Get access

Placental specializations of the mountain spiny lizard Sceloporus jarrovi

Authors

  • Daniel G. Blackburn,

    Corresponding author
    1. Department of Biology and Electron Microscopy Facility, Trinity College, Hartford, Connecticut 06106
    • Department of Biology, Trinity College, Hartford, CT 06106
    Search for more papers by this author
  • Gregory S. Gavelis,

    1. Department of Biology and Electron Microscopy Facility, Trinity College, Hartford, Connecticut 06106
    Current affiliation:
    1. Oregon Institute of Marine Biology, University of Oregon, 63466 Boat Basin Road, Charleston OR 97420
    Search for more papers by this author
  • Kristie E. Anderson,

    1. Department of Biology and Electron Microscopy Facility, Trinity College, Hartford, Connecticut 06106
    Search for more papers by this author
  • Amy R. Johnson,

    1. Department of Biology and Electron Microscopy Facility, Trinity College, Hartford, Connecticut 06106
    Current affiliation:
    1. University of Chicago Hospitals, Department of Medicine, 5841 S. Maryland Ave, Chicago, IL 60637
    Search for more papers by this author
  • Kent D. Dunlap

    1. Department of Biology and Electron Microscopy Facility, Trinity College, Hartford, Connecticut 06106
    Search for more papers by this author

Abstract

The lizard Sceloporus jarrovi (Phrynosomatidae) is one of the most widely studied viviparous reptiles of North America. Past research has assumed that placentation in this species is relatively simple and functions mainly in gas exchange. Our examination of the late stage placenta via transmission electron microscopy reveals that S. jarrovi has a unique combination of placental characteristics, with unusual specializations for secretion and absorption. In the chorioallantoic placenta, chorionic and uterine tissues are directly apposed through eggshell loss, and their epithelia are greatly attenuated, enhancing gas exchange; this placenta shows evidence of both nutrient transfer and endocrine function. Contrary to past inferences, a yolk sac placenta forms from the avascular omphalopleure and persists through the end of gestation. The uterine epithelium is enlarged and secretory, and the fetal omphalopleure shows branching absorptive channels and other specializations for uptake. Elsewhere, the omphalopleure develops elongated folds that protrude into a coagulum of degenerating shell membrane and other organic material. Uterine tissue in this region shows specializations for absorption. Placental features in S. jarrovi have unexpected functional implications, and challenge assumptions that specializations for nutrient transfer are confined to matrotrophic species. J. Morphol. 271:1153–1175, 2010. © 2010 Wiley-Liss, Inc.

Get access to the full text of this article

Ancillary