Male Reproduction PDF

MALE REPRODUCTION LOUISE ARNOLD LEARNING OUTCOMES 01 02 03 04 05 06 BRIEFLY DESCRIBE THE EMBRYOLOGICAL DEVELOPMENT OF THE MALE REPRODUCTIVE SYSTEM OUTLINE THE KEY FEATURES AND FUNCTION OF THE TESTES AND SPERMATIC CORD DISCUSS THE FASCIAL LAYERS SURROUNDING THE TESTICLE OUTLINE THE ACCESSORY SEX GLAN...

MALE REPRODUCTION LOUISE ARNOLD LEARNING OUTCOMES 01 02 03 04 05 06 BRIEFLY DESCRIBE THE EMBRYOLOGICAL DEVELOPMENT OF THE MALE REPRODUCTIVE SYSTEM OUTLINE THE KEY FEATURES AND FUNCTION OF THE TESTES AND SPERMATIC CORD DISCUSS THE FASCIAL LAYERS SURROUNDING THE TESTICLE OUTLINE THE ACCESSORY SEX GLANDS, THEIR FUNCTION AND SPECIES DIFFERENCES OUTLINE THE GROSS ANATOMY OF THE PENIS AND SPECIES DIFFERENCES COMPARE THE KEY FEATURES OF THE MUSCULO CAVERNOSUS PENIS AND FIBROELASTIC PENIS AND HOW ERECTION IS ACHIEVED CONFIDENTIAL AND NOT FOR DISTRIBUTION, COPYRIGHT OF UNIVERSITY OF BRISTOL THE TESTICLE AND SCROTUM TESTES AND SPERMATIC CORD E.A.O m. aponeurosis Inguinal ligament Superficial inguinal ring External pudendal vessels Genitofemoral nerve External cremaster m. Spermatic cord Testicle – site of spermatogenesis and testosterone production Epididymis – site of storage and maturation of sperm Vaginal tunic – Invagination of the peritoneum that accompanies the spermatic cord into the scrotum. Forms the parietal and visceral vaginal tunic Testicular artery - supplies testes and epididymis Spermatic cord Pampiniform venous plexus (testicular vein) - testicular vein surround tortuous testicular artery acting as a counter current heat exchange Testicular nerve– supply testes and epididymis Ductus deferens – carries sperm in spermatic cord from epididymis to join urethra within pelvic cavity Mesoductus deferens & Mesorchium – a supportive peritoneal fold External cremaster muscle - extension of IAO fibres (OUTSIDE vaginal tunic) Genitofemoral nerve – supplies cremaster m., spermatic cord, skin of scrotum, prepuce ANATOMICAL FEATURES TESTICULAR DESCENT TESTICLES DEVELOP RETROPERITONEALLY NEAR THE KIDNEYS DESCENT THROUGH THE INGUINAL CANAL INTO THE SCROTUM IS GUIDED BY THE GUBERNACULUM AND UNDER HORMONAL INFLUENCE RESULTS IN SEVERAL LAYERS SURROUNDING THE TESTICLE DEVELOPMENT OF MALE GONADAL LIGAMENTS Cranial gonadal ligament degenerates Caudal gonadal ligament (gubernaculum): proper ligament of the testis ligament of the tail of the epididymis scrotal ligament SCROTAL LAYERS This is clinically important as the type of castration performed dictates which layers are incised. Closed castration - Incise skin/Dartos muscle - Blunt dissection of superficial spermatic fascia - Breakdown scrotal ligament Open castration - Incise skin/Dartos muscle - Blunt dissect external spermatic fascia - Incise internal spermatic fascia - Incise parietal vaginal tunic - Breakdown ligament of the tail of the epididymis https://inpractice.bmj.com/content/inpract/23/5/250.full.pdf Castration techniques in the horse https://inpractice.bmj.com/content/inpract/38/2/69.3.full.pdf Urogenital surgery in farm animals ( includes castration and vasectomy) https://youtu.be/QK7Zpk-vqoM?t=75 vasectomy in the ram - will start at 1.14 minutes CASTRATION IN THE DOG: – OPEN VS CLOSED COMPARATIVE TESTES Differing location and orientation https://tipsytoadgrove.com/?p=1496 https://www.shutterstock.com/ https://pxhere.com/ THE PENIS CANINE PENIS Musculocavernous type Large cavernous spaces fill up with blood during erection Glans divided into pars longa glandis and bulbus glandis involved in copulatory lock Penis: Corpus Spongiosum Cavernous erectile tissue (purple) surrounds urethra (orange) Penis: Corpus cavernosum Pair of cavernous bodies (corpora cavernosa - red) dorsal to penile urethra (orange)/corpus spongiosum (purple) tissue Forms crura attaching penis to ischial arch Ossifies distally forming Os Penis CANINE PENIS Corpus spongiosum Erectile tissue surrounding penile urethra. Expands distally to form Glans penis (bulbus glandis & pars longa glandis) Corpora cavernosa ▪ Two columns erectile tissue ▪ Distally becoming os penis in dog ERECTION IN THE MUSCULOCAVERNOUS PENIS (DOG, HORSE, MAN) Function of venous engorgement Flaccid penis - tonic contraction of smooth muscle in walls of cavernous spaces and retractor penis muscle controlled by sympathetic nerves Erection - inhibition of sympathetic tone (upregulation parasympathetic tone) Ischiocavernosus, ischiourethralis, and bulbospongiosus compress venous return Engorgement of blood, causing swelling (increase in length and width) Image from Nottingham Vet School Paraphimosis Inability to retract penis within prepuce COPULATORY LOCK IN THE DOG https://commons.wikimedia.org/w/index.php?curid=25476664 Copulatory lock: complete swelling of bulbus glandis – constriction of dorsal vein, constrictor vestibuli muscle also causes constriction of superficial vein of glans COMPARATIVE PENIS AP text page 89 TWO BASIC TYPES MUSCULOCAVERNOUS LARGE CAVERNOUS HORSE, DOG, MAN SPACES WHICH FILL UP WITH BLOOD DURING ERECTION E.G. FIBROELASTIC MUCH FIBROELASTIC TISSUE, SMALL CAVERNOUS RUMINANTS, PIG SPACES, SIGMOID FLEXURE E.G. CONFIDENTIAL AND NOT FOR DISTRIBUTION COPYRIGHT OF UNIVERSITY OF BRISTOL. Dorsal veins of the penis Corpus cavernosum (note the difference in fibroelastic tissue present) Urethra Corpus spongiosum Fibroelastic Retractor penis muscle Musculocavernosus ERECTION - FIBROELASTIC e.g. ruminant, pig Fibrous tissue means penis inherently stiff Sigmoid flexure retains penis within prepuce, retractor penis contracted Engorgement restricted to sigmoid flexure, retractor penis muscle relaxes, flexure straightens protruding the penis AP text page 94 Preputial ring Stallion Mushroom shaped glans with collum glandis, corona and urethral process with small urethral sinus. Telescopes - preputial ring sits in the preputial opening in the non erect penis. Urethral sinus Inner fold of prepuce Glans Collum glandis Outer fold of prepuce Corona glandis (swab CEM) Fossa glandis Urethral process (within fossa glandis) Sigmoid flexure BULL Glans penis – Asymmetrical and twisted Retractor penis muscle Fibroelastic Sigmoid flexure straightens during erection Glans – dorsoventrally flatterned and slightly twisted ‘Broken Penis’ Reflected prepuce Tuberculum Spongiosum Urethral Process Urinary stones RAM Fibroelastic penis Large glans penis, a long worm- like urethral process Tuberculum spongiosum (bulge of corpus spongiosum) Sub urethral Diverticulum BOAR Fibroelastic penis No glans penis During erection, the free end becomes spirally twisted and engages with the sow’s cervix during copulation ACCESSORY SEX GLANDS ACCESSORY SEX GLANDS AP text page 87 Function – Produce seminal fluid to act as a transport medium aiding motility and nourish sperm Four accessory glands Prostate (6) Ampulla (4) Vesicular glands (5) Bulbourethral glands (7) Benign Prostatic Hyperplasia Testosterone driven enlargement of the canine prostate Courtesy of Lindsey Gould – University of Bristol Stallion Bull Boar Dog INNERVATION Sympathetic – Hypogastric nerve Parasympathetic – Pelvic nerves Somatic – Pudendal nerve You should now understand the following structures, their comparative anatomy and their clinical significance: Testicle Penis Accessory Sex Glands