Nephrostom or Ciliated Funnel UNCI VNUA Nervous System
Form and function in animals 39 Excretory system The excretory system is segment-organised, microscopic, coiled and complex, kidney-like, carried out by specialized tubes called segmental organs or nephridia. In the ferratum, nephridia are in all segments except the first three and are distinguished according to their position in the body into three types: (1) septal, (2) pharyngeal and (3) integumentary. Septal nephridia are the largest and are attached to both faces of each inter-segmental septum behind the 15th segment. Structure: A typical septal nephridium consists of three main parts- the nephrostome, the body, and the terminal duct, the nefridial duct. (a) Nephrostome: Nephrostome or ciliated funnel is a circular structure which opens by an elliptical orifice surrounded by ciliated cells in the coelom. The so-called upper lip of the nephrostom is composed of a large central cell and eight or nine marginal cells. The so-called lower lip is composed of four or five compact cells.
This is followed by a short, narrow, ciliary tube, the neck, which is bent over it. (b). Body of nephridia: The neck moves into the main body of nephridia consisting of two parts a short straight lobe and a long spirally folded loop with a narrow apex. (i) (ii) The loops can again be identified as a proximal and a distal organ spirally twisted on them. The distal organ is attached directly to the lobe, while the proximal organ is attached to the neck and continues as the terminal duct of the nephridia.
Terminal Duct: It is a short, narrow and ciliated tube which goes into the septal excretory duct on its side. (d) Nefridial Duct: Nephridia consist of a glandular mass that is bounded by a coiled nephridal duct or tubule, the course of which consists of four ciliated tracts, one in the neck, two in the body and one in the terminal duct. The straight lobe has four parallel ducts, three in the basal and two in the apex of each limb of the bent lobe, and a single duct in each neck and terminal duct.
FORM AND R UNCI VNUA Nervous System A pair of cerebral ganglia connected by a transverse nerve band and a ganglionated ring commissure in the scolex. Five pairs of longitudinal nerves travel in the strobilla. Excretory system It consists of flame cells and four main excretory ducts, of which only two extend to the last proglottid and open through a common excretory pore. When the last proglottid is lost by apolysis, the two excretory ducts open separately. Reproductive System Tapeworms are hermaphrodite. Each proglottid, at maturity, has a complete set of male and female reproductive organs.
The male organs differentiate before the female organs (protenderous position), so that in the mature region of the strobilla, consisting of about 450 proglottids, the anterior 100–150 proglottids have only the male system, while the remaining posterior ones have both male and female systems. Huh. After a period of intense reproductive activity, the mature proglottid loses all of its genital organs except for a highly branched uterus filled with fertilized eggs.
Sections that have reached this stage are called ripe or gravid segments. Transverse excretory canal lateral nerve cord testis. excretory.
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