Sites of Action of Growth Hormone in Cartilage

Abstract

Since the isolation of growth hormone many of its actions on the total organism have been widely investigated and well recognized. The present report describes an attempt to locate the cells, within the cartilage of the upper tibial epiphysis, which respond to the stimulus of growth hormone. With the aid of tritiated thymidine (both in vitro and in vivo), colchicine and the electron micro-6. Trowell, C.

Activity of human growth hormone and related polypeptides on the adipose conversion of 3T3 cells.

“…The possibility should be borne in mind that the traditional assay for growth hormone, based on the increase in size of the epiphyseal cartilage, may depend in a similar way on the ability of the hormone to support differentiation of chondrocyte precursors. The inability of cultivated skeletal fragments to respond to growth hormone (29,31) is probably due to technical factors in the culture system and not, as had been believed previously, to an exclusively indirect mode of action of the hormone (17).…”

Mechanism of the Stimulatory Effect of Growth Hormone on Longitudinal Bone Growth*

“…The possibility that GH might regulate the rate of differentiation of prechondrocytes has only recently been recognized (32). Interestingly, more than 20 yr ago it was indeed suggested that GH stimulates longitudinal bone growth by stimulating cells in the germinal zone of the growth plate (28).…”

“…At this stage of development endochondral ossification occurs in both proximal and distal directions. Gradually, a laminar organization of chondrocytes in the plate with progessively more mature cells develops in the distal direction (26)(27)(28). After the development of the epiphyseal center of ossification, the epiphyseal growth plate is constrained between two calcified surfaces.…”

Cellular Heterogeneity and Insulin-Like Growth Factor I Immunoreactivity among Epiphysial Growth Plate Chondrocytes in the Pig

“…This IGF-I then interacts with chondrocytes, inducing proliferation by autocrine or paracrine mechanisms [Isaksson et al. 1987], The second hypothesis maintains that GH stimulates the local produc tion of IGF-I [Underwood etal.. 1986], Rigal [ 1964] demonstrated that chondrocytes of the ger minal zone are the targets of GH in the epiphysial growth plate. When GH and tritiated thymidine were injected into rabbits.…”