welcome to module 8. this part of the lecture will discuss the basic gross anatomy of the male reproductive system this is the first part of the two modules on the reproductive system ideally this presentation can be divided into four main parts the male gonads where the male gametes are being formed the ducks at which the gametes travel to be released outside of the body the copulatory organ used by the male animals for copulation and then the accessory sex glands an understanding of the chronological order of the system parts is essential to appreciate the anatomy of the male reproductive system at the end of this module you should be able to identify the organs and associated structures in the male reproductive system and at least trace the track of the spermatozoa from the testis to the penis the reproductive system is important for the perpetuation of life male and female animals have different anatomical structures but with almost the same function the system has garnets that produce the sex-specific gametes and male has the testis producing the spermatozoa at a mature age the system is provided with drugs enabling the maturation of such gametes in addition male has accessory sex glands that nourish the developing spermatozoa the system has structures that enable the meeting of these gametes for fertilization in this module we will tackle the different parts of a male reproductive system which include the scrotum testis epididymis the ferrent duck the spermatic cord the prostate and the penis let us begin with the scrotum the scrotum is a pouch of skin where the testes are located it lies between the thighs and the left is farther codally than the right it is pigmented and covered with fine hairs the scrotum is divided by a scrotal septum made up by all scrotal tissues except the skin here is a cross section of a testicle let us highlight the layers of the scrotum and note that it is composed of several structures the skin is the outermost layer and is usually pigmented next to the skin is the tonica dartos this is a layer of smooth muscle deep to the skin contraction of this muscle draws or retracts the scrotum close to the body this is the reason why the scrotum has a wrinkled appearance the spermatic fascia is composed of the external and internal spermatic fascia the external spermatic fascia is an extension of the external abdominal oblique fascia while the internal spermatic fascia is an extension of the transversus abdominis fascia remember that the said muscles were parts of the abdominal muscles also included in some textbooks is the treemaster muscle this is an extension of the internal abdominal oblique muscle this is important in the thermoregulation of the testis this muscle pulls the testicle towards the body when the environmental temperature is cold and otherwise moves away from the body when it is hot in this slide you can also see the testes the different blocks like the epididymis and the ductus deferens as well as the scrotal septum separating the right and left testicle inside the scrotum is the test test the testis is the male gonad producing the male gametes called spermatogonia aside from this the leading cells inside the testis is producing testosterone a hormone responsible for the male behavioral and physical characteristics during the embryonic development the testis is located at the abdominal area of the developing fetus but during the course of the development the testis is pulled towards the adult position inside the scrotum the developing organs in the abdominal area push the testis out of the cavity this is called the descent of the testis this exit is being guided by a structure called the gobernakilum this descent of the testis happened in carnivores like dogs shortly after birth here is the gross appearance of the testis after the removal of the scrotum the white covering of the testis is called tunica albuginea which we will discuss in the next slides now let us study further the parts of a testis the parts can be divided into a connective tissue component and the parenchyma itself the connective tissue are basically for support function while the parenchyma is the actual structures that perform the actual function of the testis the connective tissue component is composed of the tunica albuginea the septa and the mediastinum the tunica albuginea or the white tunic is a strong white fibrous capsule enveloping the testis the lobules on the other hand are the units of testicles which contains few seminiferous tubules they are separated by a connective tissue called septa the mediastinum testis is the cord of fibrous tissue running through the midline of the testicle containing the retta testis again the function of these connective tissues are for support and compartmentalization of the parenchyma of the testis the parenchyma on one hand is the actual structures important for the function of the testis itself this is composed of the tubules and ducts where the spermatozoa pass through physiologically the location of the spermatozoa within the ducts suggests its maturity thus it is important to trace the chronological order of the ducts the parenchyma is composed of the seminiferous tubules the red etestis and the efferent ducts seminiferous tubules are hollow structures in which male germ cells differentiate into spermatozoa grossly the seminiferous tubules can be divided into two the convoluted seminiferous tubules and the straight seminiferous tubules the convoluted seminiferous tubule is the actual site of sperm production histologically here is the appearance of the seminiferous tubules showing the different stages of spermatozoa close to the wall of the tubules are the primary spermatogonium as they move to the lumen they mature into secondary spermatogonia spermatids and at the lumen itself is the spermatozoa you will learn more about this on your histology and embryology courses the straight seminiferous tubules on the other hand are short straight part near the medyastinum and they do not produce the sperm the red testis is a network of irregular interconnecting channels continuing as the straight seminiferous tubules through the mediastinum to the efferent duck the red testes will become the efferent duck there are around 8 to 15 channels leading into the head of the they unite to form the epidermis the efferent duck will continue as the epidermal duct the epidermis is the structure closely adjacent and attached to the testis it has the following parts the head is consist of the efferent ducts the body or the central part consisting of highly coiled epidimal duct connecting the head and the tail and the tail which is the bulbous end and continuous as the ductus deferens please take note as well the ligaments attaching the tail of the epidermis to the testis and the vaginal process the proper ligament of the testis attached caudal testis with the tail of the epididymis on the other hand the ligament of the tail of the epidermis attached the tail of the epididymis to the vaginal process the deferent duck or the vas deferens is the direct continuation of the epidermal duct the urethra now let us review the order of the ducts from the seminiferous tubules to the red testis to the efferent duck epididymal duct the ferrent duck and finally the urethra the spermatic cord is the structure composed of the vas deferens the testicular artery testicular veins testicular nerves and lymphatics and their serous coverings the structure extends from the testicle through the inguinal canal this is one of the structures being ligated during castration the vaginal tonic is a double wall of serous membrane around the spermatic cord and the testicle the one covering the testicle directly is the visceral vaginal tunic while the opposite side is the parietal vaginal tunic the space between the two is called the vaginal cavity this cavity is continuous with the peritoneal cavity at the vaginal ring the vaginal ring is a crescent shaped opening located on the abdominal side of the deep inguinal ring it is also important to note some anatomical arrangement in the male reproductive tract that has important role in the thermoregulation for the maintenance of the sperm this is the pumpini form plexus it is a coil of testicular veins and testicular artery making the bulk of the spermatic cord it functions to draw heat from the testicular artery cooling the blood before it reaches the testis take note that the venous blood is cooler than the arterial blood thus because of the conduction mode of heat transfer the warm arterial blood is being cooled by the cooler venous blood before it supply the testis the accessory sex glands add liquid portion to the ejaculate it provides around 95 to 98 percent of the total ejaculate volume in most domestic animals there are four known accessory sex glands that include the prostate gland the bulbourethral gland the vesicular gland and the ampullaric gland however in dogs only the prostate gland is present other references indicate the presence of the ampullary gland the prostate gland as you can see here is completely enveloping the proximal portion of the male pelvic urethra at the neck of the bladder the prostate is bounded dorsally by the rectum and ventrally by the symphysis pubis and ventral abdominal wall the function of the prostate is not entirely understood the penis is the copulatory organ of the male extending from the skiatic arc cranially between the thighs it provides a passageway for semen and urine to the outside of the body thus it is both part of the urinary and the reproductive system it originates as two crora that converge to form the root of the penis which continues as the body of the penis to the glands of the penis there are two main types of penis in the animal the musculocavernous type of penis contains a lot of erectile tissue and little connective tissue thus during erection there is both an increase in the length and diameter of the penis the cavernous tissue contains large blood spaces divided by thin septa therefore a relatively larger volume of blood is required to achieve erection this type of penis is present in man stallion tomcat and in male dogs on the other hand the fibroelastic type penis contains large amount of connective tissue and elastic fibers but limited erectile tissue it contains a sigmoid flexure and most of the increase in the penile length is actually due to the straightening of the sigmoid flexure this type of penis is present in male ruminants like bull buck and rum as well as in male pig cold bore again the penis of dog is classified as muscular cavernous type the penis is composed of three columns of erectile tissue the paired corpus cavernosum is located dorsally and the unpaired corpus spongiosum is located ventrally the corpora cavernosa made up the dorsal column of the penis as you can see here while the corpus spongiosum provides the ventral column it is more delicate with larger blood spaces let us again check this slide to see the other structures present in the penis the prepuce is the cutaneous sheath around the free part of the penis in the non-erect state it has an inner lamina which is continuous with the skin over the gland's penis and an outer lamina continuous with the skin on the abdomen the prepucial orifice is the opening of the prep used to the outside the os penis or bakulum is found on the penises of carnivores in dogs the ventral surface is grooved for the urethra as you can see here the bulbous glandis is the part of the gland's penis surrounding the proximal os penis together with the female dog or [ __ ] vestibular bulb this is responsible for the coital lock in dogs also take note here the location of the prostate gland once this gland enlarged in the case of a tumor the urine flow will be blocked thus there will be difficulty in urination and that ends our discussion on module 8. after finishing this lecture you are now ready to take the assessment prepared for the