28 



HUMAN PHYSIOLOGY 



another, become separated, remaining attached by elongated 

 processes. Between the cells, a clear, transparent, viscous 

 mucin-like substance makes its appearance, forming a soft 

 jelly-like tissue. This tissue is widely distributed in the 

 embryo as a precursor of the connective tissues, and after 

 birth it is still to be seen in the pulp of a developing tooth 

 and in the vitreous humour of the eye (Fig. 7). 



FlO. 7. Mucoid Tissue from an embryo rabbit. 



2. Fibrous Tissue. As development advances, the cells of 



mucoid tissue elongate 

 and become spindle- 

 shaped, and are continued 

 at their ends into fibres 

 (Fig. 8). These cells are 

 often called fibroblaats. 

 The connective tissues are 

 thus clearly distinguished 

 from the epithelia byhav- 



Fio.S.-Fibroblasts from young fibrous - the f orme( i material 



tissue. , 



between and not in the 



cells. They are composed of the following parts : 

 I. Formed material. 

 (a) Fibres. 

 (6) Matrix. 



II. Spaces (Connective Tissue Spaces). 

 III. Cells. 



