology in African antelopes and giraffes. Theriogenology 20:725-734, 1983.
Hradecky, P., Mossman, H.W. and Stott, G.G.: Comparative histology of antelope placentomes. Theriogenology 29:693-729, 1988.
T.C. and Benirschke, K.: An Atlas of Mammalian Chromosomes. Springer-Verlag,
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Kuttler, K.L.: Anaplasma infections in wild and domestic ruminants: a review. J. Wildl. Dis. 20:12-20, 1984.
Matthee, C.A. and Robinson, T.J.: Cytochrome b phylogeny of the family bovidae: resolution within the alcelaphine, antilopini, neotragini, and tragelaphini. Mol. Phylogenet. Evol. 12:31-46, 1999.
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Ralls, K., Brugger, K. and Ballou, J.: Inbreeding and juvenile mortality in small populations of ungulates. Science 206:1101-1103, 1979.
Rossiter, P.B., Jessett, D.M. and Karstad, L.: Role of wildebeest fetal membranes and fluids in the transmission of malignant catarrhal fever virus. Vet. Rec. 113:150-152, 1983.
Watson, P.F.: Electroejaculation, semen characteristics and semen preservation of the brindled gnu. J. Reprod. Fertil. 47:123-126, 1976.
Wooding, F.B.: The role of the binucleate cell in ruminant placental structure. J. Reprod. Fertil. Suppl. 31:31-39, 1982.
Wurster, D.H. and Benirschke, K.: Chromosome studies in the superfamily Bovoidea. Chromosoma 25:152-171, 1968.
Zukowsky, L.: Bastarde zwischen Weißschwanz- und Streifengnu. Zool. Garten 33:165-173, 1967.
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