[Induced cleft palat by Retinoic acid through altering the cell proliferation and apoptosis at the key stages of palatal development].

To investigate the effects of retinoic acid (RA) on the proliferation and apoptosis of mesenchyme and epithelium at the key stages of palatal development, and to determine the embryonic alterations associated with cleft palate.

100 pregnant C57 females (E12) were equally divided into two groups. The experimental group was administered RA once (70 mg/kg) while the control group was administered corn oil only, and the heads of the embryos at E13.5-17.5 were collected and processed to paraffin. Sections were stained with hematoxylin and eosin for the morphological assessment of anterior,posterior, left and right palate, and BrdU and TUNEL assays for the detection of proliferation and survival of palatal mesenchyme and epithelium.

Simple treatment of RA at 70 mg/kg caused an incidence of 100％ cleft palate. During E13.5-15.5,cell proliferation was significantly promoted on the anterior palatal mesenchyme in the RA group, while no difference for the posterior palatal mesenchyme. Besides, the cell proliferation on anterior and posterior epithelium was comparable between the control and RA group. Less apoptotic cells were observed on epithelium during El3.5-14.5 in the RA group.

RA induces excessive cell proliferation of palatal mesenchyme, causing abnormal vertical palatal growth and failure of palatal shelves contact and fusion, which finally lead to cleft palate. RA also increases epithelium apoptosis.