F. Kristek et M. Gerova, DYNAMICS OF ENDOTHELIUM-MUSCLE CELL CONTACTS IN THE CORONARY-ARTERY OF THE DOG IN ONTOGENY, Acta anatomica, 158(3), 1997, pp. 166-171
The myo-endothelial area in the coronary artery conduit was described
in 3 developmental stages: in fetuses, newborns, and adult dogs. Trans
mission and scanning electron microscopy were used for the study, and
morphometry was used for quantitative evaluation. In all three stages,
the internal elastic lamina was found to be fenestrated. Endothelial
cells and smooth muscle cells (SMC) approached the fenestrae, and prot
rusions of one or both cells entered into the fenestrae. In some place
s contacts between endothelial and SMC were found. The patterns of mut
ual approaches of smooth muscle and endothelial cells, as well as the
entering into the fenestrae were similar in all three stages. The myoe
ndothelial contacts were counted per 100 mu m inner circumference of t
he coronary artery and the numbers observed, i.e. 5.17 +/- 0.50 in fet
uses, 1.94 +/- 0.17 in newborns and 0.33 +/- 0.09 in adult animals, pr
oved clearly that the frequency of myo-endothelial contacts, highest i
n fetuses, decreases with age. With regard to the dual control of the
coronary smooth muscle and/or diameter, it is noteworthy that an oppos
ite trend can be observed in the development of innervation of the cor
onary artery: the autonomic nerve fibres with varicosities are missing
in the coronary wall 1 week before birth, while after birth their num
ber keeps increasing. Remarkable enough is also the difference in dist
ances between the endothelium and SMC on the one hand and nerve varico
sities and SMC on the other. The above facts indicate a prevalence of
endothelial control of coronary diameter.