Histological and histochemical characteristics of the bovine notochord.

In 20 bovine embryos and fetuses 6-65 mm long (crown-rump length) and 23 to 60-70 days old, the structure and localization of acid and neutral mucopolysaccharides and glycogen in their notochord were investigated. Also, the localization in the notochord was examined of the activity of alkaline and acid phosphatases, alpha-glycerophosphate-, glucose-6-phosphate-, isocitrate-, glutamate-, lactate- and succinic- dehydrogenases, and nicotinamide-adenine-dinucleotide- and nicotinamide-adenine-dinucleotide-phosphate- diaphorases. It was found that the bovine notochord begins decomposing at the end of embryonal and the beginning of fetal development (45-50 days old) and that in the fetus aged 55-65 days it no longer represents an unbroken cord of notochordal cells. Secretory activity of notochordal cells which produce the notochordal sheath starts very early (in 10 mm-long embryos), and interruptedly increases up to the end of the embryonal developmental period when regression appears at the beginning of the fetal period. These findings agree with findings in the human embryo where, however, they relate to earlier developmental periods.