Oogenesis vs Spermatogenesis Definition, Differences, & Comparison

Spermatogenesis vs Oogenesis, both terms are related to the human reproduction system. Human reproduction is a highly complex mechanism where gamete formation is the initial step required for fertilization.

Gametes are basically the reproductive cells which are produced within specialized organs. In females, the reproductive organ required for gamete formation is called an ovary and the reproductive cell formed within is called an Ovum however on the other side, sperms are the gametes which are formed within testes of men. This mechanism of gamete formation is what known as gametogenesis.

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Once these gametes are formed, fusion of these together results in the fertilization of female egg called ovum which results in the formation of zygote whose continuous division of cells results in a complete and individual offspring.

An ovum and a sperm, however they are gametes but they are entirely different from each other. The mechanism of formation of ovum is known as oogenesis and the production of sperms is what is known as spermatogenesis. Collectively these two distinctively related processes are called as Gametogenesis.  So, in other words it can be said that gametogenesis is of two types namely Spermatogenesis and Oogenesis.

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Spermatogenesis:

When a male individual reaches the age of puberty, his body starts to produce sperms. The quantity of sperms which are produced within the testes of males per day is large ranging to 200 million. These sperms reach eggs of a female when a male individual ejaculates. These are formed within the seminiferous tubules which are present inside testes. These tubules are specialized places of meiosis process. The cells of these tubules are tubular shaped and are the production centers of sperms.

During this mechanism, spermatogonium is the diploid cell which undergoes the process of mitosis to give rise to two diploid cells. These resulting diploid cells are called as primary spermatocytes. Each of these cells migrates towards Adluminal compartment where they undergo the process of duplicating its DNA. Duplication of DNA by the process of meiosis results in the production of 2 haploid primary spermatocytes. These 2 haploid primary spermatocytes divide once again to produce a total of 4 haploid spermatids. This procedure is what is responsible for the genetic variation found within individuals due to chromosomal crossovers occurring within the process of meiosis.

All of the spermatogonia do not divide at once. If this occurs, the supply of spermatogium would run out. For this purpose, stem cells continuously divide themselves to produce new spermatogium so this process can continue. The production of spermatids from haploid primary spermatocytes is called as Spermatidogenesis. Sperms results from these haploid spermatids through the operation of Spermiogenesis. This is the maturation step. During this process, the cytoplasmic barrier or bridge is broken which releases these spermatids into the lumen and is called as Spermiation. Once these spermatids are released into the lumen, they undergo remodeling. This is the last step of spermatogenesis which remodels a spermatid into mature spermatozoa. Roughly, this process of Spermiogenesis is divided into 4 stages. These stages include, Golgi phase, cap phase, tail phase, and maturation phase.

1.     Golgi phase:

During this phase, spermatids develop heads. The golgi apparatus is responsible for producing enzymes which will develop the head or acrosome. At the end of acrosome, the tail is formed which is called as the axoneme. The DNA also becomes highly condensed by going through the process of packaging. This DNA is packaged with basic proteins which are later replaced by protamines during the elongation operation. The chromatin which results is not active transcriptionally.

2.     Cap phase:

During this phase, the acrosomal cap is formed by golgi apparatus whih encircles the condensed nucleus of spermatids

• Tail phase:

During the tail formation phase a centriole elongates to make the tail. This process is assisted by a structure which is called as manchette, assisting in the process of elongation and later disappears. These spermatozoa arrange themselves such that their tail points away from epithelium and towards the lumen’s center.

4.     Maturation phase:

During the maturation phase of spermiogenesis, the Sertoli cells remove the excessive cytoplasm which is present by the procedure of phagocytosis. The resulting spermatozoas are functionally active sperms.

Oogenesis:

Oogenesis differs from spermatogenesis because in oogenesis and spermatogenesis is that oogenesis initiates within a fetus way before birth. This process starts when oogonia converts into primary oocytes. This transformation of oogonia into primary oocyte is termed as oocytogenesis. This process is usually completed before birth or shortly afterwards.

The process of Oogenesis

Primary oocytes:

It is said that when oocytogenesis has been completed then no further oocytes are formed unlike the spermatogenesis in males in which males’ stem cells within testes continues to produce new spermatocytes. The maximum production and development of primary oocytes have been completed within 20 weeks of gestational period. At this time, around 7 million primary oocytes have been produced and at the time of birth, this number gets reduced to 1 to 2 million respectively.

Ootidogenesis:

The primary oocytes after creation go through the proceeding of meiosis to produce an ootid. This process is termed as ootidogenesis. It can be said that the main function of these primary oocytes is to mature by the process of meiosis.  This step which starts at this age stops when it reaches the step of prophase. So we can say that all oocytes are in a stage of halt until and unless the female reaches the age of puberty where a few primary oocytes mature during each menstrual cycle of the month to produce a mature egg for fertilization.

Meiosis I

As it has been mentioned before that the primary oocytes generated go through meiosis to produce ootids but after that this process stops at the prophase 1 stage until the female individual reaches the age of puberty.

Meiosis II

Once, the meiosis 1 has been completed, meiosis 2 initiates within secondary oocyte. This mechanism also stops when it reaches the stage of metaphase 2 until the stage of fertilization. If the produced egg does not undergo the process of fertilization then the egg is released through disintegration following menstruation. Menstruation is the process by which this egg is expelled out of the body if not fertilized. If this happens, the secondary oocyte which was formed does not mature into an ovum and does not go through meiosis 2. Once the meiosis 2 has been completed, it results in the formation of an ootid along with a smaller body which is called as the polar body.

What are the products of meiosis I in oogenesis?

Because of meiosis I, the essential oocyte forms into the auxiliary oocyte and the principal polar body. For those essential oocytes that keep on creating in each menses cycle, nonetheless, synapsis happens and quadruplicates structure, empowering chromosomal hybrid to happen.

Folliculogenesis

When ootidogenesis occurs, the follicle which surrounds the ootid develops into preovulatory follicle from primordial one.

Maturation (Ovum formation)

Once the process of meiosis 2 has been completed, the polar bodies are disintegrated. It leaves only an ootid in the end. This ootid eventually matures into an ovum. The purpose of these polar body formations is to remove the extra chromosomal sets which have been formed due to meiosis.

how does spermatogenesis differ from oogenesis?

The basic difference between spermatogenesis and oogenesis is that the process of oogenesis relates to the female reproductive framework while spermatogenesis to the male reproductive framework.

Difference between spermatogenesis and oogenesis

Spermatogenesis	Oogenesis
Spermatogenesis is the production of sperms by the process of gametogenesis.	Oogenesis is the process of formation of eggs by the process of gametogenesis.
This process occurs within testes of male individuals.	This process occurs within ovary of female individuals.
All stages of spermatogenesis occur within testes of males.	Majority of stages occur within ovary however later stages occur inside the oviduct of female.
This process occurs continuously as the stem cells are continuously replacing the lost spermatocytes.	This process is discontinuous as the starting stages happen within gestational period however the rest of stages occur later in life when the female reaches the age of puberty.
Produces sperms which are motile. They have a tail which helps them to move.	This produces eggs which are non motile.
Four sperms are formed during this process due to equal cytokinesis.	One ovum and three polar bodies are formed during this process due to unequal cytokinesis.
Sperms are formed from the epithelial lining present in seminiferous tubules.	These are formed from the epithelial lining present in ovaries.
The growth phase of spermatogonia is short lived.	The growth phase of oogonia is quite prolonging.
It has three stages which are known as spermatocytogenesis, spermatidogenesis and spermiogenesis.	It has three stages termed as follicular stage, ovulation and luteal phase.
Sperms are produced in the quantity of millions each day.	This process produces only one ovum per month.
The cell from which this process starts is primary spermatocyte.	Here, the baseline cell is primary oocyte.
The spermatocytes are nourished with the help of sertoli cells which provide nourishment.	There are no sertoli cells here, however there is a different nourishing center which is the yolk surrounding the ovum.
Spermatogenesis has no rest phase.	Oogenesis has rest phase which starts from fetus and remains till reproductive age.
Sperms are smaller in size as compared to an ovum in females.	Ovum produced is larger in size as compared to the sperms produced in males.
The DNA gets condensed in sperms and its condensation can be observed.	The DNA condensation cannot be observed in female ovum production.
Sperm is flagellated.	Ovum is spherical in shape.

Similarities between spermatogenesis and oogenesis

• Both of these processes occur within the reproductive organs of individuals (ovaries in female, testes in male).

• Both of these processes have 3 main phases in common which are multiplication where they divide from a single one into further cells, secondly there is a growth phase which is followed by the third phase of maturation where they mature into fertile sperms or eggs.
• During the phase of multiplication, the epithelial lining of both gonads (ovaries and testes) divide through the process of mitosis to give rise of a number of cells which in this case are spermatogonia and oogonia.
• During the third phase which is the growth phase, both of these cells develop a nourishment source to develop into primary oocytes in both processes.
• The stage of maturation in both of these processes involves two successive divisions including the first meiotic and the second meiotic stage which results in the development of secondary gametocytes and gametes.
• Both of these processes go through the process of meiosis when they reach the mature phase.
• Both of these processes results in haploid gametes.
• Both of these processes are necessary for the process of reproduction to take place.
• Both of these processes affect the health of individuals.
• Both are required for an individual to be called as fertile, if any individual does not have a normal gametogenesis process, then it leads to complications for both individuals similarly.

Difference between spermatogenesis and spermiogenesis

Spermiogenesis is simply the maturation of the sex cells that are being created through the process of spermatogenesis.

Conclusion

The process of spermatogenesis and oogenesis forms gametes in male and female individuals. The former process results in the formation of sperms however the later one results in the production of ovum. The fertilization or fusion of a sperm and an ovum results in the development of a zygote which divides mitotically to form an embryo.

In the process of Spermatogenesis there is the formation of haploid gametes (sperms) from a stem cell called as spermatogonium which is a diploid cell. This process takes place within seminiferous tubule which is located within testes of male individuals. This whole process takes 70 days for completion. However, Oogenesis is the process where an ovum formed. The process takes place occurs in the ovaries of a female individual. Where sperms are produced in millions per day, one ovum is produced in females per month.

These are the reproductive stages which include maturation phase, growth and then differentiation stage. The spermatogonium and oogonium divide through mitosis which results in spermatocytes and oocytes. The spermatocytes undergo division which leads to the creation of spermatids and it has only half of the genetic material present which was in the primary spermatocyte due to the process of meiosis where the genetic material gets reduce. Oocytes go through the process of mitosis, and then maturate to form ootids which differentiate further more to form an ovum. Both of these processes have similarities like they take place within gonads and they both have differences too but both of these are necessary for the process of reproduction to take place or to form an offspring.