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Trematodes are covered by a tegument, that protects the organism from the environment by providing secretory and absorptive functions. The life cycle of a typical trematode begins with an egg. Some trematode eggs hatch directly in the environment (water), while others are eaten and hatched within a host, typically a mollusc.
Usually there is a single ovary with an oviduct, a seminal receptacle, a pair of vitelline glands (involved in yolk and egg-shell production) with ducts, the ootype (a chamber where eggs are formed), a complex collection of glands cells called Mehlis’ gland, which is believed to lubricate the uterus for egg passage.
The trematode Hirudinella ventricosa releases eggs in strings. Each egg contains a single miracidium, while the string contains living spermatozoa. Miracidia have cilia that are only present in the upper portion of the body near an apical gland with 12 hook-like spines in the opening. [2]
The eggs, which are oval, operculated, and light brown, are released from adult Alaria and excreted from the final host's faeces and hatched into miracidium that infect the snail host, in which the eggs then give rise to the asexual stage known as sporocysts. The sporocysts then produce cercariae.
The goal of cellular manufacturing is to move as quickly as possible, make a wide variety of similar products, while making as little waste as possible. Cellular manufacturing involves the use of multiple "cells" in an assembly line fashion. Each of these cells is composed of one or multiple different machines which accomplish a certain task.
Egg of S. haematobium. Note the pointed spine on the left tip. Normal infection of adults does not produce symptoms. When eggs are released, they sometimes become permanently stuck in the bladder and cause pathological symptoms. The eggs are initially deposited in the muscularis propria which leads to
The ova is yellowish in color. The egg is about 70–85 μm long by 44 μm wide, and the early stages of cleavage contain between 16 and 32 cells. The adult female is 18–30 millimetres (3 ⁄ 4 – 1 + 1 ⁄ 8 in) long and is easily recognized by its trademark "barber pole" coloration.
The number of eggs that the insect is able to make varies according to the number of ovarioles, with the rate at which eggs develop being also influenced by ovariole design. In meroistic ovaries, the eggs-to-be divide repeatedly and most of the daughter cells become helper cells for a single oocyte in the cluster. In panoistic ovaries, each egg ...