● The `color{Violet}"primary sex organs"` – the `color{Violet}"testis"` in the males and the `color{Violet}"ovaries"` in the females – produce `color{Violet}"gametes"`, i.e, sperms and ovum, respectively, by the process called `color{Violet}"gametogenesis"`.

`=>` `color{blue}"Spermatogenesis"` : The process of development of `color{Violet}"spermatozoa from spermatogonia"` in a male gonad in an animal via mitosis and meiosis.

`=>` `color{blue}" Spermatogonia"` : The diploid cell that arises from `color{Violet}"male germ cell"` and gives rise through mitosis to the `color{Violet}"spermatocytes"`. They are found in the testes of vertebrates.

`=>` `color{blue}"Spermiation"`: It is the process when mature `color{Violet}"spermatozoa embedded"` in the `color{Violet}"sertoli cells"` are released from the sertoli cells into the lumen of seminiferous tubules.

`=>` `color{blue}"Spermiogenesis"` : It is the process of `color{Violet}"transforming spermatids"` into `color{Violet}"matured spermatozoa"` or sperms.

`color{green} ✍️ color{green} mathbf("KEY CONCEPT")`

● In testis, the immature male germ cells (`color{Violet}"spermatogonia"`) produce sperms by `color{Violet}"spermatogenesis"` that begins at `color{Violet}"puberty"`.

● The spermatogonia (sing. spermatogonium) present on the `color{Violet}"inside wall"` of seminiferous tubules multiply by `color{Violet}"mitotic division"` and increase in numbers.

● Each spermatogonium is `color{Violet}"diploid"` and contains `color{Violet}"46"` chromosomes.



● Some of the spermatogonia called `color{Violet}"primary spermatocytes"` periodically undergo `color{Violet}"meiosis"`.

● A primary spermatocyte completes the `color{Violet}"first meiotic division"` (reduction division) leading to formation of `color{Violet}"two equal"`, haploid cells called `color{Violet}"secondary spermatocytes"`, which have only `color{Violet}"23"` chromosomes each.

● The secondary spermatocytes undergo the second meiotic division to produce `color{Violet}"four"` equal, `color{Violet}"haploid spermatids"` .

● The spermatids are transformed into `color{Violet}"spermatozoa"` (sperms) by the process called `color{Violet}"spermiogenesis"`.

● After spermiogenesis, sperm heads become `color{Violet}"embedded"` in the `color{Violet}"Sertoli cells"`, and are finally released from the seminiferous tubules by the process called `color{Violet}"spermiation"`.

● Spermatogenesis starts at the age of `color{Violet}"puberty"` due to significant increase in the secretion of `color{Violet}"gonadotropin releasing hormone"` `color{Violet}"(GnRH)"`( Hypothalamic Hormone).

● The increased levels of GnRH then acts at the anterior pituitary gland and stimulates secretion of two gonadotropins – `color{Violet}"luteinising hormone (LH)"` and `color{Violet}"follicle stimulating hormone (FSH)"`.

● LH acts at the `color{Violet}"Leydig cells"` and stimulates synthesis and secretion of `color{Violet}"androgens"`.

● Androgens, in turn, stimulate the process of `color{Violet}"spermatogenesis"`.

● FSH acts on the `color{Violet}"Sertoli cells"` and stimulates secretion of some factors which help in the process of `color{Violet}"spermiogenesis"`.

● It is a `color{Violet}"microscopic structure"` composed of a head, neck, a middle piece and a tail.

● A `color{Violet}"plasma membrane"` envelops the whole body of sperm.

● The sperm head contains an elongated haploid `color{Violet}"nucleus"`, the anterior portion of which is covered by a cap-like structure, `color{Violet}"acrosome"`.

● The acrosome is filled with `color{Violet}"enzymes"` that help `color{Violet}"fertilisation"` of the ovum.

● The middle piece possesses numerous `color{Violet}"mitochondria"`, which produce energy for the movement of tail that facilitate `color{Violet}"sperm motility"` essential for fertilisation.

● The human male ejaculates about `color{Violet}"200 to 300 million"` sperms during a coitus.

● Of this for normal fertility, at least `color{Violet}"60 per cent sperms"` must have normal shape and size

● At least `color{Violet}"40 per cent"` of them must show vigorous motility.

● Sperms released from the seminiferous tubules, are transported by the `color{Violet}"accessory ducts"`.

● `color{Violet}"Secretions"` of epididymis, vas deferens, seminal vesicle and prostate are essential for `color{Violet}"maturation"` and `color{Violet}"motility"` of sperms.

● The `color{Violet}"seminal plasma"` along with the `color{Violet}"sperms"` constitute the `color{Violet}"semen"`.

● The `color{Violet}"functions"` of male sex accessory ducts and glands are maintained by the testicular hormones (`color{Violet}"androgens"`).