تکامل جنینی کام سخت در موش صحرائی

ABSTRACT: In order to study the development of the hard palate, 31 rat embryos were sacrified at daily intervals from 13 to 19 days of gestation .Embryos' heads were sectioned serially and stained with H.E, trichrome masson's paraldehyde fuchsin. SEIT The results were as follow: 1- The palatal shelves were observed in the medial side of the maxillary processes as two bulged prominence on 13 days of gestation . 2-Those two palatal shelves were in vertical position on 14-15 th days of gestation. Epithelial thickness was homogeneous on either side of the shelves and showed continuous membrane.I door 3- Invasion of vascular mesenchymal tissue was prominent in relation to the mechanism of palatal shelves elevation ,but there was no evidence of elastic fiber and smooth muscles. 4- On 16 th day of gestation, epithelial thickness of palatal shelves was thinner and basement membrane at the side of two palatal fusion was interrupted . There was no evidence of epithelial dead cell in fusion zone.