Catch-up growth induced by growth hormone in the craniofacial skeleton of the Snell strain of the hypopituitary dwarf mouse.

Immature Snell strain dwarf mice were treated with human growth hormone for 20 and 40 days, between the ages of 22 and 41 days and 22 and 61 days, respectively. Mature dwarfs were similarly treated for 20 and 40 days between the ages of 62 and 81 days and 62 and 101 days, respectively. These groups of treated mice were compared with untreated dwarfs and normal mice reared under the same conditions. The catch-up growth effected by human growth hormone on the craniofacial and somatic development of the Snell strain dwarf mouse at both immature and mature ages was considerable, overall being approximately 14 per cent. Neurocranial parameters tended toward the values of normal mice achieving 89-98 per cent of normal growth. Viscerocranial parameters showed greater catch-up, from a lower start point, reaching 81-93 per cent of the control. This catch-up in mature mice (aged 82-102 days) was at a time when any substantial growth in either dwarf or normal mice has usually ceased.