MCAT Content / Reproductive System / Ovum And Sperm

Ovum and sperm

Topic: Reproductive System

Ovum (female gamete) and sperm (male gamete) are necessary for the reproduction process but they differ in formation, morphology, and relative contribution to the next generation.

Ovum and sperm play an essential role in the reproduction process, where the participation of both the opposite gametes is equally significant and necessary. However, they differ in terms of the formation, morphology, and their relative contribution to the next generation.

The formation of egg and sperm cells varies. Spermatogonium renews its population by mitosis throughout life while oogonium stops renewing its population sometime before birth. During meiosis, the primary and secondary oocytes arrest in prophase I and metaphase II, respectively, while primary and secondary spermatocytes directly go through meiotic cell division to produce haploid cells. Between the secondary spermatocyte and the sperm, there’s the spermatid. After secondary oocyte, ovum develops.

Sperm and ovum also differ in characteristics. Spermatids undergo a morphological change, known as spermiogenesis, which then becomes spermatozoa. There is no corresponding stage observed in females. However, ovum, rounded-sphere, non-motile egg, is larger compared to the sperm cell. On the contrary, sperm cell, a motile flagellum, is differentiated into the head, neck, middle piece and tail and the smallest cell in the male body. The middle piece of the sperm contains many mitochondria, to generate ATP for motility.

Furthermore, they also differ in their relative contribution to the next generation. Sperm only contributes to DNA (the egg actively destroys sperm mitochondria) while egg contributes to the production of DNA, mitochondria, organelles and epigenetic inheritance.


Practice Questions

Khan Academy

MCAT Official Prep (AAMC)

Biology Question Pack, Vol. 1 Passage 9 Question 56

Practice Exam 2 B/B Section Passage 9 Question 46

Key Points

• Ovum and sperm play an essential role in the reproduction process but differ in terms of the formation, morphology, and relative contribution to the next generation.

• The formation during developmental stages of gametogenesis, specifically in meiosis, vary in male and female.

• Sperm is the male gamete which is long, motile, flagellated cell and is differentiated into head, neck, middle piece and tail, though they are comparatively smaller in size; the ovum is the female gamete, where the cells are rounded spheres and non-motile, though not differentiated into different parts, and the cells are larger in comparison to the sperm cell.

• Ovum and sperm differ in their relative contribution to the next generation, such that sperm only contributes to DNA. In contrast, egg contributes to the production of DNA, epigenetics, and other organelles.


Key Terms

spermatozoa: the mature motile male sex cell of an animal or human

ovum: the female reproductive cell

sperm: the male reproductive cell

gametes: sex cells

meiosis: cell division of a diploid cell into four haploid cells, which develop to produce gametes

mitosis: the division of a cell nucleus in which the genome is copied and separated into two identical halves. It is normally followed by cell division

oocyte: a cell that develops into an egg or ovum; a female gametocyte

oogonium: an immature female reproductive cell that gives rise to primary oocytes by mitosis

spermatid: the haploid male gametid that results from the division of secondary spermatocytes

spermiogenesis: the final stage of spermatogenesis, which sees the maturation of spermatids into mature spermatozoa

spermatozoa: the mature motile male sex cell of an animal

haploid: half the number of chromosomes



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