A Histochemical and Fine Structural Study of Extracellular Fibrils in the Developing Chick Embryo
Date of Award
Master of Arts (MA)
The histochemistry of developing connective tissues and its relation to early connective tissue fibrils was investigated in the chick embryo. An area well suited to correlated histochemical and electron microscopic study occurs around the notochord. Here early microfibrils later contribute to the cartilaginous model of the future vertebral body. Chick embryos were sacrificed at one, two, three, four, six and ten days of incubation and were prepared routinely for both light and electron microscopy. A series of five histochemical stains (PAS, alcian blue, Hale colloidal iron, metachromatic toluidine blue, methenamine silver) and two histological techniques (Mallory's connective tissue; Weigert's elastin) was used for the light microscopic demonstration of polysaccharides, mucoproteins, mucopolysaccharides and mature connective tissue elements.
The first positive response for all histochemical stains occurs on the third day of incubation. Moderate microfibrillar growth in electron microscopy precedes this by one day. At this time light microscopic staining patterns differ from electron microscopic fibrillar arrangements. By the sixth day, dense microfibrillar concentrations appear in the precartilage area where acid mucopolysaccharides are intensely concentrated. Staining for mature connective tissue fibrils does not occur until the tenth day.
Polysaccharides, mucoproteins and mucopolysaccharides are interfibrillar components that are closely associated with the early stages of fibrillogenesis. Microfibrils become intensely concentrated in a matrix of these substances. Here, the future cartilaginous model with its heavy population of unit collagen fibrils will form.
O'Connell, James J., "A Histochemical and Fine Structural Study of Extracellular Fibrils in the Developing Chick Embryo" (1969). Theses and Dissertations. 3685.