C. G. Dacke, S. Arkle, D. J. Cook, I. M. Wormstone, S. Jones, M. Zaidi, Z. A. Bascal

Research output: Contribution to journalArticlepeer-review

184 Scopus citations


Medullary bone forms in egg-laying birds in response to gonadal steroids and is the most overtly oestrogen-dependent of all bone types. It acts as a labile reservoir for the supply of eggshell calcium. Previous studies indicate that feeding calcium- and vitamin-D-deficient diets to chickens results in resorption of cortical rather than medullary bone. More recent studies in calcium-stressed quail hens question this hypothesis and suggest that during the first 2 weeks of dietary calcium depletion the medullary bone is resorbed while cortical bone volume remains intact. The role of the osteoclast in bone resorption is the focus of much research that has recently included studies of medullary bone osteoclasts. The functional morphology of the avian cells, i.e. changes from quiescent to active osteoclasts with ruffled borders, reflects the rapid changes in medullary bone turnover that occur during the egg-laying cycle. Unlike mammalian osteoclasts, those from avian sources generally appear refractory to inhibitory factors such as calcitonin or raised extracellular calciumconcentration. However, medullary bone osteoclasts cultured in vitro for several days recover their ability to respond to the latter factor by increasing their levels of free cytosolic Ca2+, reducing tartrate-resistant acid phosphatase secretion and reducing their cell spread area. It is suggested that factors such as ambient calcium levels and prostaglandins may form part of a system of rapid local control for medullary bone osteoclast activity.

Original languageEnglish
Pages (from-to)63-88
Number of pages26
JournalJournal of Experimental Biology
Issue number1
StatePublished - Nov 1993
Externally publishedYes


  • bird
  • calcium
  • medullary bone


Dive into the research topics of 'MEDULLARY BONE AND AVIAN CALCIUM REGULATION'. Together they form a unique fingerprint.

Cite this