Session -5 Organ Development

Life cycle of sexual organisms

What is the Function of the Prostate? The prostate is a walnut-sized gland located behind the base of the penis, in front of the rectum and below the bladder It surrounds the urethra, the tube- like channel that carries urine and semen through the penis The primary function of the prostate is to produce seminal fluid, the liquid in semen that protects, supports, and helps transport sperm

Sperm Unlike the egg, sperm are streamlined cells that contain only the protein components needed for movement and ultimate entry into the egg. Each sperm cell contains a minimal cytoplasmic constituent, a nucleus bearing a haploid complement of the male DNA. 1)In mature sperm nuclei, the DNA is compact. 2) The acrosome is loaded with enzymes that digest complex carbohydrates and proteins on the outer surface of the egg.

What is the Cervix [ser-vix]? The cervix is one of the female organs Other female organs include the: The vulva is the female organ just outside the vagina. The vagina is the opening between the vulva and the bottom of the cervix. The cervix is the narrow outer end (or neck) of the uterus (or womb). During sex, sperm from the male get into the fallopian tubes through the cervix. This is where the sperm meet the egg from the female. Cervix is inside your body, It allows sperm to get to the uterus. It also holds the baby in the womb until the baby is ready to be born.

Fertilization Fertilization refers to the union of the sperm and the egg 1)First, chemo attractants secreted by the egg induce the sperm to swim toward it. 2) The enzymic contents of the sperm acrosomal vesicle are released by exocytosis either just prior to or after the sperm binds to the extracellular surface of the egg, which is called the zona pellucida or the vitelline envelope in mammals. 3) The acrosomal enzymes begin to degrade the surface of the egg so that finally there can be fusion of the sperm and egg membranes. 4) When sperm enters the egg, its haploid nucleus combines with the haploid nucleus of the egg to form a diploid nucleus. The early fertilized egg is now referred to as the zygote.

The transformation of inner cell mass of the blastocyst into an embryo is called gastrulation.

The final steps of embryonic development include organogenesis leading to a fully formed embryo during this period ICM becomes organized into three distinct layers called germ layers. The three layers are the ectoderm, the mesoderm, and the endoderm.

The Skin

Keratinocyte Stem cell (KSC) Unipotent keratinocyte stem cell reside within the basal layer of the epidermis and are responsible for the renewal of a tiny portion of the epidermis. Multipotent keratinocyte stem cells are located in the upper region of the hair follicle below the sebaceous glands, and are characterized by their capacity for self- maintenance and self- renewal.