Category: Video Lectures

This video is about the structure of Nephridia of Neres. It is an excretory organ of Neres, which is a Polychete Annelidan. Neres has Metanephridia which are exonephric type. There are one pair nephridia per segment except the head segments and pygidium. In structure nephridia have a syncytial connective tissue body consisting of nephridial tubule and the neck. The tubule opens at one end by Nephrostome and by nephridiopore at other end. The neck lies dipped into coelom of the adjacent segment and the nephridiopore opens outside in which body lies transversally in ventro lateral position. The waste products are absorbed by gland cells of nephridial tubule and by ciliates nephrostome and discharged outside through nephridiopore.

This video is about the morphology of the chromosome. Chromosomal body has elongated highly coiled DNA fibrils known as chromonema which are embedded in the matrix and matrix is covered with the pellicle. The size, shape and number of chromosome are fixed according to species. Organism having one set of chromosome are Haploid(n), with double set they are diploid, more than two set are known as polyploids.