HUMAN REPRODUCTION

Fertilization – The union of a haploid/monoploid (n) sperm nucleus with a haploid/monoploid (n) egg nucleus. Result = a diploid (2n) zygote

REPRODUCTION AND DEVELOPMENT IN HUMANS Male Reproductive System Three main functions 1. Production of sperm 2. Deposit sperm within the female reproductive tract 3. Produce hormones

Testes are located in the scrotum, where the temperature is 2-4 degrees Celsius below body temp. (This provides an optimal temp. for the production and storage of sperm). Sperm are stored in the epididymis.

Male Reproductive System Seminal Vesicle Urinary Bladder Prostate Urethra Penis Rectum Epididymis Cowper’s Gland Testis Vas deferens Scrotum

1. Semen – sperm (male gamete) PLUS the fluids secreted from the Cowpers Gland, Seminal Gland and Prostate Gland – these fluids carry, nourish, and protect the sperm 2. Testes – male gonads (reproductive organs) which produce the hormone testosterone (responsible for male secondary sex characteristics) and sperm (male gamete) – located outside abdominal cavity within the 3. Scrotum a saclike pouch ~2-4°C below normal body temperature- sperm can only form at this lower temp.

Male Reproductive System 1. Seminiferous tubules: coiled tubes in the testes where sperm are produced 2. Epididymis: a series of coiled tubes where sperm are stored and mature 3. Vas deferens: tube which carries sperm from each testis, past the lubricating glands to the urethra

4.Lubricating Glands – produce fluids that allow for organisms to reproduce on land (a.) Seminal vesicles: glands that secrete fluid containing fructose to nourish sperm and a fluid that is alkaline (basic) to protect them from the acidity of the female reproductive tract (b.) Prostrate gland: a gland that produces a fluid that is milky white in color and contains enzymes and proteins to protect and support the sperm during ejaculation (c.) Cowper’s glands: also known as bulbourethral glands, secrete an alkaline (basic) fluid to lubricate the urethra and neutralize urine that remains

Male Reproductive System 5. Urethra: tube in the penis that transports sperm out of the male’s body; also transports urine from the urinary bladder. 6. Penis: the male reproductive organ (copulatory organ) that releases semen and allows for internal fertilization 7. Ejaculation: the release of semen

Sperm move through a series of ducts to the urethra in the penis. Glands such as the cowper’s gland, seminal vesicle, and prostate secrete various fluids into these ducts

Female Reproductive System Ovaries produce eggs (ova) in tiny cavities called follicles. All of the potential eggs that a female will ever release are present in an immature form at birth.

Female side view diagram Oviduct(Fallopian Tube) Ovary Urinary Bladder Uterus Urethra Rectum Cervix Vagina

Ovaries - female gonads (reproductive organs) which produce the sex hormones estrogen and progesterone (responsible for female secondary sex characteristics and regulating the menstrual cycle) – produce eggs/ova (female gamete) - functional from puberty to menopause Oviducts (Fallopian Tubes) - tubes that carry the egg away from the ovary – fertilization occurs here

Uterus (womb) - thick, muscular, pear-shaped organ in the female mammal in which the embryo develops Vagina - the structure leading from the uterus to the outside of the body in mammalian females AKA… THE BIRTH CANAL Cervix - the lower, narrow end of the uterus

Ovulation – once a month, a follicle will rupture and release one egg

Female Frontal View Fallopian Tube (Oviduct) Thickened Uterine Lining Egg (n) Ovary Cervix Follicle Sperm Cell (n) Vagina Back to 15 Back to 16

After the egg is released from a follicle, it is transported to the uterus through an oviduct or fallopian tube. Female - side view diagram

Temporary cessation during pregnancy Permanent cessation at menopause Menstrual Cycle Begins at puberty (females age 11-12) Temporary cessation during pregnancy Permanent cessation at menopause (approximately ages 45-55) The cycle lasts about 28 days Preparation of the uterus for a fertilized egg

Cycle consists of 4 stages Follicle stage - Follicle Stimulating Hormone (FSH) is secreted from anterior pituitary gland and it stimulates an egg to mature in the follicle - the ovary also produces the hormone estrogen which initiates the vascularization (increased blood supply) of the uterine lining Ovulation stage - egg is released from the follicle (approximately day 14) and Luteinizing Hormone (LH) is secreted from the anterior pituitary gland Corpus Luteum stage – the follicle becomes a corpus luteum which secretes the hormone progesterone which enhances the vascularization of the uterine lining

Menstruation Stage - the periodic shedding of the thickened uterine lining - it occurs when fertilization does not take place – a new cycle begins with the first day of menstruation