{'fraction_non_alphanumeric': 0.02476780185758514, 'fraction_numerical': 0.01671826625386997, 'mean_word_length': 4.855072463768116, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
[Formation and differentiation of facial mesenchyme in cultured rat embryos].

The purpose of this study is to clarify the development of the mammalian facial mesenchyme using the rat whole-embryo culture system. To examine the formation of the mesenchyme of the facial processes, a piece of millipore filter membrane was interposed between the prosencephalon and mesencephalon. When the filter was insetted at the 13-somite stage, the mesenchymal cell mass was observed at the mesencephalic side of the filter and so the facial process-formation of these embryos was poor at the 40-somite stage. However, the facial processes were normally formed when the filter was insetted at the 20-somite stage or put into the other cranial regions. These results show that the cells migrating in the mesencephalic region at the 13-somite stage form the facial mesenchyme in the cultured rat embryos. To detect the embryonic stage of differentiation of the facial mesenchyme, the effects of retinol and cartilage-derived factor (CDF) were examined. The 3H-thymidine incorporation by the mesenchymal cells of the facial processes was not decreased at 36, 40 and 42-somite stage by the addition of 10 μg/ml of retinol. However, it declined to 23.0% of the control value at the 50-somite stage. Twenty μg/ml of CDF stimulated the 3H-thymidine incorporation, especially after the 42-somite stage. These findings suggest that the alteration of the facial mesenchymal cells toward the retinol-sensitive cells is in progress at around the 42-somite stage and this alteration might be related to the differentiation into chondrocytes.