Medullary bone of laying chickens

Abstract

EIGHT FIGURESThe clianges in the medullary bone of laying birds offer unusual opportunities for the study of several aspects of bone formation and destruction. Thus the rapid cyclic formation and breakdown of this bone in laying pigeons enabled Bloom, Bloom, and McLeaii ('41) to conclude that the various types of cells of bone are temporary functional states of the same cell. We have continued to study tlie medullary bone of laying birds and have tried to find out whether the cellular transformations are especially rapid in the chicken with her large clutches and extended periods of egg laying.

Medullary bone-like tissue in the mandibular symphyses of a pterosaur suggests non-reproductive significance

“…The composition of medullary bone is similar to that of cortical and cancellous trabecular bone; however, the proportional amount of components are different with medullary bone being more calcified, having higher apatite to collagen ratio, and containing more non-collagenous proteins, proteoglycans and carbohydrates in the matrix 7,12,14,15 . This bone tissue type was first described in pigeons 16 , and later in some other species of extant birds, among others in domestic fowl, Japanese quail, duck and ostrich 3,10,11,[17][18][19][20][21] . The amount, microanatomy and distribution of medullary bone can be different in different species of birds as well as in different phases of the reproductive cycle 1,11,17,21,22 .…”

“…This bone tissue type was first described in pigeons 16 , and later in some other species of extant birds, among others in domestic fowl, Japanese quail, duck and ostrich 3,10,11,[17][18][19][20][21] . The amount, microanatomy and distribution of medullary bone can be different in different species of birds as well as in different phases of the reproductive cycle 1,11,17,21,22 . Apart from the controversial results on mice forming medullary bone-like tissues in response to unnaturally high oestrogen doses 23,24 , medullary bone has not been reported in any extant non-avian amniotes 25,26 .…”

“…Growing from the endosteal layers inwards to the medullar cavity, and mostly being composed of woven bone 6 , medullary bone has no mechanical function but serves as a calcium storage that can be quickly mobilized during the calcification of the hard-shelled eggs of birds [6][7][8][9] . According to the phases of the egg-laying cycle, medullary bone can be characterized by rapid formation in the period of maturing follicles, and subsequent rapid destruction during the calcification of the eggshell [10][11][12] . This fast formation-resorption cycle of medullary bone corresponds well with its microanatomy as well as histology: (i) it has large surface areas due to its highly porous, vascularized nature; (ii) its trabeculae are composed of woven bone 6 ; (iii) the number and activity level of osteoclasts is considerably higher in medullary bone than in cortical bone 13 .…”

The effect of a bisphosphonate on bone volume and eggshell structure in the hen

“…The loss of these structural bone components leads to osteoporosis in laying hens and measurements of trabecular bone volume are used to assess the degree of bone loss (Wilson et al, 1992). Rapid sequential changes from medullary bone resorption to formation occur with each egg laying cycle (Bloom et al, 1958). Ultra-structural and light microscopy studies show that osteoid seams indicating bone formation and resorption lacunae indicating bone resorption, are present on medullary bone, but are very rarely found on trabecular bone (S. Wilson, manuscript in preparation) indicating minimal trabecular bone turnover.…”

A Histomorphometric, Structural, and Immunocytochemical Study of the Effects of Diet-induced Hypocalcemia on Bone in Growing Rats

“…1958; Stauffer et al 1973), and (d) in young, growing animals, the presence of severe calcification defects similar to those observed in rickets and osteomalacia (Bloom et al 1958;Stauffer et al 1973;de Bernard et al 1980;Pettifor et al 1984).…”