Kharchenko S.V., Associate Professorof the Histology and Embryology DepartmentMedical Academy named after S.I.Georgievsky

HUMAN EMBRYOLOGY

The structure of the spermcell (spermatozoa) is the male sex cell, which develops in the testis. It is a small cell capable of active movement.

The sperm cell consists of three parts: the head, the neck (connecting part) and the tail.

The head inside contains: a nucleus, which is large in size and occupies almost the entire volume of the head; the cytoplasm is present in the head in the form of a narrow ring around the nucleus. The nucleus contains a haploid set of chromosomes (23 chromosomes, one of which is sex).
The acrosomeis located above the nucleus. It is a derivative of the Golgi complex. The acrosome contains enzymes. They are called spermolysins (hyaluronidase, acrosin). Acrosome enzymes are essential for the fertilization of the female reproductive cell.

Outside on the plasmolemmaof the front of the head, the sperm contains glycosyltransferase- a sperm receptor that allows it to recognize the egg of its own species.

The connecting part or neck of the sperm contains two centrioles - proximal and distal. The axoneme begins from the distal centriole - this is the most important component of the tail.

The sperm tail includes three parts:

- middle piece

- principal piece

- end (terminal) piece

The middle piecehas an axoneme and mitochondria.

The axoneme consists of 9 doublets of peripheral microtubules and one doublet of central microtubules. Axoneme formula (9X2) +2. Each microtubule is made up of a protein called tubulin. Microtubules of neighboring doublets are connected using a dynein. It is a contractile protein. It has ATPase activity. It uses ATP molecules for its contraction. Thanks to him, the sperms is actively move.

The mitochondrion is located around the axoneme in the form of a spiral. It generates energy that dynein uses to contract.

The principal piececontains an axoneme around which fibrils are spirally located and form curcumferential fibrils. There are also outer fibrils along the axoneme in this part of the tail which form longitudinal columns of fibrils.

The terminal piece consists of individual thin filaments.

see below the structure of the sperm cell

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