Origins of body forms 1 Flashcards
Gametogenesis and ovulation
Define gametogenesis
Is the formation of male and female gametes by spermatogenesis and oogenesis
What is spermatogenesis
Formation of complete motile spermatozoa from primordial germ cells (spermatogonia)
Where does spermatogenesis occur
In seminiferous tubule of testis
When does spermatogenesis start and end
Starts at puberty and ends at old age
What is the nature of the spermatogonia cell
Diploid (46)
What results in the growth of spermatogonia (44xy), what is the nature of the cell
Primary spermatocytes, diploid (46)
List the steps of primary spermatocyte maturation
1ry spermatocyte (diploid, 46)
|
| Meiosis 1
|
v
2ry spermatocyte (haploid, 23)
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| Meiosis 2
|
v
Spermatid (haploid, 23)
What are spermaids
Immobile, haploid sperm cells
What is the process of transforming a spermatid to a spermatozoa
SperMIOgenesis
How many spermatozoans are produced from 1 primordial germ cell
4
What is the normal sperm count for a fertile male
100 million/ml or 300-500 million/ ejaculate
What is oogenesis
Process of differentiation of a mature oocyte from primordial germ cells (oogenia)
When does oogenesis begin
3rd month of intrauterine life till birth
-pause-
then after puberty at each ovarian cycle and after fertilization
When does oogenesis end
At menopause
What are the 2 prenatal stages
Proliferation and growth
What are the 3 postnatal maturation stages
1st maturation division and 2nd maturation division (at fertilization)
What is the nature of oocytes at birth
All oocytes are primary oocytes (diploid, 46)
What happens to 1ry oocyte at puberty/ ovarian cycle
1ry oocyte undergoes meiosis 1 and becomes 2ry oocyte (haploid, 23) + polar body
What happens to 2ry oocyte if fertilization occurs
2ry oocyte undergoes meiosis 2 and becomes mature ovum (haploid, 23) + 2nd polar body
what may occur die to long meiotic division process
High frequency of meiotic error (ex: trisomy 21)
What occurs during menstruation in terms of ovarian follicles
Graafian follicle ruptures, releasing 2ry oocyte
Define ovulation
Rupture of graafian follicle and discharge of 2ry oocyte
What is the onset of ovulation
14th day
What happens to the ruptured graafian follicle if 2ry oocyte is fertilized
Follicle is luteinized under the effect of LH becoming a corpus luteum
What is the function of corpus luteum
Production of progesterone in the first 3-4 months of pregnancy to increase the lining thickness of the uterus till placenta is formed
What happens to the ruptured graafian follicle if 2ry oocyte is not fertilized
It undergoes fibrosis
