PRENATAL DEVELOPMENT OF THE SCAPULA OF RABBIT

Mahmoud M. Elgendy, Ahmed E. Rashwan, Ahmed G. Nomir, Ahmed I. Sayed-Ahmed and Ashraf A. El Sharaby*

ABSTRACT

In this study, we investigated the spatiotemporal patterns of the scapular development in rabbit embryos using light microscopic examination. Tissue sections were prepared from specimens collected at the embryonic day (E) 11, 14, 17, 21 and 28 days, and stained with hematoxylin and Eosin, Safranin-O, Periodic Acid-Schiff, von Kossa's stains and Fast green as well as double staining of Alcian blue with Alizarin Red. We observed the following characteristic chronological sequences: 1) At E11, the limb bud was formed of undifferentiated mesenchymal cells, marginal vein, apical ectodermal ridge and progress zone. 2) At E14, the scapular blade appeared as a condensation of mesenchymal cells differentiated into chondrocytes. 3) At E17, endochondral ossification was induced after the invasion of blood vessels and formation of three different types of chondrocytes arranged in morphologically distinct zones. 4) At E21, appearance of primary ossification center within the scapula. There were two primary ossification centers; one within the center of scapular blade and the second one in the scapular spines. Ossification extended bidirectionally in both sides and elongation of the scapula continuous until taken mostly the shape of the future scapula. 5) At E28, remodeling and resorption processes of scapula occurred due to a substantial increase in the number of osteoclast and osteocytes. We conclude that the prenatal pattern of scapular development is peculiar in rabbit, and that our results provide better understanding of bone growth in the flat bone and are useful for teratological and clinical studies of regeneration and healing of flat bone.

Keywords: Rabbit - Scapula - Development – Ossification.