Human Reproduction Gametogensis Flashcards
What is spermatogenesis and when can it occur
In testis the immature male germ cell (spermatogonia) produce sperms by spermatogenesis that begins at puberty
How does spermatogonia multiply
The spermatogonia present on the inside wall of the seminiferous tubules undergoes mitotic division and increases in number
Spermatogonium ploidy and chromosome no
Each spermatogonium is diploid in nature and has 46 chromosomes
Define 1° spermatocytes
Some of the spermatogonia called primary spermatocytes periodically undergo meiosis
What is spermiogenesis
The spermatids are transformed into spermatozoa (sperms) by the process called spermiogenesis
What happens after spermiogenesis
The sperm heads become embedded in the sertoli cells and are finally released from the seminiferous tubules by the process called spermiation
What hormones is the primary cause of spermatogenesis
Spermatogenesis starts at the age of puberty due to significant rise in the gonadotropin releasing hormone (GnRH) which is a hypothalamic hormone
Who relases the GnRH hormone
The hypothalamus
Who does GnRH act as
What does that do
The increased levels of GnRH then acts as the anterior pituitary gland and stimulates secretion of two gonadotropins
Luetenising hormone (LH)
Follicle stimulating hormone (FSH)
How does LH work and what does it do
LH acts as the leydig cells and stimulates synthesis and secretion of androgens
androgens in turn stimulate the process of spermatogenesis
Who does FSH work as what does it do
FSH acts as the sertoli cells and helps in the secretion of some Factors that help innthe process of spermatogenesis
Parts of the sperm
Microscopic structure composed of head neck middle piece and a tail
First outer layer of sperm
A plasma membrane envelops the whole body of the sperm
Constituents of sperm head
The sperm heads contains an elongated haploid nucleus the anterior portion of which is covered by a cap like structure called acrosome
What is the acrosome
What is it made of and it’s function
The cap like structure is called the acrosome which is filed with enzymes that help in fertilisation of ovum
Middle piece constituents and functions
The middle piece contains numerous mitochondria which produce energy for the movement of the tail that facilitate sperm motility essential for fertilisation
How many sperms released during coitus
The human male ejaculates about 200-300 million sperms during coitus out of which 60 percent have normal shape and size and out of those 40 percent show vigorous motility
Which secretion help in sperm motility
Secretion of epididymis vas deferens seminal vesicle and prostate are essential for maturation and motility of sperm
Semen constituents
The seminal plasma along with the sperms constitute the semen
Who maintains the function of the male accessory ducts and glands
Androgens
What is oogenesis
Oogenesis is the formation of mature female gamete
When does oogenesis start
Why is it initiated
How many oogenesis formed in each fetal Ovary
What is oogonia
Oogenesis is initiated during the embryonic development stage when a couple of million gamete mother cells (oogonia) are formed within each fetal Ovary no more oogenia are formed or added after birth
Primary oocyte stuck stage
When female egg cells enter into prophase 1 of the meiotic division and get temporarily arrested at that stage called primary oocyte
What is primary follicle
Each primary oocyte gets surrounded by a layer of granuloma cells and is called the primary follicle
Degeneration period of follicles
A large number of follicles degenerate from the period of birth to puberty therefore at puberty only 60000 to 80000 follicles are left at each Ovary
What happens to follicles during puberty
Therimary follicles get surrounded by more layers of granulosa cells and a new thecal and are called Secondary follicles
Tertiary follicle and speciality
The Secondary follicle soon transforms into tertiary follicle which is characterized by a fluid filled cavity called antrum
Parts of the theca layer
Inner theca layer
Outer theca layer
Cytoplasm division ratio between polar body and Secondary oocyte
Secondary oocyte retains bulk of the nutrient rich cytoplasm of the primary oocyte
Final follicle stage
The tertiary follicle further changes into the mature follicle or graafian follicle
When is Zona pallucida formed what is it
The Secondary oocyte forms a new membrane called Zona pellucida surrounding it
What is ovulation
The graafian follicle ruptures to release the Secondary oocyte from the Ovary by the process called ovulation
