Complete Guide on 15 Parts of a Egg: Names, Functions & Diagram

Eggs have been a special food item for thousands of years. Evidence of egg consumption dates back to ancient civilizations such as the Greeks and Egyptians. They are delicious. Eggs are a great protein, vitamin D, choline, and selenium source. This makes them a nutritious and accessible ingredient in kitchens worldwide. Each part of the egg serves a specific purpose. The yolk contains nutrients and fat. The white is rich in protein. The shell protects the egg and helps to keep it fresh. The interrelation of egg parts is itself a mystery.

Cooking with eggs is incredibly versatile. You can use classic techniques like boiling and frying or modern methods like sous vide cooking. Eggs offer endless possibilities in the kitchen, no matter your skill level. They can be incorporated into numerous dishes, resulting in tasty and satisfying meals.

From ancient times to the modern day, eggs have maintained their status as a staple food item, valued for their versatility and nutritional value. So why not try cracking open eggs and exploring the endless possibilities in the culinary world?

Parts of an Egg Diagram

Parts of a Egg, Names & Diagram

Egg Parts Names

  • Eggshell
  • Outer & Inner Shell Membrane
  • Chalaza
  • Exterior Albumen
  • Middle Albumen
  • Vitelline Membrane
  • Nucleus of Pander
  • Germinal Disk (blastoderm)
  • Yellow Yolk
  • White Yolk
  • Internal Albumen
  • Air Cell
  • Cuticle or Bloom

Parts of an Egg & their Functions


Eggshells are one of the animal kingdom’s most intriguing and unique natural structures. Their exterior is composed almost entirely of calcium carbonate, which gives them their characteristic strength and durability.

What sets eggshells apart, however, are the up to 17,000 tiny pores that dot their surface. These pores exchange air and moisture, creating a perfect environment for the developing embryo.

The bloom or cuticle covering the shell also acts as a natural barrier. It protects the egg from dust and germs. Together, these features make eggshells a true wonder of nature. They are a testament to the intricate design of the natural world.

Outer & Inner Shell Membrane

The egg is a unique natural wonder with remarkable complexity and sophistication that showcases nature’s ingenuity. The egg’s specialized membranes, primarily keratin, are designed to defend against bacterial invasion. They ensure the safety of the developing embryo inside.

As the egg cools, these membranes separate, creating an air cell. This air cell allows the embryo to breathe and nurtures its growth. This intricate design showcases the unparalleled ingenuity of nature’s creations. It also highlights the awe-inspiring power and complexity of the natural world.


One of the most interesting features is the chalazae. They are opaque bands of egg white that act like anchors, keeping the yolk centered within the egg.

These remarkable structures connect the yolk’s casing to the eggshell’s membrane. They provide crucial support and protection during the early stages of development.

The chalazae’s visibility varies with the egg’s freshness, showcasing the complexity and sophistication of nature’s engineering. The egg’s intricate design and functions are a testament to the incredible ingenuity of the natural world, inspiring awe and wonder in all who encounter it.

Exterior Albumen

One of these features is the outer thin albumen. It is a thin layer of fluid that sits next to the eggshell membrane. This seemingly unremarkable layer, however, plays a critical role in protecting the developing embryo. It acts as a barrier against harmful bacteria and other potential threats.

Despite its simplicity, the thin outer albumen is essential to the egg’s intricate design. It showcases the remarkable ingenuity and sophistication of nature’s creations.

Middle Albumen

The chalaziferous layer of an egg is not unique in its function but also in its composition. Unlike other parts of the egg, such as the shell or yolk, the chalaziferous layer has a highly fibrous and dense structure. This structure provides exceptional strength and resilience.

The chalaziferous layer’s distinctive composition allows it to withstand the physical stresses and movements during incubation. It also prevents the yolk from settling or rotating within the egg.

Additionally, the chalaziferous layer contains proteins and riboflavin uniquely suited to support the embryo’s growth and development. These essential nutrients are present in a highly concentrated form.

Overall, the chalaziferous layer’s ability to maintain the egg’s structural integrity and support embryonic development makes it a truly remarkable and unique egg feature.

Vitelline Membrane

The transparent membrane that encases the egg yolk maintains its integrity and prevents mottling. Mottling occurs when the yolk’s surface appears speckled with light blotches or patches, which can be unappealing to consumers.

Therefore, the durability and strength of the vitelline membrane play a crucial role in ensuring the visual appeal and quality of the egg.

Nucleus of Pander

The egg also contains a small white yolk plug, which is purely composed of nutrients and has no developmental significance.

This plug serves as a reserve of food for the developing embryo. It plays a minor role in the overall architecture of the egg. Its composition and location are unique to each egg. It can be used to identify and classify different types of eggs.

Germinal Disk (Blastoderm)

The blastodisc is a small, round, white patch on the yolk’s surface, measuring 2 and 3 mm in diameter. This area is the sperm’s entry point and contains the egg’s nucleus.

The embryo develops from the blastodisc and begins forming blood vessels that penetrate the yolk, nourishing its growth.

Yellow Yolk

The egg yolk is a rich source of vitamins, minerals, and nutrients. It provides nearly half of the egg’s protein, fat, and cholesterol. The yolk has lower water and higher protein content than egg white. It also contains most of the egg’s vitamins and minerals, including iron, vitamin A, vitamin D, phosphorus, calcium, thiamine, and riboflavin.

Lecithin, a potent emulsifier, is also present in the yolk. The color of the yolk can range from a subtle yellow to a magnificent deep orange, depending on the breed and diet of the hen.

White Yolk

The latebra is a fascinating enigma in the world of egg biology. This intriguing feature of the egg yolk appears as a bright white spot at the center of the yolk due to its lower fat content. Its function is not yet fully understood.

However, the latebra is thought to play a pivotal role in forming the layers surrounding it. Its unique appearance has caught the attention of researchers who have studied it using Magnetic Resonance Imaging.

Internal Albumen

Imagine holding an egg in your hand and observing its structure. You would notice a thin, transparent membrane coating the yolk, and inside this membrane, there is a compact, fibrous layer known as the thick inner white.

This layer, composed mainly of albumen, surrounds the yolk and provides it with essential nutrients. The most remarkable feature of this layer is the chalazae. They are two opposing twisted strands of protein that emerge from the top and bottom of the egg.

They converge at the yolk’s center. These chalazae act as a natural suspension system. They hold the yolk in place and prevent it from shifting around within the eggshell.

Air Cell

The most remarkable feature of this layer is the chalazae. They are two opposing twisted strands of protein that emerge from the top and bottom of the egg. They converge at the yolk’s center.

These chalazae act as a natural suspension system. They hold the yolk in place and prevent it from shifting around within the eggshell. This natural process provides an ideal environment for the growing embryo.

Interestingly, the air cell size can be used to estimate the egg’s freshness. The larger the air cell, the older the egg, so storing eggs properly is essential to maintain their quality and prevent the growth of harmful bacteria.

Cuticle or Bloom

The eggshell is an incredible work of nature, produced by the shell gland of the oviduct in hens. It features a protective coating known as the cuticle or bloom. This coating is crucial in reducing moisture loss and preventing bacterial penetration by sealing the pores.

Unfortunately, the cleaning process used to prepare table eggs often removes a substantial amount of the cuticle. This can compromise the egg’s integrity and pose potential health risks.

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