Since this species is so similar to domestic goats, no other Capra species will be presented in these pages.
Nowak (1999) stated that domestication of goats began about 8,000 years ago, with C. aegagrus being the ancestral species. More recently, Luikart et al. (2001), using mtDNA studies, estimated divergence taking place about 10,000 years ago, but with three different lineages serving as the domestic goat ancestors.
General gestational data
|Cretan goat with her two young at San Diego Zoo.|
|Young male Cretan goat with "beard", at San Diego Zoo.|
|This is the placenta of a term pregnancy from a Cretan goat with a 1,425 g surviving neonate. It weighed 200 g and measured 68x35x0.3 cm. There were 65 cotyledons, with maximal dimension of 5x3 cm.|
|Second specimen of Cretan goat placenta with 48 cotyledons.|
|Cretan goat: 5/27/2002. S-4896|
|Concave cotyledons from experimental domestic goat placentas at same magnifications. Left 82 day, middle 105 days, right 122 days gestation (partial). Fetal surface is on top and the middle placenta is attached to the uterus below.|
|Cretan goat trophoblast of the intercotyledonary region with crystalline, pigmented inclusions. These crystalline proteins are commonly found in ruminant trophoblast.|
|Fetal surface of term Cretan goat placenta with amnion and fetal surface vessel at left, and villous structures at right.|
|Binucleate trophoblast of Cretan goat placenta|
|Cross-section through the allantoic duct of this placenta next to an umbilical artery. The duct is lined by thick urothelium and is accompanied by many small vessels.|
|Attachment of the membranes on a cotyledon (below) with the allantoic cavity at the top left, and amnion at top right. M=maternal endometrial tissue, intertwining with villi.|
|Amnion/allantois interface with allantoic vessels in between epithelia.|
The intercotyledonary membranes and their relation to the uterus have been best studied by Davies & Wimsatt (1966) who defined the regions of the so-called "areolae". These areas are located atop the orifices of endometrial glands and are presumed to be an important zone of nutritional transfer to the fetus. This is the site of "uterine milk" production by the endometrium. The remainder shows a close approximation of the microvillous surfaces of endometrial epithelium and cellular trophoblast. There is no decidua capsularis.
Trophoblast external to barrier
Other relevant features and additional needs for information
Anderson, T.D. and Cheville, N.F.: Ultrastructural morphometric analysis of Brucella abortus-infected trophoblasts in experimental placentitis. Amer. J. Pathol. 124:226-237, 1986.
Bautzmann, H. and Schröder, R.: Vergleichende Studien über Bau und Funktion des Amnions. Z. Zellforsch. 43:48-63, 1955.
Bunch, T.D., Foote, W.C. and Spillett, J.J.: Sheep-goat hybrid karyotypes. Theriogenology 6:379-385, 1976.
Cell cultures are available from CRES at: www.sandiegozoo.org/CRES
Davies, J. and Wimsatt, W.A.: Observations on the fine structure of the sheep placenta. Acta anat. 65:182-223, 1966.
Dent, J., McGovern, P.T. and Hancock, J.L.: Immunological implications of ultrastructural studies of goat x sheep hybrid placentae. Nature 231:115-117, 1971.
Gray, A.P.: Mammalian Hybrids. Second edition. A Check-List with Bibliography. Commonwealth Agricultural Bureaux, Farnham Royal, Slough, UK, 1972.
Kaufmann, P.: Vergleichend-anatomische und funktionelle Aspekte des Placenta-Baues. Funkt. Biol. Med. 2:71-79, 1983.
Keisler, D.H.: Sheep and Goats. In, Encyclopedia of Reproduction, Vol. 4, E. Knobil and J.D. Neill, eds. Academic Press, San Diego, pp. 479-492.
King, G.J., Atkinson, B.A. and Robertson, H.A.: Implantation and early placentation in domestic ungulates. J. Reprod. Fertil. Suppl. 31:17-30, 1982.
Naaktgeboren, C. and Zwillenberg, H.H.L.: Untersuchungen über die Auswüchse und an der Nabelschnur bei Walen und Huftieren, mit besonderer Berücksichtigung des europäischen Hausrindes. Acta Neerl.-Scand. 4:31-60, 1961.
Luikart, G., Gielly, L., Excoffier, L., Vigne, J.D., Bouvet, J. and Taberlet, P.: Multiple maternal origins and weak phylogeographic structure of goats. Proc, Natl. Acad. Sci. USA 98:5927-5932, 2001.
Makowski, E.L.: Maternal and fetal vascular nets in placentas of sheep and goats. Amer. J. Obstet. Gynecol. 100:283-288, 1068.
McGovern, P.T.: The effect of maternal immunity on the survival of sheep x goat hybrid embryos. J. Reprod. Fertil. 34:215-220, 1971.
Mossman, H.W.: Vertebrate Fetal Membranes. MacMillan, Houndmills, 1987.
Nowak, R.M.: Walker's Mammals of the World, Vol. II. The Johns Hopkins University Press, Baltimore, 1999.
Ross, M.G., Ervin, M.G., Rappaport, V.J., Youssef, A., Leake, R.D. and Fisher, D.A.: Ovine fetal urine contribution to amniotic and allantoic compartments. Biol. Neonat. 53:98-104, 1988.
Tucker, E.M., McGovern, P.T. and Hancock, J.L.: Serological investigations into the cause of death of goat x sheep hybrid fetuses. J. Reprod. Fertil. 27:417-425, 1971.
Wimsatt, W.A.: New histological observations on the placenta of the sheep. Amer. J. Anat. 87:391-458, 1950.
Wooding, F.B.P.: Role of binucleate cells in fetomaternal cell fusion at implantation in the sheep. Amer. J. Anat. 170:233-250, 1950.
F.B.P., Flint, A.P.F., Heap, R.B. and Hobbs, T.: Autoradiographic evidence
for migration and fusion of cells in the sheep placenta: Resolution of
a problem in placenta classification. Cell Biol. Internat. Reports 5:821-827,
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