Embryogenesis is the formation and development of the unicellular zygote, a multicellular embryo. Gametogenesis is the process in which haploid sex cells or gametes are formed, starting either from diploid or haploid precursor cells. It starts with a male and a female gamete being fertilized to form the zygote, a diploid cell. In this article, Gametogenesis and Embryogenesis are discussed in brief along with the key difference between gametogenesis and embryogenesis for NEET preparation.
What is Gametogenesis?
Gametogenesis is the process in which haploid sex cells or gametes are formed, starting either from diploid or haploid precursor cells. Cell division and maturation are the two principal processes of gametogenesis. It occurs in animals in gonads whereas it occurs in plants in gametangia.
There are also two types of gametogenesis such as oogenesis and spermatogenesis, based on the type of sex cells that are formed. In addition, oogenesis is the formation of female gametes which occurs respectively in the ovaries and archegonia. In comparison, spermatogenesis is the development of male gametes that occurs in testis and antheridia respectively.
In Addition, Both Oogenesis and Spermatogenesis Undergo Four Common Steps
Gametocytogenesis
Gametogenesis I
Gametogenesis II
Maturation
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What is Embryogenesis?
Embryogenesis is the formation and development of the unicellular zygote, a multicellular embryo. It starts with a male and a female gamete being fertilized to form the zygote, a diploid cell. In humans, the embryonic stage lasts 5 to 11 weeks approximately 58 days.
The later development phase is known as the development of fetuses. In particular, the embryogenesis' four stages include cleavage, gastrulation, neurulation, and organogenesis.
Cleavage
Cleavage is the division of cells without noticeable growth. Here the cell cluster shaped is of the same size as the zygote. The two types of cleavage are also based on the amount of yolk present in the fertilized egg, holoblastic and meroblastic cleavage. Complete cleavage occurs in holoblastic cleavage whilst only partial cleavage occurs in meroblastic cleavage. The 16-cell stage is called the morula, which undergoes the blastula stage to become a blastula.
The cell mass-produced by the cleavage initially undergoes blasting in which an outer layer of cells is created, called the trophoblast, and an inner cell mass. Then, the inner cell mass differentiates further into forming a polarized embryoblast at one end. The cavity which is formed by this polarization is known as blastocoel. Now, in mammals, this stage is called the blastocyst or blastula.
In addition, the embryoblast forms an embryonic bilaminar shell, giving rise to three germ layers. Here the embryonic disk upper layer or epiblast grows into the ectoderm. Often, the endoderm grows into the hypoblast or lower layer. After that, the development of a primitive streak starts on the epiblast floor, experiencing invagination, which leads to the migration of epiblast cells towards the primitive streak and sliding below. In addition, some hypoblast cells migrate into the endoderm, and some migrate to shape the mesoderm between the endoderm and epiblast.
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Gastrulation
Gastrulation is the single-layered blastula development process into a multilayered gastrula. Significantly, the start of gastrulation signals the beginning of the primitive streak. The basic stripe is responsible for establishing the bilateral symmetry during gastrulation. The gastrulation is therefore responsible for giving the embryo a clear head - to - tail and front-to-back orientation.
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Neurulation
Neurulation is the neural plate's transformation into the neural tube; Neurula refers to the neurulation stage the embryo has undergone. Neurulation begins with a basic node forming before the primitive streak. Here the epiblast produces the primitive node, and it causes neural plate development. The neural plate is significantly the basis of the nervous system, and it folds on to form the neural tube.
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Organogenesis
Organogenesis is the development of organs after gastrulation has ended. By cell differentiation and specialization the three germ layers, ectoderm, endoderm, and mesoderm, evolve into the body's internal organs during organogenesis.
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Difference Between Gametogenesis and Embryogenesis
Below are some points discussed to differentiate between gametogenesis and embryogenesis
FAQs on Difference Between Gametogenesis and Embryogenesis
1. What Do You Mean by Gametogenesis?
Gametogenesis is the mechanism by which the haploid cell (n) is formed by meiosis and cell differentiation from a diploid cell (2n). The males, gametogenesis is known as spermatogenesis and causes spermatozoa. In female gametogenesis is known as oogenesis and results in the ova formation.
2. What Are the Differences Between Gametogenesis and Embryogenesis?
The main difference in gametogenesis in animals and plants is that it involves the transition of cells from diploid cells to haploid cells in animals and the development of haploid gametes in plants; and gametogenesis is the creation of haploid cells in plants.
3. Why Do Females Produce Polar Bodies?
Polar bodies form because there is no uniform division of the egg cell (oocyte). This is the type of cell division that leads to haploid cells. The more cytoplasmic cell becomes a mature ovum, while the polar body usually dissolves. The primary polar body also suffers from meiosis 2 and produces two secondary polar bodies.