Learn More About Eggs

In sexual reproduction, the egg is the first stage of the life of an individual. It's a cell, after fertilization of an egg (female gamete) (that is to say the merger with a male gamete: sperm for animals or pollen to plants). This cell grows by successive divisions to form the embryo.

The original and still in common parlance, they called the whole egg formed the organization that develops before birth and its protective environment. Indeed, in birds, reptiles and monotremes, the female surrounds the egg shell, hard or flexible depending on the species. It also gives the name to an unfertilized egg.
The egg is a single cell, which is distinguished from others by its size, not very often microscopic.
Animals that lay eggs before they hatch are called oviparous. In other animals, the egg hatches in the matrix, before spawning, this is called ovoviviparous.

Oligolécithe (oligos, few): Egg yolk average level. Segmentation is subequal.
Centrolécithe: egg whose yolk is concentrated in the center. This egg is found in arthropods. Their nuclei are slightly eccentric due to the presence of yolk in the form of small granules in the cytoplasm. The size of these eggs is approximately 100 nm in diameter.
Hétérolécithe (heteros, other): This term refers to eggs with the yolk is distributed unevenly, causing an unequal segmentation (in amphibians).
Télolécithe (τέλος telos, end, aim, whole, complete): Egg characterized by a considerable amount of yolk located at one pole. Segmentation is only the territory located near the animal pole. This segmentation produces a blastula-shaped disc (blastodisc), floating on the yolk reserves (the "yellow" of the egg).
Alécithe (a private deprivation, denial): Egg characterized by a low volume of yolk. The blastomeres resulting from the segmentation (equal) will be substantially equal.
Egg shells

Birds are the only animals that lay eggs spotted. Several functions have been attributed to this pigmentation, such as camouflage in the eyes of predators. Toutetefois, we encounter the same pigmentation in birds whose eggs are completely hidden in the nest.

According to Andrew GoSL and colleagues (Institute for Ornithology Edward Grey, Oxford), these tasks play a role in the robustness of the shells. Indeed, by studying populations of great tits in areas where resources vary in calcium, they have established a relationship between tasks and the thickness of the eggshell. Thus, the thickness is generally lower in places showing the tasks to darker, but the eggs laid in environments rich in calcium are less stained than those areas where this resource is not available.

These tasks consist of protoporphyrin, a molecule produced during the synthesis of heme (a component of hemoglobin). However, this molecule could, to some extent, play a role in the structure of the shell. Indeed, the infrared protoporphyrin returns, avoiding water loss, it also shows a structure close to the solid lubricant s (as graphite), allowing for better shock absorption.

For birds, these tasks could also give an indication of the degree of fragility of the eggs, especially by exposing sensitive areas.

From the website: Wikipédia

Posted in: Canaries