title: Bone development in the fetus and neonate: role of the calciotropic hormones.
abstract: During embryonic and fetal development much of the skeleton initiates as a cartilaginous scaffold, which is progressively resorbed and replaced by bone. Endochondral bone formation continues until the growth plates fuse during puberty. At all life stages adequate delivery of mineral is required for the skeleton to achieve and maintain appropriate mineral content and strength. During fetal development the placenta actively transports calcium, phosphorus, and magnesium. Postnatally passive and then active absorption from the intestines becomes the main supply of minerals to the skeleton. Animal and human data indicate that fetal bone development requires parathyroid hormone (PTH) and PTH-related protein but not vitamin D/calcitriol, calcitonin, or (possibly) sex steroids. During the postnatal period, when intestinal calcium absorption becomes an active process, skeletal development begins to depend upon vitamin D/calcitriol but this requirement can be bypassed by increasing the calcium content of the diet or by administering intermittent calcium infusions.
authors: Medicine (Endocrinology and Metabolism), Obstetrics & Gynecology, and BioMedical Sciences, Faculty of Medicine, Memorial University of Newfoundland, Health Sciences Centre, 300 Prince Philip Drive, St. John's, Newfoundland, A1B 3V6, Canada. ckovacs@mun.ca
authors: Christopher S
authors: CS
authors: Kovacs
mesh_terms: D000818:Animals; D000831:Animals, Newborn / Q000502:physiology*; D001846:Bone Development / Q000502:physiology*; D002117:Calcitriol / Q000502:physiology; D005333:Fetus / Q000502:physiology*; D006801:Humans; D007231:Infant, Newborn / Q000502:physiology*; D010281:Parathyroid Hormone / Q000502:physiology; D044162:Parathyroid Hormone-Related Protein / Q000502:physiology; D014807:Vitamin D / Q000502:physiology
chemical_list: D010281:Parathyroid Hormone; D044162:Parathyroid Hormone-Related Protein; D014807:Vitamin D; D002117:Calcitriol