What does an egg cell (ovum) look like?

Ova (eggs) are produced by the ovaries—the female reproductive organs. At birth, a female possesses approximately 100,000 to 500,000 primordial follicles in each ovary. Each primordial follicle is surrounded by a single layer of primitive granulosa cells and enclosed by a basement membrane. So, what do ova actually look like? Let’s explore this further.

What Do Ova Look Like?

An ovum is a gamete (reproductive cell). It is extremely small—too minute to be seen with the naked eye. Under a microscope, the ovum appears spherical and is enveloped by the vitelline membrane—a defining structural feature. Upon entering puberty, a woman’s ovaries begin cyclically secreting estrogen and progesterone. Each month, one mature follicle develops and ruptures to release an ovum. Fertilization—i.e., union of sperm and ovum—results clinically in pregnancy. During menopause, the ovaries undergo atrophy, harden, and shrink; follicular development ceases, ovulation stops entirely, menstruation halts, and natural conception is no longer possible.

What Symptoms Occur During Ovulation?

1. Light Spotting

Slight uterine bleeding may occur before or after ovulation due to fluctuations in circulating estrogen levels—termed “ovulatory bleeding.” Minimal spotting during this period is generally considered normal. However, abnormal uterine bleeding may also stem from gynecologic conditions such as menstrual irregularities, cervical polyps, cervical ectropion (formerly termed “cervical erosion”), or cervical cancer. Therefore, if ovulatory bleeding persists for an extended duration or involves heavy flow, prompt medical evaluation—including comprehensive diagnostic testing—is strongly advised.

2. Basal Body Temperature Shifts

In healthy, reproductively active women, a mature ovum is released from the ovary each month. Basal body temperature (BBT) follows a biphasic pattern: a lower-temperature phase precedes ovulation, followed by a higher-temperature phase post-ovulation. Typically, pre-ovulatory BBT ranges between 36.2°C and 36.5°C; following ovulation, it rises by approximately 0.3–0.5°C. This elevation reflects increased progesterone secretion after ovulation and serves as a physiological indicator that ovulation has occurred.

The above provides an overview of the morphology of human ova. Structurally, a mature follicle releases an ovum measuring roughly 20 micrometers in diameter, encased by multiple layers of granulosa cells. The outermost layer of these cells radiates outward from the oocyte surface—hence its name, the “corona radiata.” Moving inward, successive layers include the zona pellucida, perivitelline space, and vitelline membrane. We hope this information proves helpful.