1) General Zoological Data
Despite the fact that gerenuks have an unique and well-known appearance, relatively little is known about the biology of these beautiful animals. A comprehensive book by Schomber (1966) provides all of the information available. There is no fossil record of precursors. The East African animals form a discontinuous range, with the smaller habitat in Tanzania, the majority further north, Kenya, Somalia, etc. Whether they extended at one time to Egypt seems to have been documented by drawings from many thousand years ago. The name Gerenuk stems from the Somali garanug meaning long-necked gazelle (Gotch, 1979). Lithos is Greek for stone, and kranion the skull - "stone skull". The posterior portions of the skull are said to be very hard. It is the only species in this genus, mostly inhabiting Somalia and surrounding counties. Two subspecies have been considered: L. w. walleri and L. w. sclateri, animals that have minor skeletal differences. The German "Giraffengazelle" well describes the extraordinarily long neck of these animals that are prone to become even longer when they graze on trees by standing on their hind legs. Horns are found in males only. Jones (1993) found the longevity to be 11+ years, while Crandall (1965) reported only 6+ years. Relatively few zoos have gerenuks, but they have reproduced well in most zoological gardens that have held them. Their number in Africa has been reduced drastically.
General Gestational Data
Leuthold (1978) described the social organization and behavior of gerenuks. His estimate of the length of gestation was 6.5-7 months. Single young are born that weigh around 3 kg (Puschmann, 1989). Schomber (1963, 1966) reported a 203 day length of gestation from observations in zoological gardens.
Details of fetal/maternal barrier
The villous epithelium consists of a single layer of trophoblast with numerous binucleate cells that are primarily located at the villous tips. Beneath the chorion, the trophoblast is more cylindrical and has a moderate amount of yellow pigmentation. The endometrial epithelium if flat and directly apposed to the trophoblast.
The umbilical cord of this gestation was 5 cm long, had no spirals and had numerous squamous plaques on its surface. There were a central allantoic duct, four large blood vessels and numerous small vessels, especially concentrated around the duct. That of a term gestation was 15 cm long.
This has not been described and, by the appearance of this uterus, it follows the general architecture of the ungulate uterine circulations.
Trophoblast external to barrier
There is no evidence of trophoblast infiltration of the uterus other than the surface of the fibrous-appearing superficial endometrium.
There is no subplacenta.
I know of no studies of the gerenuk immune system other than the identification of Trypanosome brucei antibodies in gerenuks by Black et al. (1999). Backues et al. (1999) vaccinated many species, including the gerenuk, with a genetically engineered Mengo virus.
18) Other remarks - What additional Information is needed?
Black, S.J., Wang, Q., Makadzange, T., Li, Y.L., van Praagh, A., Loomis, M. and Seed, J.R.: Anti-Trypanosoma brucei activity of nonprimate zoo sera. J. Parasitol. 85:48-53, 1999.
Clemens, E.T. and Maloiy, G.M.: Digestive physiology of East African wild ruminants. Comp. Biochem. Physiol. A 76:319-333, 1983.
Clemens, E.T. and Moloiy, G.M.: Colonic absorption and secretion of fluids, electrolytes and organic acids in East African wild ruminants. Comp. Biochem. Physiol. A 77:51-56, 1984.
Crandall, L.S.: Record of African antelopes in the New York Zoological Park. Int. Zoo Yearb. 5:52-55, 1965.
Gotch, A.F.: Mammals - Their Latin Names Explained. Blandford Press, Poole, Dorset, 1979.
Griner, L.A.: Pathology of Zoo Animals. Zoological Society of San Diego, San Diego, California, 1983.
Jones, M.L.: Longevity of ungulates in captivity. Intern. Zoo Yearbk. 32:159-169, 1993.
W.: On social organization and behaviour of the gerenuk Litocranius
walleri (Brooke 1878). Z. Tierpsychol. 47:194-216, 1978.
Schomber, H.W.: Beiträge zur Kenntnis der Giraffengazelle (Litocranius walleri Brooke, 1978) Säugetier. Mitt. 11:1-44, 1963.
Schomber, H.W.: Giraffengazelle und Lamagazelle. Die Neue Brehm-Bücherei. A. Ziemsen, Wittenberg, 1966.
Wasser, S.K., Hunt, K.E., Brown, J.L., Cooper, K., Crockett, C.M., Bechert, U., Millspaugh, J.J., Larson, S. and Monfort, S.L.: A generalized fecal glucocorticoid assay for use in a diverse array of nondomestic mammalian and avian species. Gen. Comp. Endocrinol. 120:260-275, 2000.
Wurster, D.H. and Benirschke, K.: Chromosome studies in the superfamily Bovoide. Chromosoma 25:152-171, 1968.
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