Spermatogenesis and Anatomy

Anatomy

• Seminiferous tubules are present
• The epididymis exists
• The epididymis leads into the vas deferens
• The vas deferens enlarge into the ampulla vas deferens
• The internal urethra contain secretions of the accessory glands mixed with sperm
• The urethra exists

Spermatogenesis

• This refers to the sequence of events that create sperm in seminiferous tubules of the testes
• Each cell has two sets of chromosomes(one maternal, one paternal) and is a diploid, ie 2n chromosomal number
• Human beings have 23 sets of homologous chromosomes
• Gametes only have 23 chromosomes and are thus haploid, ie n chromosomal number
• Gamete formation occurs by meiosis, where number of chromosomes are halved from 2n to n
• Spermatogenesis starts at puberty and goes on throughout most of span of life, decreasing substantially in senility
• Spermatozoon (sperm) gets produced in seminiferous tubules
• Spermatogonia refers to stem cell
• Primary spermatocyte
• Secondary spermatocyte
• Spermatid
• Spermatozoon

Sex Chromosomes

• One of the 23 pairs of chromosomes in each spermatogonium is the genetic information to determine the sex of eventual offspring
• This pair is made up of one Y chromosome, which is the male chromosome
• During meiotic division, the male Y chromosome goes to one spermatid to be a male sperm
• The female X chromosome goes to another spermatid to be a female sperm
• The sex of an offspring is determined by which type of sperm fertilizes the ovum

Spermiogenesis

• Toward the end of spermatogenesis, spermatids are haploid but nonmotile
• Spermiogenesis refers to spermatids losing excess cytoplasm and forming a tail, becoming sperm
• The sperm are divided up into three main regions
• The head contains DNA and has a helmetlike acrosome containing hydrolytic enzymes to let the sperm penetrate and enter the egg
• The mid piece contains mitochondria spiraled around the tail filaments
• The tail is a typical flagellum produced by a centriole

Hormonal Factors

• Hormonal factors that Stimulate Spermatogenesis
• Testosterone causes the production of sperm
• Leutinising Hormone (LH) causes the production of sperm
• Follicle Stimulating Hormone (FSH) causes the production of sperm
• Estrogens(formed from testosterone by sertoli cells) causes the production of sperm
• Growth Hormone causes the production of sperm

Sperm Maturation in the Epididymis

• Two testes form up to 120 million sperm per day in the human adult with a small amount stored in epididymis as the most is stored in vas deferens to maintain reproduction .
• Post duration of 18-24 hrs in the epididymis the sperm produce motility even if some inhibitory proteins do not let ejaculation of the final motility.
• Normal motile , fertile has the ability of flagellated which is observed at velocities of 1-4mm/minute.
• Even if sperm are living for many weeks in the suppressed testes, the life span of ejaculated sperm is approximately 1-2 days in the female genital of tract.

Seminal Vesicles

• The seminal vesicles exist on the posterior bladder, and secretes 60% of semen volume
• The semen comprises is a viscous fluid that contains fructose, citric acid, fibrinogen, and prostaglandins
• Join up with the ductus deferens to produce the ejaculatory duct
• Sperm and seminal fluid combine to make the ejaculatory duct and start the prostatic urethra during ejaculation

Prostate Gland

• Doughnut shaped gland near urethra
• Fluids are alkaline, slightly milky which accounts for one third of semen volume
• Slightly alkaline prostatic fluid helps to neutralize the acidity of the seminal vessels.
• This fluid enhances sperm production and motility.

Semen

• Sticky, milky mix of sperm and glands
• Gives transport medium and nutrients that protect and activate sperm facilitating their movement
• Prostaglandins reduces the viscosity of mucus in cervix
• Stimulates reverse peristalsis in uterus
• helps speed up the movement of sperm along a females reproductive system
• Consists of relaxin, to enhance the sperm motility
• Has an alkalinity to reduce the acid found in males and females
• Includes antibiotics known as seminal plasmin
• Consists of clotting components for coagulation from ejaculation
• Includes a range of 2-5ml and comprises of 50-130 sperm ml

Male Sexual Response - Erection

• Stiffening and Enlargement of the penis from engorgement of tissue wth blood
• A PNS reflex promotes the release or production of Nitric Oxide during sexual arousal
• Nitric Oxide fills tissue in the erectile structures
• The expansion caused by corpora cavernosa
• compresses their draining veins
• reduces amount of blood that can flow out
• Keeps the urethra open through the process of ejaculation known as corpus spongiosum

Male Sexual Response

• Erection: sexually created through touches of the penis, sounds, and smell
• The inhibition process is emotionally stimulated through high mental activity
• Inability to attain an erection refers to impotence

Ejaculation

• Emission occurs

Ejaculation

• Semen propulsion from duct
• sympathetic nerves cause:
• Reproductive components to empty contents
• Bladder muscles can contract to prevent urination
• bulbospongisous causes rapid contractions
• Sperm propulsion of the Urerthra

Capacitation in Spermatozoa

• Fluids remove the inhibitory factor
• Cholesterol is added during semen process, toughens and prevents from enzymes being released
• Sperm is dropped out with cholesterol and lose energy after a few hours to make acrosome weaker
• Membrane becomes permeable, flagellum activity is increase to a strong force
• Changes within calcium that will release enzymes.