Role of the male Produce ample amounts of viable sperm Willing and able to deliver semen (containing sperm) –to female –to AI
Anatomy of MALE Paired TESTES Epididimyis Vas deferens Penis Scrotum Accessory Sex Glands
Scrotum Testes descend from near kidney at or near birth –failure: monorchid or chryptorchid Maintains temp 4-8° cooler than body
Temp regulation in testes External Cremaster muscle –contracts when cold, relaxes when warm tunica dartos (smooth muscles in skin) –contract when cold pampiniform plexus heat exchanger in blood above testicle esp. stallion & boar
The major species differences are related to which accessory sex glands are present and the structure of the penis.
Spermatogenesis occurs within the seminiferous tubules of the testes under the metablic and hormonal support of sustentacular and interstitial cells (Sertoli’s cells). Sperm are stored and mature in the epididymes until resorption or ejaculation.
Sperm are produced continually in great numbers –Bull = 5 BILLION sperm per ejaculate Regulated by FSH Cells of Leydig secrete testosterone –Regulated by LH
Secretions of the accessory glands contribute to the formation of the semen. The penis contains vascular and connective tissue specializations to produce erection which facilitates intromission.
The mammalian male reproductive tract consists of the testes, a duct system, and related glands.
Testes & epididymis Sperm are produced in the testis and mature in the epididymis.
Ductus deferans (vas deferens) The ductus deferens (vas deferens) propel sperm to the urethra during ejaculation.
Ampulla The ampulla is a glandular region of the terminal portion of the ductus deferens. It is absent in cats and pigs.
Prostrate The prostate gland empties into the urethra. It provides the bulk of seminal fluid in most species.
Vestibular glands (Seminal vessicles) The vestibular glands vary greatly in size depending on the species. They are absent in canines and felines.
Bulbourethral gland The bulbourethral glands are present in the pig, equine and bovine, but missing in the canine.
Penis Varies by species - Horse: erectile tissue, blood engorgement, Ram & boar: less erectile tissue. Sigmoid flexure.
Dog penis Os penis Urethra Blood sinuses
Testis Seminiferous tubules form the mass of the testes and are the sites of spermatogenesis.
Testis Head of Epididymis Tail of Epididymis
Spermatogonia The spermatogonia are the germ cells of the testis. Unlike mamallian oogonia, they continue to divide throught life.
Primary spermatocytes The spermatogenic cells--spermatogonia, primary spermatocytes, secondary spermatocytes, spermatids and spermatozoa--represent different cell stages in spermatogenesis.
Sustenticular cells The outlines of sustentacular cells are not distinct. Maturing spermatozoa are found embedded, head first, in the sustentacular cells, which provide mechanical support, protection and possibly nutrition for the developing spermatozoa.
Factors affecting sperm production Sexual maturity Heredity Underfeeding Nutrients like Vitamin A, E, protein Temperature Testis size Abnormalities
Male Review Spermatogenesis occurs in the seminiferous tubules of the testes. –Sustentacular and interstitial cells aid the development of spermatogonia into spermatozoa with a nuclear head, mitochondria filled midpiece and a microtubule tail.
Sperm are stored and mature as they move through the head, body and tail of the epididymis and into the ductus deferens. Seminal fluid is formed by the addition of nutrients, buffers and lubricants from the accessory sex glands –(e.g. vesicular, bulbourethral, prostate and ampulla.
There is variation among species as to which glands are present. The penis may contain an os penis in addition to vascular sinuses, (corpus spongiosum and cavernosum) to produce erection. The urethra is also shared by the urinary tract.