ULTRASTRUCTURAL-STUDY OF IMPLANTATION IN GOLDEN-HAMSTER .2. TROPHOBLASTIC INVASION AND REMOVAL OF UTERINE EPITHELIUM

  • 1 January 1976
    • journal article
    • research article
    • Vol. 122  (NOV) , 211-230
Abstract
Implantation sites (66) from 18 golden hamsters were examined by light microscopy and EM 4-5 1/2 days of pregnancy (post-ovulation). At 4 days some blastocysts began to invade the uterine epithelium, with trophoblastic processes penetrating and engulfing portions of the uterine epithelium. The majority of epithelial cells appeared normal before invasion, although at 2 implantation sites 3 or 4 adjoining epithelial cells were necrotic before penetration by the trophoblast. The epithelial cells were degenerating at the time the trophoblast invaded the epithelium. Inclusions, representing portions of the engulfed epithelium, and varying in size and electron density, were present throughout the invading trophoblast cells. At 5 1/2 days the uterine epithelium had disappeared and the embryo was now almost completely surrounded by blood lacunae.