Spicules are needle-like structures, which after crosslinking give shape to the sponge. These are present in the mesohilo, which is the central layer of the three present in sponges.
There are three types of skeletons in sponges, which are classified according to the type of beak they present. Spicules are made up of a special set of cells called sclerotia. The first type of skeleton that sponges can present does not have spicules, because in these sponges the sclerotia form threads of a protein called spongin, the cells that form this type of skeleton are called “spongioblasts”. Among the sponges of this type are used for cosmetic purposes.
Depending on the growth and formation of the spicules, they can be classified into microsclera (small spicules) and microsclera (large spicules). Within the second group we can differentiate those that grow along three axes, called taxa, which are divided into triactiv elide and hexactinellid and those that grow in a single axis.
Among the latter are monoacetalide, which grows in one direction, and acetanilide, which grows in both directions of the axis. All of the spicules discussed so far are quite simple in their morphology, however there are other more complex types of spicules. Some of them are called polyaxial, consisting of more than three radii, and others may have shapes close to circular ones.
Its function is to dilate the vulva of the females and thus allow the mating of the male genital organs with the female genital organs, these are guided by the governor. Depending on the nematode subclass, they may or may not have spicules: No spicules, Adenophorea Subclass: Fam. Trichinellidae. 1 spike, Subclass of Adenophorea, Fam Trichuridae and Subclass of Secernentea, Order Oxyurida. 2 spicules, Subclass Secernentea.
