Original Paper

Mitotic Polyploidization in Trophoblast Giant Cells of the Alpaca
K. Klisch^a, E. Bevilacqua^b, L.V.M. Olivera<sup>c

a</sup>Microscopical Anatomy, Hannover Medical School, Hannover, Germany;
^bDepartment of Cell and Developmental Biology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil;

Address of Corresponding Author

Cells Tissues Organs 2005;181:103-108 (DOI: 10.1159/000091099)

  Key Words

• Genome multiplication
• Placenta
• Camelid

  Abstract

Genome multiplication is a typical feature of trophoblast giant cell (TGC) development in many species. Elevated nuclear DNA contents can be achieved by modified cell cycles with a complete lack of mitosis (endoreduplication) or with incomplete mitoses. The aim of this study is to characterize genome multiplication in the alpaca TGC. Placental tissues of gestation days 150, 264 and 347 (near term) and term placentae were processed for light microscopy and for transmission electron microscopy. Each TGC showed many nuclear profiles. Observation of serial sections revealed that TGCs are truly multinucleate with several highly lobulated nuclei. Feulgen staining showed that TGC nuclei have a higher DNA content than nuclei of other trophoblast cells. The number of argyrophilic nucleolar organizer regions (AgNORs) in nuclear profiles of TGC was between 15 and 100, while other trophoblast cells showed 1 or 2 AgNORs. Large multipolar mitotic figures with maximal diameters of 80 µm were observed in the alpaca placentas on gestation days 264 and 347. No cytokinesis was seen in TGC. The results show that the mode of genome multiplication in the alpaca TGC is mitotic polyploidization. Subsequent acytokinetic mitoses may lead to an accumulation of chromosomes and centrioles in TGC. With increasing ploidy levels, the shape of these polyploidizing mitoses becomes more irregular. The restitution of nuclei after these complex multipolar mitoses is likely to result in the irregular nuclear shape in TGC.

Copyright © 2005 S. Karger AG, Basel

  Author Contacts

Dr. Karl Klisch
Microscopical Anatomy, OE 4110, Hannover Medical School
Carl Neuberg Strasse 1
DE-30625 Hannover (Germany)
Tel. +49 511 532 2877, Fax +49 511 532 2889, E-Mail klisch.karl@mh-hannover.de

  Article Information

Accepted after revision: November 24, 2005
Published online: July 04, 2008
Number of Print Pages : 6
Number of Figures : 3, Number of Tables : 0, Number of References : 22