Lecture 11: Gametogenesis and Fertilization Flashcards
Primordial germ cells are progenitors
gametes
Primordial germ cells from yolk sac ______ migrate to ____ ___ which will become _____ _____.
- Endoderm
- Genital ridge
- Indifferent gonad
Intermediate mesoderm gives rise to
- Part of urogenital organs
- Leydig cells, sertoli cells, follicular cells, ovary, testis, ducts, uterus
Urogenital sinus endoderm gives rise to
- Terminal internal parts of genital organs
- Vesicular, prostate and bulbourethral glands
Mullerian ducts are also called
Paramesonephric
Mullerian ducts develop into
Fallopian tubes, uterus, cervix
Mullerian ducts in male
Disappear under the influence of anti-paramesonephric hormone
Seminiferous cords consist of
- Sertoli cells
- Primordial germ cells - stem cells for spermatogenesis and stay dormant till puberty
Two parts of the prepuberal testis
- Seminiferous cords
- Inactive interstitial cells of leydig
Cryptorchidism
- Testes fail to descend into the scrotum
- Inherited as a sex-linked autosomal recessive trait
- Cryptorchid can be unilateral (fertile) or bilateral (sterile)
Scrotal hernia
- Type of inguinal hernia
- Congenital weakness in abdominal wall
Primitive sex cells
- Spermatogonia
- Oogonia
Primitive sex cells have complete
DNA complement
How are more oogonia and spermatogonia made
Mitosis
Purpose of spermocyte and oocyte meiosis
Insure variation and provide 1/2 of the chromosome in both male (1N) and female (1N) sex cells (gametes)
Fertilization
Joining of sex cells
Fertilization creates
Zygote, which restores DNA complement (2N) and initiates cleavage
Mitosis results in formation of
2 daughter cells, each having diploid set of chromosomes, the same number of chromosomes as in the mother cell
Meiosis results in
Gametes - daughter cells that are haploid
Are gametes haploid or diploid
haploid
Two goals of meiosis
- Reduction of diploid set chromosomes into haploid in gametes
- An exchange of genetic material between make and female chromatids in prophase of meiosis I (crossing over) which results in 4 daughter cells with four different genetic makeups
Oogenesis and spermatogenesis both have (4)
- Multiplication of spermatogonia and oogonia
- Meiosis
- Extensive morphological differentiation
- Incapacity of surviving for very long if fertilization doesn’t occur
Sperm supply is
Continuously renewed
One Io spermatocytes produces
4 sperm
In sperm, initial large cell results in
small cells
Do sperm move
motile cells
Chromosome of sperm
X or Y sex chromosome
Are oocytes made after birth?
No
One Io oocyte produces
1 ovum and 2-3 polar bodies
In oocytes, initial small cell
grows into a large cell
Do oocytes move?
Nope
In mammals, chromosome for oocyte
X chromosome
Where does oogenesis occur?
Ovary
Oogonia
Prenatal mitosis and differentiation
Basic plan of oogenesis
- Oogenia
- Folliculogenesis
- Meiosis II