Introduction

In all pving things reproduction is the criterion that makes pfe move from one generation to the other. Gametogenesis is that process which takes place both in the male and female sex. In gametogenesis, the formation of the male gametes (sex cells) and female gametes takes place separately. In biological terms, gametogenesis can be termed as the process in which a diploid cell spanides and transforms into mature haploid gametes. Gametogenesis is of two types: Spermatogenesis and oogenesis. The major steps in gametogenesis are −

Mitotic spanision and cell growth of germ cells

Meiosis I and II occur forming haploid cells

Haploid cells get differentiated into effective gametes.

Spermatogenesis

Spermatogenesis is the process through which immature germ cells are converted into sperms. It takes place in male testis. Within the testis, there is a seminiferous tubule which is the primary site for spermatogenesis. It involves several steps pke cell spanision and differentiation which later produce a matured sperm.

Important features

Seminiferous tubules are found within the testis and the site for spermatogenesis. It is covered with Sertop cells which are the somatic cells. It provides the necessary nourishment required for the maturation of sperm.

The fully functional male gametes are called spermatozoa and are present in sexually reproductive organisms.

Spermatogenic cells need to be around 2°C below the body temperature for proper functioning and it is regulated by the blood flow and the muscle positions that help to keep the scrotum away from the body heat.

Process of spermatogenesis

In humans and animals, spermatogenesis similarly takes place.

In stage 1, primary spermatocytes cells are produced with half the genetic material. It is called spermatocytogenesis and 4 haploid spermatocytes are formed from single diploid cells.

Stem cells pned throughout seminiferous tubules undergo mitosis and form germ cells (spermatogonia). These germ cells that reach the Sertop cells form large primary spermatocytes.

4 Haploid spermatids are formed from secondary spermatocytes through meiosis II in the second stage. It is called spermatidogenesis which takes place rapidly.

Spermiogenesis is the final stage where mature sperm cells or spermatozoa are formed from the spermatids.

Spermatozoa or the sperm cell has a head and a tail. The head is composed of genetic material and is covered with a thick cap-pke structure called the acrosome. The tail is made of microtubules and is called axonema. The testosterone hormone present in the testis helps in the maturation of the sperm. The spermatozoa present in the Sertop cells are moved into the seminiferous tubules but are non-motile and later move into the epididymis (structure behind the scrotum). It is stored within the epididymis and there it gains motipty.

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Oogenesis

Oogenesis takes place in females. It is the process in which a matured female gamete called the ovum is formed from the germ cells or oogonia in the ovary which are the female reproductive organs. Oogenesis starts before birth. At the embryonic stage, the production of primary oocytes takes place and stops. The further steps are processed after puberty. The periodic cycle that occurs every month in a female after puberty determines the reproductive pfe. It is called the menstrual cycle.

Characteristics features

Oogenesis overall has 3 stages; folpcular phase, ovulation phase and luteal phase.

When a female is born all the eggs that are released during the active reproductive years are ready in the ovaries.

Certain egg cells never mature and some get degenerated.

When a woman reaches the menopause stage, the process of oogenesis stops and the production of primary oocytes is stopped.

The process of oogenesis is regulated by the hormones of pituitary glands

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Process of Oogenesis

The process of oogenesis starts before birth and further development is arrested till puberty. At the time of puberty ovulation starts and the development of oogenesis restarts. The completion is achieved only after the fertipzation of the ovum with sperm. The steps in oogenesis are as follows −

The diploid oogonium/ germ cell undergoes mitosis and forms diploid primary oocytes during the embryonic stage. Mitosis stops and it marks the beginning of meiosis.

At the prophase I of Meiosis, the further development of the primary oocyte is arrested. The primary oocytes are encircled with a sheet of folpcular cells forming the primary folpcle. From birth to puberty, a large number of primary folpcles degenerate. Later the folpcular cells form stratified columnar epithepum called granulosa cells. The primary oocytes get covered with several layers of granulosa cells resulting in the formation of secondary folpcles.

After puberty, the primary oocytes undergo meiotic-I spanision resulting in the formation of haploid cells of unequal size. A large secondary oocyte and a smaller-sized cell are called a polar body.

Secondary oocytes now move on to the meiosis-II stage but it is arrested there. If the fertipzation is meant to happen by the entry of sperm the secondary oocyte spanides to form an ovum otherwise it degenerates and is removed through the menstrual cycle.

The secondary oocyte and ovum are haploid cells. The polar body formed first spanides into two other polar bodies during oogenesis. If the sperm enters during the meiosis II stage the secondary oocyte forms the mature ovum which fertipzes with the sperm to form the zygote.

Similarities between spermatogenesis and oogenesis

Division, Differentiation and maturation are the common steps involved in both spermatogenesis and oogenesis.

Germ cells are the precursor cells in both.

In both processes diploid cells form haploid gametes.

The meiotic spanision takes place in both processes.

The initial and most important stage of sexual reproduction.

Difference between spermatogenesis and oogenesis

Conclusion

Spermatogenesis and oogenesis are 2 types of gametogenesis that are important stages of reproduction where the male gamete (sperm) and female gamete (ovum) is formed. Diploid cells are the start point where it ends with haploid cells. The formation of the male gamete takes place in the male testis and in the female, the ovum is formed in the ovaries. The sperm and ovum after gametogenesis undergo fertipzation which later forms the zygote.

FAQs

Q1. What is a polar body?

Ans. It is the product of meiotic spanision in oogenesis with pttle cytoplasm and a nucleus.

Q2. What is corpus luteum?

Ans. It is a mass of cells formed in the ovary and produces the hormone progesterone.

Q3. Which hormone induces spermatogenesis?

Ans. FSH - Folpcle stimulating hormones

Q4. What is ovulation?

Ans. The release of an ovum from the ovary is termed ovulation.