Reproduction Flashcards
Two hormones that are created by PG
LH and FSH
The release of FSH and LH is controlled by which hormone?
Gonadotrophin releasing hormone (GnRH)
Where is GnRH released fro
‘Hypothalamus
What hormone do the ovaries secrete
Oestrogen and progesterone
Where does the gamete take place in male
Testis
Where does the gamete take place in female
Ovary
3 main steps involved in gametogenesis
Proliferation of germ cells
Meiosis
Maturation
What does primary sex organs or gonads do?
Make haploid gametes and produce sex hormones
What do accessory sex organs do?
A. Carry the gametes
B. Bring out fertilisation
C. Protect the zygote
The primary sex organs in the male
Testes
Where is testes
In a skin sac called scrotal sac/ scrotum
Why the location of testes are important
It is important for spermatogenesis to occur at a temperature slightly lower than body temperature
What are the accessory sex glands
1.Seminal vesicles
2.Prostate
3.Bulbourethral gland
Seminal vesicles
Fructose, prostaglandin, provides 60% of semen volume and also secretes fibrinogen
Prostate
Secretes alkaline fluid, citric acid , provides clotting enzymes and PSA 20% volume
Bulbourethral gland
Produce mucus like substance
Where do testis develop from
Develop in the abdomen and move into the scrotum before birth
How many seminiferous tubules are present in each testis
400-600
What are testes mostly made of
Seminiferous tubules and produce 100million spermatozoa a day since puberty to death
The walls of the tubules in testis contain
Primitive germ cells that mature and move to the lumen
Where do tubules drain into?
Drain in the head of the epididymis and into the vas deferens
Name the two main cells in testes
1.Lyedig or interstital cells
2.sertoli cells
Function and location of leydig cells
Between the tubules and their main function is to produce testosterone by LH
Function of Sertoli cells
Support cells in the tubules and make regulators for spermatogenesis and are rich in glycogen
How many chromosomes sperm have
23 chromosomes
Total time for spermatogenesis
74 days - FSH has an important role here
During adolescence what happens to primitive germ cells
Turn into the basal lamina which mature into primary spermatocytes
The process from primary to secondary spermatocytes
Is done by meiosis and then spermatids
Are spermatids haploid or diploid
Haploid - 23 chromosomes
What spermatids mature into
Spermatozoa(sperm)
What is the estimated number of spermatids formed from a single spermatogonium
512
What is acrosome?
Known as the enzymatic knife located on the anterior part of the sperm nucleus.
Are spermatozoa fully mobile when leaving testes
No, they continue their maturation and acquire motility during their passage through the epididymis
What is acquired in epididymis
Forward motility and involves protein activation
What is the primary reproductive organ of the female
Ovaries, which produce ova (egg cell) and sex hormones
What are the accessory organs in female?
1) fallopian or uterine tubes
2)uterus
3)vagina
4) vulva
What happens to ova at birth
Arrested in prophase 1st meiotic division
Where ovaries are located
Small organs that are located on each side of the uterus
Do ovaries produce haploid or diploid chromosomes
Ovaries produce haploid ova and secrete sex hormones
Female sex hormones
Oestrogen and progesterone
What each follicle contain
Each follicle contain s primary oocyte ready to develop into egg cells
What is primary oocyte surrounded by
Follicular cells
What are secondary sexual characters controlled by oestrogen
- Finner body hair
2.wider pelvis
3.smaller body size - Development of breasts
- Extra subcutaneous fat
What is progesterone for
1.Stimulating uterine changes during the menstrual cycle
2. Affecting the breast tissue development
What makes oestrogen
Granulosa cells and theca interna
Explain what happens on the 14th day of the cycle
The follicle ruptures, releasing the ovum (secondary oocyte) this is called ovulation. The first meiosis division is completed just before ovulation
What is ovum known as
Secondary oocyte
When is the 1st meiotic division is completed
Just before ovulation.
When is secondary oocyte begins the second meiotic division
Immediately, but this division stops at metaphase and is completed only when spear enters the oocyte
Where fallopian tubes extend from
Extends from the uterus to the ovaries
Where is fimbrae
End of fallopian tubes
Role of fimbrae
Catch the egg as it leaves the ovary during ovulation
Where fertilisation occur
Where zygote forms
Description and location of uterus
A thick muscular sac at the front of the pelvic cavity behind the urinary bladder
Why in a non-pregnant women uterus is small
Because during, the uterus is stretched to hold the baby and its membranes. 5-8 cm long
How baby is pushed out?
Contraction of the smooth muscle in the wall of the uterus at the end of the pregnancy
Describe vagina
Vagina is a muscular tube leading from the vaginal orifice to the uterus
What does vagina carry
Uterine secretions and is the birth canal for the foetus
Location of vulva
External organs of the female which are found surrounding the openings of the urethra and the vagina
What is included in vulva
Clitoris,Labia Minora, labia majora and the vestibule (orifice)
When human fertilisation occurs
Male genetic material from a spermatozoon fuses with the ovum
Where sperm and ovum fuse
In upper third of uterine tube (ampulla)
Where sperm deposited
Near to the cervix
What will happen after 30-60 min after intercourse
Sperm arrives at uterus /uterine tube junction
What gradient sperm follows
Chemotactic
How long oocyte is available for
12-24 hours
What happens when sperm is attracted to the ovum
Bind to the zona pellucida
What happens when sperm bonded to zona pellucida
Release acrosomal enzymes, penetrate the ZP, and fuse with the membrane of the ovum, releasing the sperm nucleus into its cytoplasm
Describe the steps of fertilisation
1.Chemoattraction of the sperm to the ovum by substances produced by the ovum
Second step of fertilisation
Adherence to the zona pellucida , a gel-like membranous structure surrounding the ovum
Third step of fertilisation
Penetration of the zona pellucida and the acrosome reaction (with the help of Ca2+)
4th step of fertilisation
Adherence of the sperm head to the cell membrane of the ovum, with breakdown of the area of fusion and release of the sperm nucleus into the cytoplasm of the ovum
Explain the fertilisation events
1.Sperm contact oocyte membrane will fertilise the egg
2.The contact will trigger 2nd meiotic division
3.secondary oocyte becomes an ovum
4. Sperm nucleus engulfed by egg membrane
5. Ovum is a short-lived cell as haploid sperm nucleus quickly fuses with haploid ovum
Where does sperm nucleus swells
Inside the ovum
What happens to chromosomes in the pronuclei
They replicate as both pronuclei move to centre of the ovum and a Mitotic spindle forms
What happens when M and F chromosomes line up
New structure formed - a diploid 2n zygote
What are the 2 phases that human zygote undergoes until considered an embryo
- Pre-implantation development
2.post-implantation development
Cell divide approx . Once every 12 hours until a ball of cells is formed. What is the name?
Morula
What morula
And how many cell is contained in one ball
- 64 cells
Nourished by secretion produce by the epithelium of uterine tubes.
What happens after 3-4 days after ovulation
Morula enters uterus
What is morula size constrained by
Zona pellucida
What cells are on the morula
Tori potent cells which can form all the cell types in a body, plus the extraembryonic or placental, cells
What is special about morula
Have no predetermined destiny and could differentiate into any cell type
Fluid forms inside morula
Uterine fluid which turns into blastocyst
Hollow sphere of cells or blastocyst consists of :
1) clump of cells inside sphere , called inner mass
2) a flattened ring of outer cells, called the trophoblast
Name given to fluid-filled cavity
Blastocoele
What is decidua
Endometrial cells at point of contact thicken or hypertrophy
Role of trophoblast cells in implantation
Invade decidua and release enzymes, which causes blastocyst to bore its way into deeper tissues
When is implantation completed
- 10 days after fertilisation (day 24 of the women’s cycle)
