Male Reproductive System

The Reproductive Systems Reproductive organs are grouped by function Gonads - testes and ovaries produce gametes and secrete hormones produce gametes and fluid; then discharge into duct system indicates exocrine function production of hormones indicates endocrine function Ducts – receive, store, transport gametes Accessory sex glands – support gametes Supporting structures - various reproductive functions

The reproductive system becomes active after puberty The reproductive system becomes active after puberty. During puberty the reproductive organs mature to create a fertile individual capable of reproducing. The primary sex organs produce the sex cells (egg/sperm) and sex hormones. The accessory sex organs are all the components involved in maintaining the sex cell and assisting in the process of fertilization.

Organs: Testes – produce sperm and sex hormones. Hormones influence sperm production and secondary sex traits. Epididymides – sperm maturation, storage Vas Deferentia – rapid transport of sperm Ejaculatory Ducts – conduct sperm to penis

Accessory Glands: 2 Seminal Vesicles – secrete fructose (sperm use this sugar for energy) and prostaglandins (induce muscles to contract) 1 Prostate Gland – secretes most of the liquid part of semen (sperm + glandular secretions). May help buffer the low pH (3.5-4.0) of vaginal fluid. 2 Bulbourethral (Cowper’s) Glands – a mucus-rich lubricant

Male reproductive system is simpler than the female reproductive system. A. Scrotum: a sac located outside of the abdominal cavity, made up of a thin layer of smooth and skeletal muscle and skin. It is divided into left and right by a septum to form different compartments for the testicles. The scrotum keeps the testicles outside the body so they can be 3 degrees cooler than normal core temperature. The muscles of the scrotum contract to bring the testicles closer to the body in cooler conditions. In warm conditions they relax to allow the skin to stretch and maximize cooling.

B. Testes: Oval shape organs made up of thousands of seminiferous tubules where the sperm is produced. It responds to follicle stimulating hormone that signals sperm production. When the sperm is in its last stages of maturation it moves to the epididymus.

Function: produce hormones (testosterone) responsible for secondary sex characteristics such as deeper voice, facial hair, larger muscles, and body hair produce sperm

1. Gross anatomy: about 1 x 4 inches, complete surrounded by a fibrous capsule and partially enclosed by a serous membrane that develop when the testes traveled outside the body into the scrotum. The fibrous capsule divides the testicles into wedge-like compartments called lobules that are filled with seminiferous tubules. They are innervated by an abundant about of visceral sensory nerves that make them very sensitive to pain. The testis is covered by a dense collagenous coat called the tunica albuginea. there is a prominent vascular layer immediately beneath the tunica albuginea.

The abundant seminiferous tubules all lead into the mediastinum of the testis, separated from the rest of the testis by the tunica albuginea as well. The mediastinum includes the rete testis, which lead to the efferent ducts and then the epididymis at the posterior aspect of the testis.

The ductus deferens is continuous with the tail of the epididymis, it passes through the superficial inguinal ring in the spermatic cord, through the inguinal canal, exits the deep inguinal ring, and joins the duct of the seminal vesicle to form the ejactulatory duct.

MALE REPRODUCTIVE SYSTEM TUNICA ALBUGINEA  TESTIS Mediastinum containing RETE TESTIS EPIDIDYMIS testis-06 LOBULES

2. Seminiferous tubules and spermatogenesis: The seminiferous tubules consist of a thick stratified epithelium surrounding a lumen. The epithelium has spermatogenic cells that mature into sperm. At puberty the seminiferous tubules begin to produce about 400 million sperm. the spermatogenic cells are protect by a blood-testis barrier that keep the cells from activating the immune system.

MALE REPRODUCTIVE SYSTEM SEMINIFEROUS EPITHELIUM - complex stratified epithelium containing two basic cell populations: (1) SPERMATOGENIC CELLS stem cells which regularly replicate and differentiate into mature sperm as they migrate toward the lumen 4 (2) SERTOLI CELLS nonreplicating physical support cells INTERSTITIAL CONNECTIVE TISSUE (1) LEYDIG CELLS produce and release testosterone

MALE REPRODUCTIVE SYSTEM  SPERMATOGENESIS SPERMATOGONIA 1º SPERMATOCYTE 2º SPERMATOCYTE SPERMATIDS SPERMATIDS 2º SPERMATOCYTE tight junctions of lateral processes may temporarily open to permit the passage of spermatogenic cells toward the lumen 1º SPERMATOCYTE SERTOLI CELLS: - columnar with adjoining lateral processes - extend from basal lamina to lumen - Sertoli-Sertoli junctions divide seminiferous tubules into basal and adluminal compartments SERTOLI CELLS SPERMATOGONIA

MALE REPRODUCTIVE SYSTEM SEMINIFEROUS TUBULES  SPERMATOGENESIS THREE PHASES: (1) Spermatogonial Phase (Mitosis) - spermatogonia proliferate by mitotic divisions to provide stem cells and cells which will proceed through spermatogenesis (1º spermatocytes) (2) Spermatocyte Phase (Meiosis) - diploid cells (2n) created in spermatogonial phase give rise to haploid cells (1n) - Meiosis I (reduction division) & Meiosis II (equatorial division) - 1º spermatocytes enter Meiosis I to form 2º spermatocytes which then enter Meiosis II and result in spermatids 5 exchange of genetic material in MI via crossing over (3) Spermatid Phase (Spermiogenesis) - spermatid differentiation into spermatazoa

Spermatogenesis: these are the stages involved in sperm formation. Stage 1: formation of spermatocytes: spermatogonia divide by mitosis to produce two daughter cells, one remains in the germ line (to continue regeneration of more spermatogonia) and the other one goes on to become sperm.

primary spermatocytes, larger nuclei mid wsay up in the epithelium. The nuclei are round with distinct bundles of dense chromosomes. These cells are in extended prophase of the first meiotic division.

Stage 2: Meiosis: this is a reduction division that takes a cell through two rounds of division. At the end four genetically distinctive cells (spermatids) are created which will each mature into a sperm.

Stage 3: Spermiogenesis: spermatids mature into sperm, the cell develops a long flagella, a mid piece with high mitochondria count, and a “head” filled with DNA= the nucleus. At the tip of the head lies a sac filled with digestive enzymes called the acromosome

Sperm have three major regions Head – contains DNA and has a helmet like acrosome containing hydrolytic enzymes that allow the sperm to penetrate and enter the egg Midpiece – contains mitochondria spiraled around the tail filaments Tail – a typical flagellum produced by a centriole

Other cells in the testicles perform jobs like assisting the cells to mature and exit the scrotum (referred to as nurse cells), produce male androgen (like testosterone), and muscular cells that cause tiny contractions to push the sperm out of the testes. When sperm leaves the seminiferous tubules it travels down the efferent tubules towards the epididymis.

Sertoli cells are large, relatively pale and irregularly shaped. We can see a prominent nucleolus within the Sertoli cell nucleus. These cells primarily support and nourish the germ cells in the testis with long, apical cytoplasmic folds. They contain testosterone and FSH receptors.

Leydig cells Within the loose connective tissue of the testis, among seminiferous tubules, These cells secrete the male steroid hormone, testosterone. There may be small capillaries found among the clusters of Leydig cells.

Fully formed spermatozoa leave the seminiferous tubules by straight tubules and enter interconnected channels called rete testis within the mediastinum (bottom left). These flattened channels are lined with low cuboidal epithelium. As mentioned before, the mediastinum contains the dense connective tissue of the tunica albuginea.

MALE REPRODUCTIVE SYSTEM  EFFERENT DUCTULES CONNECT RETE TESTIS WITH EPIDIDYMIS IRREGULAR LUMINAL APPEARANCE DUE TO TALL CILIATED CELLS AND SHORT NON-CILIATED CELLS CILIATED CELLS BEAT TOWARD EPIDIDYMIS; THIN LAYER OF SMOOTH MUSCLE ALSO AIDS MOVEMENT INTO EPIDIDYMIS 6

MALE REPRODUCTIVE SYSTEM  EPIDIDYMIS RECEIVES EFFERENT DUCTULES DIVIDED INTO HEAD, BODY, AND TAIL PSEUDOSTRATIFIED EPITHELIUM CONSISTING OF PRINCIPAL AND BASAL CELLS SMOOTH MUSCLE IN HEAD AND TAIL CONTRACT SPONTANEOUSLY; SMOOTH MUSCLE IN TAIL REQUIRES SYMPATHETIC INNERVATION FOR CONTRACTION 7

EPIDIDYMIS STEREOCILIA MATURE SPERM epididymus-04

EFFERENT DUCTULES EPIDIDYMIS epididymus-06

EFFERENT DUCTULES EPIDIDYMIS epididymus-07

epididymus-08 EPIDIDYMIS

MALE REPRODUCTIVE SYSTEM  VAS DEFERENS CONNECTS EPIDIDYMIS WITH SEMINAL VESICLES PSEUDOSTRATIFIED COLUMNAR EPITHELIUM SMOOTH MUSCLE ARRANGED IN 3 LAYERS SMOOTH MUSCLE CONTRACTION VIA SYMPATHETIC STIMULATION DURING EJACULATION 8

VAS DEFERENS H&E vas-02

Seminal Vesicles Pair of exocrine glands responsible for secreting 85% of total volume of seminal fluid. Each seminal vesicle is a complex glandular diverticulum of the associated ductus deferens

The Lumen The lumen is highly irregular, recessed and thrown into tortuous folds Lumen gives honey combed appearance at low magnification. The wall composed of three layers Mucosa. Muscularis. Adventia.

The Muscularis Composed of inner circular and outer longitudinal layer Supplied by sympathetic nervous system During ejaculation, muscle contraction forces secretions from the seminal vesicles into the urethra

MALE REPRODUCTIVE SYSTEM  SEMINAL VESICLES EPITHELIUM PSEUDOSTRATIFIED 14

Prostate gland exocrine gland located inferior to the bladder. It secretes various components of semen including citric acid and acid phosphatase as the ejaculatory duct passes through it. The opening of the ejaculatory duct is found at the seminal colliculus, where the contents are emptied into the prostatic portion of the urethra.

A partial capsule surround posterior and lateral aspect of prostate Anterior and apical surfaces are bounded by a part of the gland itself, the anterior fibromuscular stroma The fibromuscular stroma is composed of collagenous stroma and muscle fibers

The Supporting Stroma A mixture of collagen fibrous tissue and smooth muscle fibers.

MALE REPRODUCTIVE SYSTEM  PROSTATE 30-50 TUBULOALVEOLAR GLANDS WHICH EMPTY INTO URETHRA 10

MALE REPRODUCTIVE SYSTEM  PROSTATE SIMPLE OR PSEUDOSTRATIFIED COLUMNAR EPITHELIUM 12

MALE REPRODUCTIVE SYSTEM  PROSTATE PROSTATIC CONCRETIONS - precipitation of secretory product 11

Bulbourethral Glands of Cowper A pair of pea sized bodies lying posterolateral to the membranous urethra Covered by thin connective tissue capsule Each gland is composed of tubulo-acinar gland whose ducts drain into the proximal part of penile urethra

MALE REPRODUCTIVE SYSTEM  URETHRA PROSTATIC, MEMBRANOUS, SPONGY (PENILE)

PENIS CC CC URETHRA penis-01 CS

Penis: The glans of the penis at the tip, connected to the bulb via the corpus spongiosum. The corpus cavernosum is on both sides, connected to the ischial tuberosity. The superficial dorsal, and lateral superficial veins underneath the skin but outside the tunica albuginea. The deep dorsal vein, dorsal artery, and dorsal nerve within the tunica albuginea. The deep artery within the corpus cavernosum. The urethra within the corpus spongiosum.