The Yolk Of An Animal Egg Has What Type Of Analog In Angiosperms?

Egg jail cell or ovum, also known every bit female gamete is formed by the process of oogenesis in female organisms.
They are produced by follicle cells present in the ovaries.
Egg cells are released in the secondary oocyte stage past the process called ovulation.
They are haploid in nature and are obtained by meiosis.
Ovum is the largest cell in human being beings. They are larger than sperms.

Construction:

Ovum is circular (nearly spherical) and is non-motile as it is devoid of a tail.
Information technology consists of a fundamental nucleus, cytoplasm and the prison cell membrane.
Nucleus consists of genetic material which once fertilized by sperm, helps to determine the characteristics of the off jump.
The cytoplasm surrounding the nucleus is called yolk or ooplasm, which consists of nutrients required for the developing embryo.
The peripheral layer of ooplasm is known equally cortex which consists of many microvilli and cortical granules.
An unfertilized egg in birds and reptiles also consists of outer transparent albumen surrounding the yolk.
In telolecithal and mesolecithal eggs, the upper black pigmented one-half the cell containing a nucleus is called animal pole and the lower whiter one-half containing yolk is called a vegetal pole.

The egg cell is surrounded by a thin double layered membrane.
The inner layer is chosen vitelline membraneand the outer layer is chosen zona pellucida.
The space between the 2 layers is called a pre-vitelline membrane.
Eggs of birds and reptiles are also covered externally by a difficult calcareous shell.
On the footing of amount and distribution of yolk, eggs are of various types.

1. On the footing of amount of yolk present, eggs are of following types:

Alecithal egg:
- The ovum consists of most no yolk in it.
- Animals like human beings, marsupials and eutherian animals produce such eggs.
Microlecithal egg:
- Such eggs consist of pocket-size amount of yolk in them.
- They are also chosen oligolecithal eggs.
- e.one thousand. eggs produced by sea urchin, Branchiostoma
Mesolecithal egg:
- There is moderate amount of yolk present in it.
- east.g. lungfishes, frogs, toads etc.
Megalechital or Macrolecithal or Polylecithal egg:
- They contain huge amount of yolk in them.
- eastward.k. sharks, bony fishes, reptiles, birds, insects and prototherians

2. On the ground of distribution of yolk, eggs are of post-obit types:

Homolecithal or Isolecithal egg:
- Yolk is evenly or uniformly distributed inside an egg.
- Such distribution is found in alecithal and microlecithal eggs.
Telolecithal egg:
- In such eggs, most of the yolk lies nigh the vegetal pole.
- The cytoplasm and nucleus well-nigh the animal pole.
- Such distribution is observed in mesolecithal and macrolecithal eggs.
- In craven, the huge amount of yolk occupies the entire ovum but the cytoplasm and nucleus lie in the animal pole. This status may be referred to every bit highly telolecithal.
Centrolecithal egg:
- In such eggs, yolk is centrally placed and surrounded by thin cytoplasm.
- Some insects have centrolecithal eggs.