Introduction to the Male Half of Reproductive Biology

Introduction to the Male Half of Reproductive Biology
By:Genevieve Griffiths
University Of Delaware

Why Study Sperm Biology?
* One in six couples are infertile.
* In 40 per cent of cases the problem lies exclusively with the male, known as Male Factor Infertility.
* One in 25 males have a low sperm count, and one in 35 are sterile.
* With appropriate treatment, many couples struggling with male factor infertility are able to conceive.

Sexual Reproduction
* Occurs when two gametes (sperm + egg, 1N or ½ genome) combine genetic material (DNA) to form a zygote (embryo, 2N or 1 genome)
* Recombination permits genetic flexibility within a population (can lead to evolution)
* Offspring have characteristics from both parents as well as those unique from parents
* Sperm production is known as spermatogenesis
* Five mitotic divisions produce 16 primary spermatocytes from a single cell
* Two meiotic divisions produce 64 spermatids

Spermatogenesis
* Mitosis (2N (46 chromosomes) to 2N) must occur to create many cells from a single cell
* Meiosis (2N to 1N (23 chromosomes)) must occur to divide DNA in half

After meiosis, sperm dramatically change shape
Testes and Epididymis
* Spermatogeneis occurs in the seminiferous tubules of the testes
* Sperm maturation occurs in the epididymis

Immature Sperm
Mature Sperm
Mammalian Fertilization
cumulus
cells
zona
pellucida
Egg
Mammalian Fertilization
cumulus
cells
Oocyte

Introduction to the Male Half of Reproductive Biology.ppt