Structural Organisation Of Animals And Plants

Once being differentiated, nerve cells do not divide as they lack mitotic activity. Lack of mitotic activity indicates that they do not have centrosome

Answer (d) It has 13-chambered heart and in each segment one pair of ostia are present

Astrocytes are large sized star shaped cells which form an interconnected network around neurons. Astrocytes secrete basal lamina around blood vessels and constitute blood-brain barrier.