HISTOLOGICAL ASPECTS OF THE MEDULLARY BONE CORRELATED TO DIFFERENT STAGES OF THE EGG FORMATION IN HENS

Abstract

The experiment was carried out on a batch formed by 10 laying hens, ISA Brown hybrid, at the first laying cycles, 50 weeks old, hold single in cages and fed with granulated forage. The hens were watched for 3 weeks in order to establish the moment of the oviposition and depending on that their slaughtering was set out so that the different stages of the egg formation could be observed. The hens were divided into 4 groups – I, II, III, IV- depending on the time elapsed from the last oviposition. Femur fragments have been drawn from the central zone of the diaphises and transformed in hematoxiline-eozine and alcian-blue stained preparations, the trichromic Mallory method and the Dorfmann-Epstein method for the emphasising of the alkaline phosphatasis. At the hens of the first group the presence of the medullary bone is shown and is characterised by an intense ossification process with compact bone structure, with well formed osseus trabeculae that occupy the medullar cavity. There is also present a rich content of acid mucopolyssacharide. The hens from the second group (II) have a well formed medullary bone, with visible osseus trabeculae. From the histological point of view, the medullary bone of the hens from the third group (III) is rarefied with large areolae, with collagen fibres that lack osein, having thus a characteristic aspect of massive decalcification. At the hens from the fourth group (IV) the medullary bone shows synthesis processes and bone matrix forming, positive, intensive FAL activity, that proves the presence of active osteoblasts, i.e. bone remodelling processes.

Keywords

• laying fowl
• medullary bone
• osteoclast
• osteoblast