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Journal of Experimental Biology, Vol 174, Issue 1 97-108, Copyright © 1993 by Company of Biologists

JOURNAL ARTICLES

A NOVEL PATTERN OF EMBRYONIC NUTRITION IN A VIVIPAROUS REPTILE

J. R. Stewart and M. B. Thompson

Vitellogenesis and placental transfer both contribute substantially to embryonic nutrition in the viviparous scincid lizard Pseudemoia entrecasteauxii. Neonatal wet mass was 396 % greater than egg wet mass and neonatal dry mass was 168 % greater than egg dry mass. We estimate that 49 % of the organic molecules for embryonic growth and metabolism were provided by placental nourishment. This pattern of embryonic nutrition, in which ovarian and uterine contributions are approximately equivalent, has not been reported previously for reptiles. Female Bassiana duperreyi, a closely related oviparous species, produced larger clutches of larger eggs. Although there was a great disparity in egg mass between these two species, differences in newborn composition were less pronounced. Mean dry mass, adjusted for female size, of B. duperreyi eggs was 135 % greater than mean dry mass of P. entrecasteauxii eggs, yet mean dry mass of B. duperreyi offspring was only 21 % greater than that of P. entrecasteauxii offspring. Embryonic gains in water and inorganic salts during gestation in P. entrecasteauxii were substantial and resulted in the production of neonates that contained greater quantities of these variables compared to offspring of B. duperreyi. These data confirm Weekes' hypothesis that P. entrecasteauxii is matrotrophic and support her hypothesis that this species has undergone evolutionary reduction in yolk quantity.


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M. Thompson, B. Speake, J. Stewart, K. Russell, R. McCartney, and P. Surai
Placental nutrition in the viviparous lizard Niveoscincus metallicus: the influence of placental type
J. Exp. Biol., January 11, 1999; 202(21): 2985 - 2992.
[Abstract] [PDF]


© The Company of Biologists Ltd 1993