Reproductive Systems Overview and Anatomy

Reproductive Systems Overview

• Reproductive systems are designed to perpetuate species.
• Male gamete is the sperm cell.
• Female gamete is the ova cell.
• Fertilization occurs when sperm and ovum join, forming a zygote.
• Haploid and diploid are terms describing the number of chromosomes in a cell.
• The reproductive system includes gonads (Testes/Ovaries), reproductive tract, accessory glands, and perineal structures (external genitalia).

Male Reproductive System Anatomy

• Ducts: Ejaculatory duct, membranous urethra, spongy urethra, ductus deferens, epididymis.
• Gonad: Testis.
• External Genitalia: Penis, scrotum.
• Accessory Glands: Seminal gland, prostate gland, bulbo-urethral gland.
• Testis size: 5cm long; 3cm wide; 2.5cm thick; 10-15g.
• Testes develop inside abdominal cavity, near kidneys during development, then descend toward scrotum (spermatic cords maintain connections to testes).

The Testes

• Testes are housed in scrotum, located outside of the body at a slightly cooler temperature than the body core.
• Necessary for sperm production.
• Scrotum is divided into two chambers (scrotal cavities) separated by perineal raphe; extends from anus, across scrotum, along anterior surface of penis.
• Tunica vaginalis is a membrane covering each testis, lining the scrotal cavity.
• Cremaster muscle within cremasteric fascia; contraction tenses the sac.
• Dartos muscle; contraction causes wrinkling of scrotal surface.

The Spermatic Cords

• Ductus deferens, blood vessels, lymphatics, and nerves remain bundled together, linking the testes to the body and other parts of the reproductive system.

The Male Reproductive Tract

• Epididymis: Receives sperm via efferent ducts, coil of tubes carrying the sperm, then continues to the ductus deferens.
• Ductus deferens: Moves sperm from epididymis to urethra; increases in size to form ampulla.
• Urethra: Monitors and adjusts fluids produced by seminiferous tubules; recycles damaged sperm; aids sperm maturation and transports sperm out of body. It has three sections: Prostatic, Membranous, and Spongy.

Accessory Glands

• Seminal glands: (~60% of semen volume); contains fructose, prostaglandins, clotting factors.
• Prostate gland: (~20-30% of semen volume); produces weakly acidic fluid; seminalplasmin to prevent UTIs.
• Bulbo-urethral glands: (~5% of semen volume); produces thick, sticky, alkaline mucus to neutralize acids, lubricate penis.

Ejaculate

• Semen (sperm + seminal fluid + prostate fluid), each ejaculate = ~1 teaspoon.
• 200-500 million sperm per ejaculation.

Penis

• Multifunctional organ; sexual pleasure, urination and reproduction.
• Composed of spongy tissues (Corpora cavernosa (top) and Corpus spongiosum (bottom)), no bones.
• Urethra passes through penis.
• Tumescence (filling process with blood) signals sexual arousal.
• Root, body, glans and external urethral orifice are the major anatomical parts.

Genital Asymmetry in Men

• Reported in a study which interviewed men who were non-delinquent, showing asymmetry in flaccid penises and testicles, less asymmetry noted in erect penis.
• Asymmetry typically occurred on the left side.

Female Reproductive System Anatomy

• Gonad: Ovary.
• Uterine tube (Fallopian tube): Infundibulum, ampulla, isthmus, uterine part, fimbriae.
• Uterus: Major components include the body, uterine cavity, fundus, and cervix.
• Vagina: Extends from cervix of uterus to external genitalia; around 7.5-9cm in length; close proximity to urethra and rectum.
• External Genitalia: Mons pubis, labia majora, labia minora, clitoris.

Accessory Glands for Female Reproductive System

• Paraurethral glands (Skene's glands), located near urethra.
• Greater vestibular glands (Bartholin's glands), located near vaginal opening (vestibule).

Ovaries

• Where eggs, also called oocytes, are produced.
• Structures like mesovarium and mesosalpinx (with broad ligaments) hold ovaries in place.
• Internal structures (cortex and medulla) house follicles.

Mammary Glands

• Structure containing lobules, lactiferous ducts, and lactiferous sinuses, important for milk production during pregnancy and lactation.

Ovarian Cycle and Oogenesis

• The cycle develops from puberty onward.
• Stages include primary follicle development to secondary follicle and tertiary follicles; maturation is crucial for ovulation.
• Ovulation: release of an egg under influence of luteinizing hormone (LH).
• Corpus luteum develops after ovulation, creating progesterone to support pregnancy.
• If pregnancy does not occur, the corpus luteum decomposes into the corpus albicans.

The Uterine Cycle (Menstrual cycle)

• Consists of three phases: proliferative phase, secretory phase, and menses.
• Menarche: the first uterine cycle at puberty.
• Proliferative phase: endometrial lining thickens to prepare for a fertilized egg; occurs parallel to primary/secondary follicle enlargement in ovaries.
• Secretory phase: endometrial glands and blood vessels grow; egg is prepared for possible implantation if fertilized.
• Menses: Due to a decrease in estrogen and progesterone levels (end of cycle); this causes blood vessels to contract, resulting in endometrial cell loss; this is menstruation.
• Menopause: last uterine cycle.

The Cervix

• Lower end of the uterus; opening to vagina.
• Opening (Os) is typically narrow but can expand.

Histology

• The details of specific tissues' (e.g., uterine wall, ovaries, vagina) structure, particularly at the cellular level.

This quiz covers the key concepts of the reproductive systems, focusing on both male and female anatomy. Participants will learn about gametes, fertilization, and the specific structures within the male reproductive system. Test your understanding of how these systems operate and their significance in species perpetuation.