Difference between Oogenesis and Spermatogenesis

Every human body was first a single zygote formed, a cell produced through sperm and an egg. The cycle where male and female germs are produced is called Gametogenesis. These sperms and eggs are the males’ and females’ reproductive cells, also responsible for fertilization. After fertilization, the zygote grows, disintegrates, and develops into different tissues such as epithelial and connective tissue, and further organs, transforming into an entire human. The sustenance of any animal depends on its reproductive ability.

So, it all relies on the process and whether the newborn would be a male or a female. Hence, it’s essential to understand the primary cells, sperms, and eggs. That is why we presented this article to differentiate between Oogenesis and Spermatogenesis.

Gametogenesis for sperm formation is known as Spermatogenesis. On the contrary, the process for egg (ova) formation is called Oogenesis. Oogenesis is the process by which female (ova) gametes are formed. The meiosis process in female gametes is distinct from that of males, comprising four haploid gametes from a single diploid cell.

In Spermatogenesis, spermatozoa develop in the seminiferous tubules of the testis from germ cells. In addition, it is a complex process involving the division of mitotic cells and starts at puberty to continue for the rest of a male’s life. Both gametes are haploid cells that carry 23 unpaired chromosomes, half the human genetic makeup.

Comparison Table

Basis of Comparison	Oogenesis	Spermatogenesis
Description	Formation of female eggs	Sperm formation (masculine gametes)
Origin	Develops from the germinal epithelium	Emerges from seminiferous tubules
No. of Gametes Produced	A single egg	Four sperms
Food Reserve	Plenty of food	Little food amount
Division Product	One oogonium alone produces oocytes.	All spermatogonia break up to form spermatozoa.
Cell Differentiation	Not present.	Present
Nucleus	In uncondensed form	Undergoes condensation.
Meiosis-II Products	One ovum and one polar body	Two spermatids
Reproduction	Ootids engage in the reproduction cycle	The spermatids convert to sperm to held reproduction.
Size	Eggs are greater in size than oocytes	Sperm is smaller than spermatozoa

What is Oogenesis

Oogenesis is the formation of female embryos. This process occurs within the ovary in females, where the oogonium develops from the germinal epithelium surrounding the ovary. Furthermore, this cycle is pretty discontinuous and takes a duration of a few days to even years. Oogenesis has two divisions of maturation, with the first one completed in the ovaries, while the second takes place outside the cell after fertilization.

When an oogonium develops from the germinal layer, it undergoes mitosis and cytokinesis to transform into a primary oocyte (2n). This oogonium has a self-renewing capacity too. The primary oocyte takes Meiosis-I into account and differentiates into the secondary oocyte and one polar body (n). If the female did not reach puberty, the process would stick to the diplotene stage till the woman reaches puberty to release eggs. In other words, the secondary oocytes involve Meiosis-II to reach the metaphase and finally form ootids. Eventually, the formed ootid continues fertilization to produce a large, non-motile ovum that engages a sperm to produce a zygote. It also produces a second polar body.

Besides, unlike the male gametes that continuously produce from puberty onwards, female gametes start producing before birth but mature when the woman hits puberty.

Stages of Oogenesis

Oogenesis is the process of formation and maturation of female gametes, known as ova or egg cells. It occurs in the ovaries and involves several distinct stages:

• Primordial Germ Cell Stage: During embryonic development, primordial germ cells migrate to the gonadal ridge and become oogonia, which are the precursors of ova.
• Multiplication Stage: The oogonia undergo several mitotic divisions to produce primary oocytes.
• Growth Stage: The primary oocytes increase in size and accumulate nutrients in preparation for the next stage.
• Meiotic Prophase I: The primary oocyte initiates the first meiotic division but arrests at the diplotene stage of prophase I, a state known as the dictyate or resting stage.
• Maturation Stage: After puberty, in response to hormonal signals during each menstrual cycle, one primary oocyte resumes meiosis I and completes it, forming a secondary oocyte and a polar body.
• Ovulation: The secondary oocyte undergoes meiosis II, but this division is arrested at metaphase II until fertilization occurs.
• Fertilization: Upon fertilization by a sperm cell, the secondary oocyte completes meiosis II, extruding a second polar body and forming a mature ovum (haploid egg cell) and a second polar body.

It’s important to note that in humans, only one oocyte typically completes maturation and ovulation during each menstrual cycle, while the remaining primary oocytes degenerate.

What is Spermatogenesis

On the other hand, spermatogenesis is simply the formation of sperms. This process takes place inside the male testis. The germinal epithelial lining of a seminiferous tubule produces a spermatogonium. It’s again a diploid stem cell, having the potential to renew itself. Besides, the process continues and finishes in around 74 days. When this spermatogonium undergoes mitosis, it turns to the primary spermatocytes through a distinct process called spermatocytogenesis. These primary cells are responsible for producing two secondary spermatocytes through Meiosis-I. The formed secondary cells further undergo Meiosis-II to produce spermatids, connecting through the lumen.

Spermatids are non-flagellated, round cells that cannot take part in fertilization. Hence, they continue to mature from the haploid and motile spermatozoa/sperms. This process is also termed Spermiogenesis. Moreover, the sperms are condensed, thread-like structures whose growth period is relatively shorter.

Stages of Spermatogenesis

Spermatogenesis is the process of formation and maturation of male gametes, known as spermatozoa or sperm cells. It occurs in the seminiferous tubules of the testes and involves several distinct stages:

• Spermatogonial Stage: Spermatogonial stem cells, located in the seminiferous tubules, undergo mitotic divisions to produce primary spermatocytes.
• Meiotic Prophase I: The primary spermatocytes initiate the first meiotic division and progress through the stages of prophase I, including leptotene, zygotene, pachytene, diplotene, and diakinesis.
• Meiosis I: During meiosis I, the primary spermatocytes divide into two haploid secondary spermatocytes, each containing half the number of chromosomes.
• Meiosis II: The secondary spermatocytes immediately undergo meiosis II, dividing into four haploid spermatids.
• Spermiogenesis: The spermatids undergo morphological transformations, including the formation of the acrosome, condensation of the nucleus, and development of the flagellum (tail), to become mature spermatozoa.
• Spermiation: The mature spermatozoa are released from the seminiferous tubules into the lumen, where they undergo further maturation and gain motility.

Oogenesis vs Spermatogenesis

Let’s have a detailed overview of the differences between oogenesis and spermatogenesis.

Production & Location

Where Does Oogenesis Occur

When an oogonium undergoes the splitting cycle, it produces eggs through the process called oogenesis. It takes place inside the ovaries except for the last stage, which occurs in the oviduct.

Where Does Spermatogenesis Occur

On the contrary, the origination of sperm from spermatogonia takes place through a process called spermatogenesis. It always occurs inside the male testis.

Nature of Continuity

Oogenesis

This process begins even before a female is born, but the maturation starts at puberty. Only a single ovum (egg) produces every month till the menstrual cycle lasts.

Spermatogenesis

In contrast, spermatogenesis is a continuous process that only stops at death.

Number & Size of Gametes

Oogenesis

Only a single ovum is produced from one oocyte, which is bigger than that.

Spermatogenesis

On the other hand, a spermatocyte forms four spermatids, smaller in size than the parent cell.

Role of Germinal Epithelial Lining

Oogenesis

This particular layer produces oogonium, which has to continue the gamete formation process.

Spermatogenesis

In contrast, spermatogonia develop from this layer of the seminiferous tubules.

Division of Cells

Oogenesis

The cell divides only when there is time to produce an egg, one in a month.

Spermatogenesis

On the other hand, cell division continues all the time with the help of meiosis I and II.

Growth Phase

Oogenesis

It has a prolonged growth phase in oogonium.

Spermatogenesis

On the contrary, it has a relatively shorter growth phase in spermatogonia.

Motility

Oogenesis

The process ends up at non-motile gametes, also called eggs.

Spermatogenesis

On the other hand, this process ends up at the motile gametes (sperms).

Preservation of Food

Oogenesis

An ovum consists of a large amount of food and bio-chemicals.

Spermatogenesis

In contrast, sperms do not reserve a sufficient food quantity.

Conclusion

Both the terminologies are hence entirely different from each other. Oogenesis always takes place in females, whereas spermatogenesis arises in males. Despite being dissimilar, both oogenesis and spermatogenesis undergo three significant phases of life, multiplication, maturation, and differentiation. But the good part is that both form gametes that are utilized in fertilization to form a zygote.