ABSTRACT
Regeneration of mammalian digit tips is well described; however, associated cellular or molecular events have not been studied in humans. We describe an in vitro human fetal model of response to digit tip amputation, and report expression of the transcription repressor Msx1 in the developing and regrowing human digit tip. Human fetal digits from specimens ranging from 53 to 117 days' estimated gestational age (EGA) were cultured in a defined serum-free medium with supplemented oxygen for time periods from 4 days to 4 weeks. Histology and immunohistochemistry were performed on paired control and tip-amputated digits. Regrowing tissue covered the cut end of the distal phalanx in digits up to 80 days' EGA. Msx1 expression was detected beneath the nail field in control digits to at least 70 days' EGA and at the regrowing tip of 57-day digits at 4 and 7 days post-amputation. Our results show that human fetal digits regrow tissue in vitro in response to tip amputation. This process appears spatially associated with Msx1 expression. Msx1 expression appears increased at the regrowing tip of 57-day digits by 4 days after amputation.
Subject(s)
Amputation, Traumatic/metabolism , Amputation, Traumatic/physiopathology , Fingers/physiopathology , MSX1 Transcription Factor/metabolism , Regeneration/physiology , Fetus , Fingers/embryology , Gestational Age , Humans , Time Factors , Tissue Culture Techniques , Wound Healing/physiologyABSTRACT
It is demonstrated that isolated nuclei of sea urchin embryos are able to incorporate radioactive nucleotides into RNA.Some properties of the incorporation system are described.
ABSTRACT
Treatment of embryos of Paracentrotus lividus with a concentration of ZnSO4 which causes animalization, strongly inhibits the initiation of ribosomal RNA synthesis.The vegetalizing agent LiCl does not seem clearly to affect the synthesis of this RNA.
