^ Chapter 2 - Gametogenesis: Conversion of Germ Cells into Male and Female Gameters Flashcards
Female gamete
Oocyte
Male gamete
Sperm
Zygote=
Sperm + Oocyte
Where are the gameters derived from?
Primordial germ cells (PGCs) that are formed in the epiblast during the 2nd week and that move to the wall of the yolk sac
When does the gameters move to the yolk sac toward the developing gonads?
During the 4th week
When does the gametes arrive the developing gonads?
By the 5th week
Synapsis
The process of homologous chromosomes aligning themselves with each other
Can the chromosomes be recognized with light microscope before the cell enters mitosis?
Nope
Male germ cells
Spermatocyte
Female germ cells
Primary oocyte
When does the cross overs happen?
Meiosis I
What happens in the cross overs?
Interchange of chromatid segments between paired homologous chromosomes
Chiasma
X-like structure
How many crossovers?
30-40 (1 or 2 per chromosome)
How many daughter cells does the primary oocyte give rise to?
4 daughter cells, each with 22 plus 1X chromosome
How many of the oocyte daughter cells develops into a mature gamete?
1/4 develops into a mature gamete (secondary oocyte)
How many of the oocyte daughter cells are called polar bodies?
3 of the 4 oocyte daughter cells are called polar bodies(first polar bodies?).
They recieve a little cytoplasm and degenerate during subsequent development
How many daughter cells does one spermatocyte give rise to?
4 daughter cells:
- two with 22 plus 1X chromosome
- two with 22 plus 1Y chromosome
How many of the spermatocyte daughter cells develops into mature gameters?
All 4 develop into mature gameter
Oogenesis
The process whereby oogonia differentiate into mature oocytes
What happens with the PGCs when they arrive the gonad?
They differentiate into mature oogonia
Follicular cells
single, flat, epithelial cells that originate from the surface epithelium covering the ovary
Primordial follicle =
Primary oocyte + flat epithelial cells
Diplotene stage
A resting stage during prophase that is characterized by a lacy network of chromatin
Oocyte maturation inhibitor (OMI)
- Small peptide secreted by follicular cells
- Produce the diplotene stage
- Prevents the primary oocyte to finish their meiotic division before puberty
Follicular cells secret
Oocyte maturation inhibitor (OMI)
Which stage is the longest?
The Vesicular (antral) stage
What forms the theca folliculi?
The stromal cells
Wah secrets the glycoproteins on the surface of oocyte, forming the zona pellucida?
Granulos cells and the oocyte secret glycoproteins
Theca interna
Inner secretory cells
Theca externa
Outer fibrous capsule
What induces the preovulatory growth face?
- Lutenizing hormone (LH)
When does the spermatogenesis begin?
It begins at puberty
Spermatogenesis
Includes all the events by which spermatogonian are transformed into spermatoza
Type B spermatogonia divide to form…
Primary spermatocytes
What marks the initiation of spermatogenesis?
Type A spermatogonia
What happens when the follicle stimulating hormone (FSH) binds to the Sertoli cells?
They stimulate testicular production and synthesis of intracellular androgen receptor proteins
Spermiogenesis, including:
- Formation of the acrosome
- Condensation of the nucleus
- Formation of neck, middle piece, and tail
- Shedding of most of the cytoplasm
How many days does the spermatogonium require in order to become a mature spermatozoon?
74 days
Type B spermatogonia
- Derive from primordial germ cells
- Gives rise to primary spermatocytes
What gives rise to secondary spermatocytes?
Primary spermatocytes
Secondary spermatocytes undergo meiosis II and forms?
Spermatids
When does the oogenesis begin?
Before birth
Trisomies
An extra chromosome
Monosomies
Loss of chromosomes
Nondisjunction
Homologous chromosomes spearation fails, resulting in one cell recieving too many chromosomes and 1 recieves too few
Primordial germ cells differentiate into:
When they arrive the gonads they differentiate into gonads
Where does the first polar body lie?
The first polar body lies between the zona pellucida and the cell membrane of the secondary oocyte in the perivitelline space?
