The seminiferous tubules are located in the testes and are the location of spermatogenesis.
Sertoli cells are the “nurse” cells of the testes. They nourish developing sperm cells, and create the blood-testis barrier.
Spermatogonia are the diploid parent cells in spermatogenesis. They have copies of each chromosome from the original parents of the organism.
This is an important difference between male and female humans. Females have a set amount of eggs at birth, while males can produce more spermatogonia. Mitosis is also used to produce primary spermatocytes, which then enter meiosis.
The primary spermatocytes are formed by mitosis of a spermatogonium and are diploid intermediate cells. Each of them moves into the adluminal compartment of the seminiferous tubules.
The primary spermatocyte enters meiosis I, duplicates DNA, and then divides into two haploid secondary spermatocytes. This creates genetic variation between spermatocytes and spermatids because of crossing over and recombination.
The secondary spermatocyte is a haploid cell produced from meiosis I of a primary spermatocyte. It enters meiosis II to divide into haploid spermatids.
The secondary spermatocyte undergoes meiosis II to become a spermatid. In males, four functional spermatids are produced for each spermatogonium. Keep in mind that in female oogenesis, only one functional cell is produced from meiosis, as the other two are polar bodies.
Spermatids are the product of meiosis II and are haploid with 23 chromatids. Spermatids are still not mobile, but begin to develop a thick middle piece where mitochondria are located as well as an acrosome.
Spermatozoa are motile sperm cells that are haploid. They are the cells that fuse with ovums to form zygotes.
An acrosome is an organelle that is located over the anterior half of the spermatozoa head. Digestive enzymes located in it help break down the outer membrane of the ovum (zona pellucida) allowing fusion to occur.
A flagellum is an appendage that protrudes from the cell bodies of spermatozoa. It functions as both a sensory organ and a locomotion organ.
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