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Skeletal alterations in hypophysectomized rats: II. A histomorphometric study on tibial cortical bone
1Department of Medicine, Winthrop-University Hospital, Mineola, New York, USA.
The Anatomical Record
|April 1, 1995
Summary
Hypophysectomy significantly reduced bone formation and growth in young rats, leading to lower tibial bone mass. This indicates suppressed modeling-dependent bone formation without significant bone loss.
Area of Science:
- Endocrinology
- Bone Biology
- Skeletal Physiology
Background:
- Pituitary hormones are crucial for bone growth, modeling, and remodeling.
- Hypophysectomy (HX) removes pituitary hormone influence, impacting skeletal development.
Purpose of the Study:
- To investigate the effects of hypophysectomy (HX) on tibial cortical bone characteristics.
- To analyze changes in bone histomorphometry following HX in young rats.
Main Methods:
- Forty-five female Sprague-Dawley rats underwent hypophysectomy or served as controls.
- Tibial shaft cortical bone histomorphometry was performed at 0, 2, and 5 weeks post-surgery.
- Dynamic histomorphometry assessed bone formation and resorption parameters.
Main Results:
- Hypophysectomy significantly reduced tibial diaphysis dry weight, density, and cortical bone area compared to intact controls.
- Bone formation parameters (labeled surface, mineral apposition rate, bone formation rate) were profoundly decreased on both periosteal and endocortical surfaces.
- Eroded surface on the endocortical surface was greater in HX rats, though medullar size remained unchanged.
Conclusions:
- Hypophysectomy suppressed radial growth-dependent bone gain in young rats.
- The observed skeletal changes are linked to decreased modeling-dependent bone formation.
- Increased endocortical erosion did not impact marrow size post-hypophysectomy.