16 Questions
What is the term for the loss of a segment of a chromosome?
Deletion
At what week of human embryo development do the primordial gonadal cells (PGC) migrate from the yolk sac to the genital ridges?
4 weeks
What is the result of the activation of the SRY gene in the development of the male gonad?
Formation of the testis
What is the process by which immature oocytes are distributed throughout the ovary in follicles?
Folliculogenesis
How many follicles are present in each human ovary?
200,000 to 400,000
What is the location of primordial follicles in the ovary?
In the stroma (near the outside)
What is the result of the differentiation of primordial germ cells into an unfertilized egg?
Proliferation and growth in size
What is the syndrome caused by the deletion of a segment of chromosome 5?
Cri-du-chat syndrome
What is the process by which the number of chromosomes is reduced in gametogenesis?
Meiosis
What is the term for the union of male and female gametes?
Zygote
What is the term for the process of converting germ cells into male and female gametes?
Gametogenesis
In which layer of the yolk sac do germ cells originate from?
Endodermal layer
What is the term for the phenomenon where a part of a chromosome breaks off and attaches to another?
Translocation
What is the result of non-disjunction during meiosis?
Both trisomy and monosomy
How many phases are there in gametogenesis?
Four
What is the haploid number of chromosomes in a gamete?
23
Study Notes
Gametogenesis
- Gametogenesis is the conversion of germ cells into male and female gametes, resulting in the formation of sperm and oocytes
- It involves four phases: origin and migration of germ cells, increase in number of germ cells by mitosis, reduction in chromosomal number by meiosis, and structural and functional maturation of eggs and sperm
Oogenesis
- Oogenesis is the process of formation of female gametes (oocytes)
- Immature oocytes are distributed throughout the ovary in follicles, with a total of 200,000 to 400,000 follicles present in each human ovary
- Each follicle contains a single oogonium
- Few oogonia reach maturity, with typically fewer than 400 oocytes maturing and being released by ovulation
- Location of oocyte depends on its maturity, with primordial follicles most prevalent in the stroma (near the outside) and oocytes becoming more centrally located as they mature
- Primordial germ cells migrate to the ovary during fetal and embryonic development
- Differentiation of primordial germ cell into an unfertilized egg requires proliferation and growth in size
Mitosis and Meiosis
- Mitosis is a process where a cell divides into two daughter cells that are genetically identical to the parent cell
- Meiosis occurs in germ cells and involves two cell divisions, Meiosis I and Meiosis II, to produce gametes
- Meiosis I reduces the number of chromosomes by half, and Meiosis II separates the sister chromatids
Chromosomal Abnormalities
- Numerical chromosomal abnormalities occur due to non-disjunction, leading to trisomy (three copies of a chromosome) or monosomy (one copy of a chromosome)
- Structural chromosomal abnormalities do not affect the total chromosome number but have serious consequences, such as translocation (where a part of a chromosome breaks off and is attached to another) or deletion (where a segment of a chromosome is lost)
- Deletion can lead to syndromes, such as Cri-du-chat syndrome (which occurs at chromosome 5)
Learn about the process of gametogenesis, including oogenesis and spermatogenesis, and understand the differences between them. This quiz covers the phases of oogenesis and the conversion of germ cells into male and female gametes.
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