|Red River Hog at San Diego Zoo.|
|Red River Hogs at San Diego Zoo.|
Most of the data pertaining to the red river hog have been detailed above. Thriving colonies of red river hogs are now being maintained in the San Diego Zoo and in some other institutions, with very good reproductive success. In contrast, the other species of bushpig, Potamochoerus porcus larvatus, is rarely represented in zoos and we know of no further studies on them.
|Pair of "bushpigs" (Potamochoerus porcus larvatus) at San Diego Zoo.|
2) General gestational data
Reproduction is poorly studied in this species, but Kingdon (1979) referred to a gestational length of 4 months, with 10 piglets being the maximum. In our facilities, twins and triplets have been the commonest numbers.
of the similarity of placentation to other Suidae (especially the domestic
pig), this is the only species of Suidae discussed in this book.
General characteristic of placenta
|Delivered twin placenta of a mature red river hog twin gestation. Note the degenerated ends of the sacs.|
|Thin villous placenta at left shows the congested fetal capillaries that come from the chorionic surface at the right. The surface epithelium is allantoic.|
|At the higher magnification of the villous surface, the simple cuboidal/cylindrical trophoblastic epithelium with faint brush borders is evident. Distended fetal capillaries are located directly below the trophoblast.|
5) Details of barrier structure
This is a typical epitheliochorial placenta without invasion of the uterus. The endometrial epithelium lies directly next to and interdigitates with the trophoblastic surface.
|These are sections of the implanted placenta from a domestic pig whose microscopic features are essentially identical to those of the red river hog.|
|At left is the uterine epithelium that interdigitates with the villous trophoblast-covered villi on the right.|
6) Umbilical cord
The specimens available to me had no umbilical cords. MacDonald and Bosma (1985), however, found that all suids possess two arteries and one vein in their cords, in addition to the allantoic duct. Naaktgeboren & Zwillingberg (1961) found no projections ("pearls", etc.) on the surface of cord or on the amnion of pigs, while it was common in most other artiodactyla.
|The fetal surface is slimy and gelatinous.|
9) Trophoblast external to barrier
There is no uterine invasion by trophoblast at all.
Other features of interest
Bosma, AA., deHaan, N.A. and MacDonald, A.A.: The current status of cytogenetics of the Suidae: A review. Bongo 18:258-272, 1991.
Eckstein, P. and Zuckerman, S.: The oestrus cycle in the mammalia. Chapter 4 (pp. 226-397), in Marshall's Physiology of Reproduction, 3rd ed. A.S. Parkes, Ed. Longmans, Green and Co., London, 1956.
Geisert, R.D.: Pigs. Pp. 792-799 in Vol. III of, Encyclopedia of Reproduction, E. Knobil and J.D. Neill, eds., Academic Press, San Diego, 1998.
Grubb, P.: The Afrotropical Suids Phaecochorus, Hylochchoerus, and Potamochoerus. Chapter 4, pp. 66-75, In, Pigs, Peccaries and Hippos. IUCN, Gland, Switzerland, 1993.
Heuser, C.H.: A study of the implantation of the ovum of the pig from the stage of the bilaminar blastocyst to the completion of the fetal membranes. Contrib. Embyol. Carnegie Inst. 19:229-243, 1927.
Kingdon, J.: East African Mammals. Vol. III, part B (Large Mammals). Academic Press, N.Y. 1979.
Leister, C.W.: The wild pigs of the world. Bull. N.Y. Zool. Soc. 42:121-130, 1939.
MacDonald, A.A.: Uterine vasculature of the pregnant pig: A scanning electron microscope study. Anat. Rec. 184:689-698, 1976.
MacDonald, A.A. and Bosma, A.A.: Notes on placentation of Suina. Placenta 6:83-92, 1985).
Marczynska, B. and Pigon, H.: Somatic chromosomes of the native African pig. Cytologia 38:111-116, 1973.
Melander, Y. and Hansen-Melander, E.: Chromosome studies in African wild pigs (Suidae, Mammalia). Hereditas 92:283-289, 1980.
Naaktgeboren, C. and Zwillingberg, H.H.L.: Untersuchungen über die Auswüchse am Amnion und an der Nabelschnur bei Walen, und Huftieren, mit besonderer Berücksichtigung des europäischen Hausrindes. Acta Morphol. Neerl.-Scand. 4:31-60- 1961.
Nowak, R.M. and Paradiso, J.L.: Walker's Mammals of the World. 4th ed. Vol. II. Johns Hopkins University Press, 1983.
Patten, B.M.: The Embryology of the Pig. 2nd ed. The Blakiston Co. Philadelphia, 1931 (reprinted 1947).
Puschmann, W.: Zootierhaltung.Vol. 2 Säugetiere. Deutscher Landwirtschaftsverlag, Berlin, 1989.
Ramsey, E. M.: The Placenta. Human and Animal. Praeger, N.Y., 1982.
Smith, H.A., Jones, T.C. and Hunt, R.D.: Veterinary Pathology. Lea and Febiger, Philadelphia, 1972.
Thenius, E.: Zur Evolution und Verbreitungsgeschichte der Suidae (Artiodactyla, Mammalia). Z. Säugetierk. 35:321-342, 1970.
Vercammen, P., Seydack, A.H.W. and Oliver, W.L.R.: The bush pigs (Potamochoerus porcus and P. larvatus). Pp. 93-101, In, Pigs, Peccaries and Hippos. IUCN, Gland, Switzerland, 1993.
Watanabe, T., Hayashi, Y., Ogasawara, N. and Tomoita, T.: Polymorphism of mitochondrial DNA in pigs based on restriction endonuclease cleavage patterns. Biochem. Genet. 23:105-113, 1985.
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