Fundamentals 1 Flashcards
Sex determination Gene
SRY gene
45 XO
Turners syndrome - Female
47 XXY
Klinefelters Syn -Male
Gene Codes for Testis
SOX 9
Gene Codes for Ovary
RSPO 1 and WNT 4
Best Investigation for Sex determination and to detect defect in chromosomal number
Karyotyping
Defect in Chromosomal Number
Aneuploidy - Triploidy, Trisomy, Monosomy.
Most commonly used method for sex determination
Looking at external genitalia
Exception- Ambigous Genitalia
Barr Bodies Method
Method to detect sex. Number of chromosome X-1 normal female 1 normal male 0 Turner 0 klinefelters 1 Cant diff btw them
Origin of Urogenital System
Mostly Mesodermal
Excp- Urogenital Sinus- Endodermal
Origin of Urogenital Ridge
Intermediate Mesoderm- @ 5 weeks
Derivatives of Urogenital Ridge
1) Gonads and Ducts
2) Renal System
External Genitalia derived from
Dorsosomatic part of Lateral Plate Mesoderm
Germ Cells are derived from
Epiblast- MIgrate to Yolk sac @ 3 Wks and Genital Ridge @ 5 wks
Gonads are derived from
Genital Ridge
Bipotential till 6 wks
Differentiation of Gonads depends on
SRY Gene present on Short Arm of Y chromosome
if + nt its male- XY
If - nt its female- XX
Medulla of Genital Ridge give rise to
Testis @ 7 wks
Cortex of Genital ridge gives rise to
Ovary @ 8 wks
Reason for Streak Ovaries in Turners
Absence of second X chromosome
Type of gonad in Klinefelter and why.?
Testis coz of Presence of Y chromosome
Spermatogonia to Primary Spermatocyte what division.?
Mitosis
Primary to Secondary Spermatocyte what division.?
Meiosis 1- Reduction division
46XY to 23 X and 23 Y
Primary to Secondary Spermatocyte what division.?
Meiosis 1- Reduction division
46XY to 23 XY and 23 XY
Secondary Spermatocyte to Spermatids.. what Division.?
Meiosis 2
What is Spermiogenesis.?
What is Spermatogenesis.?
Spermatogenesis- Spermatogonia to Sperms
Spermiogenesis-Transformation of Spermatids to sperm.
1 Spermatocyte Gives rise to how many Sperms.?
1 Spermatogonia- 16 Primary Spermatocyte
1 Primary Spermatocyte - 4 Sperms
so 16*4=64 sperms
Time Taken For Spermatogenesis
72-74 Days
Per day Avg- 100 million sperms
Time Taken for Spermiogenesis
12-14 Days
No Mitosis/Meiosis
9+2 Arrangement
Sperms lack Endoplasmic Reticulum esp RER
Where does Sperm attain Motility and Maturity.?
Caudal end of Epididymis
Genes that codes for Motility of Sperms
CATSPER
Ion for motility of Sperms
Ca++
Ion for motility of Sperms
Ca++
Sperms remain Motile in Female for.?
12 Hrs
Time taken for Sperm to reach FT.?
30 mins
Where is GNRH synthesised.?
Arcuate Nucleus of Hypothalamus
Protein for Pulsatility of GNRH
KISSPEPTIN and KISS-IR Receptor
LH acts on
Leydig cells - produces Testosterone
LH acts on
Leydig cells - produces Testosterone
FSH acts on
Sertoli Cells- Produces Inhibin B ( -ve FB on FSH) and ABP- Androgen binding Protein.
Action of Testosterone
Negative FB on LH and GNRH
Also Responsible for Spermatogenesis along with FSH and LH.
First stimulus req to release Testosterone
HCG from Leydig cells
Blood - Testis Barrier
Sertoli cells
Outside- Leydig Cells
When does Spermatogenesis occur.?
Puberty
When does Oogenesis Occur.?
in IUL
1) Oogonia to Primary oocyte.?
2) Primary to Secondary oocyte.?
1) Mitosis
2) Meiosis 1- arrested in Diplotene stage of Prophase.
What is Dictyate state.?
Arrested Primary Oocyte in Meiosis 1 - Diplotene Stage of prophase.
Absent in Spermatogenesis
What is Primordial Follicle
Primary Oocyte surrounded by Follicular cells ( Granulosa and Theca)
When does Meiosis 1 Resume.?
At puberty coz of LH surge
What is Ovulation.?
Primary oocyte to Secondary oocyte plus polar body(Perivitelline Space).
Secondary oocyte is arrested in.?
Metaphase.
What does Secondary Oocyte give rise to .?
Female Pronucleus (ova) and second polar body at the time of fertilization.
Time Btw LH surge and Ovulation
32-36 Hrs or 24-36 Hrs
When is 1st and 2nd polar Body released.?
1st at time of Ovulation
2nd at time of Fertilisation
Size of Follicle before Ovulation.?
18-20 mm
Fertilizable span of Ovum
12-24 hrs
Sperm- 48-72 hrs
Oogonia formed at.?
9 wks
Primary oocyte formed at.?
12-16 wks
Follicle formation starts at.? Completed by.?
15-20 wks
22-24 wks
max number of follicles seen at.?
20 wks - 5-6 million
Number of Follicles at birth.?
1-2 Million
Number of Follicles at Puberty.?
4-5 Lakhs
Initial Recruitment or atresia of Follicles is.?
Hormone Independant.
Testosterone Production begins at and maximum at.?
Begins at 7-8 Wks
Max at 15 weeks and then its low till puberty.
Rate of testosterone prod in adult male.?
5-7 mg / day
free T level- 0.5 to 3.1%
Testosterone converted to estrogen by.?
Aromatase
Amount of E2 prod in males per day.?
50 mcg / day
20% in testis
rest in Adipose tissue
Role of Estrogen in Males
Inc Bone Density
Closure of Epiphyseal plate of Long Bones
Maintenance of Body fat
Sexual Function
Excess Estrogen in Males causes
Gynaecomastia
Hormone responsible for Conversion of Testosterone to DHT
5-alpha reductase
Most Potent Androgen
DHT
Ratio of Test : DHT
10/15:1
Meiosis 1 is also called as
Transition Meiosis