In OEdogonium the fertilization is effected by a spermatozoon fusing with an oosphere (ovum).
Remarkable changes of size and outline of the oosphere have recently been described as accompanying fertilization in Hallidrys.
In such a case the zoogamete is male, is called an antherozoid or spermatozoid, and arises in an antheridium; the larger gamete is an oosphere and arises in an oogonium.
The oosphere is in all cases fertilized while still within the oogonium, the antherozoids being admitted by means of a pore.
It is interesting to know, on the authority of Oltmanns, that when the oosphere is forming in the oogonium of Vaucheria, there is a retrocession of all the included nuclei but one.
The doubling process is provided by the act of fertilization, where an antherozoid with the single number of chromosomes fuses with an oosphere also with the single number to provide a fertilized egg with the double number.
In rare cases theoosphere has been known to germinate without fertilization (Oedogonium, Cylindrocapsa.
Dictyota the unfertilized oosphereis found to be capable of undergoing a limited number of divisions, but the body thus formed appears to atrophy sooner or later.
This is the carpogonium: it consists of a neutral portion which contains a nucleus, but in which no oosphere is differentiated, and an elongated tubular portion known as the trichogyne, into which the cytoplasm extends.
After impregnation the fertilized oosphere immediately surrounds itself with a cell-wall and becomes the oospore which by a process of growth forms the embryo of the new plant.
In Coleochæte, the male cell is a round spermatozoid, and the female cell an oosphere contained in the base of a cell which is elongated into an open and hair-like tube called the trichogyne.
The protoplasm in one of these protuberances arranges itself into a round mass--the oosphere or female cell.
These are of the ordinary type of those organs, namely, a broad lower portion, containing a naked oosphere and a long narrow neck with a central canal leading to the oosphere.
The product of the union of an antherozoid and an oosphere is termed an oospore.
Oogonium with the central uninucleate oosphere and the fertilizing tube (a) of the antheridium which introduces the male nucleus.
We thus have a process of "multiple fertilization"; the oosphere really represents a large number of undifferentiated gametes and has been termed a coenogamete.
In Cystopus Bliti the oosphere contains numerous nuclei, and all the male nuclei from the antheridium pass into it, the male and female nuclei then fusing in pairs.
The above list will hopefully give you a few useful examples demonstrating the appropriate usage of "oosphere" in a variety of sentences. We hope that you will now be able to make sentences using this word.
