Human Reproduction - Male Reproductive System

Primary Sex Organs: * Definition: These are organs specifically involved in the production of gametes as well as the secretion of sex hormones. * Examples in Males: Testis. Its functions include the production of sperm and the secretion of hormones like Testosterone (a type of Androgen). * Examples in Females: Ovary. Its functions include the production of ova (eggs) and the secretion of hormones like Estrogen and Progesterone.
Secondary (Accessory) Sex Organs: * Definition: These organs do not produce gametes but support reproduction by assisting in the transfer or transport of gametes, providing sites for fertilization, or providing sites for implantation. * Examples in Males: Vas deferens, Epididymis, Seminal vesicles, etc. * Examples in Females: Uterus, Fallopian tubes, Vagina, etc.

Spermatogenesis (Males): * Onset: It begins at puberty, typically between the ages of $10\text{-}14\,\text{years}$ . * Regulation: Occurs under hormonal influence. * Duration: It is a continuous process that persists even in older men.
Oogenesis (Females): * Onset: It initiates during embryonic life (before birth). * Termination: It stops at the age of Menopause, which is the cessation of the menstrual cycle/periods, typically occurring around the age of $50\,\text{years}$ .

Location: The system is situated in the pelvis region.
Components: * Primary Sex Organs: A pair of Testes. * Accessory Ducts: Includes the Rete testis, Vasa efferentia, Epididymis, and Vas deferens. * Accessory Glands: Includes the Seminal vesicle (paired), Prostate (single), and Bulbourethral gland (paired). * External Genitalia: Includes the Scrotum and the Penis.

The Scrotum: * Definition: A pouch in which the testes are located, situated outside the abdominal cavity. * Thermoregulation: The scrotum maintains a temperature that is $2\text{-}2.5\,^\circ\text{C}$ lower than the normal internal body temperature. This lower temperature is absolutely necessary for the process of spermatogenesis.
Testicular Descent and Clinical Notes: * Gestation Timeline: Testes normally descend from the abdominal cavity into the scrotum during the $7\text{th}\,\text{month}$ of gestation. * Inguinal Canal: The canal that connects the abdominal cavity with the scrotum. * Cryptorchidism: A medical condition characterized by the failure of one or both testes to descend into the scrotum.
Physical Dimensions of the Testis: * Shape: Oval. * Length: Approximately $4\text{-}5\,\text{cm}$ . * Width: Approximately $2\text{-}3\,\text{cm}$ . * Covering: Each testis is protected by a dense covering.

Testicular Lobules: * Each testis is internally divided into approximately $250$ compartments called testicular lobules.
Seminiferous Tubules: * Each lobule contains $1\text{ to }3$ highly coiled seminiferous tubules. * These tubules are the specific site where sperm are produced. * Internal Lining (Cell Types): * Male Germ Cells (Spermatogonia): These cells undergo meiotic divisions, eventually leading to the formation of sperm. * Sertoli Cells: These provide essential nutrition and support to the developing germ cells.
Interstitial Space: * The regions located outside the seminiferous tubules are known as interstitial spaces. * Interstitial Cells (Leydig Cells): These cells synthesize and secrete testicular hormones called androgens (primarily testosterone). * Other Components: The interstitial spaces also contain small blood vessels and immunologically competent cells.

Duct Hierarchy and Pathway: 1. Seminiferous Tubules: Site of sperm production. 2. Rete Testis: A network of tubules that receives sperm from the seminiferous tubules. 3. Vasa Efferentia: Ducts that carry sperm from the rete testis to the epididymis. 4. Epididymis: Located along the posterior surface of each testis; it stores sperm and leads to the vas deferens. 5. Vas Deferens: This duct ascends into the abdominal cavity and loops over the urinary bladder. 6. Ejaculatory Duct: Formed by the union of the vas deferens and the duct from the seminal vesicle. 7. Urethra: Originates from the urinary bladder, receives the ejaculatory duct, and extends through the penis to the external opening.
Function: These ducts are responsible for the storage and transport of sperm from the testes to the exterior of the body.

Penis: * This is the male external genitalia. * Glans Penis: The enlarged, distal (front) part of the penis. * Foreskin (Prepuce): A loose fold of skin that covers the glans penis.
Urethra: * Urethral Meatus/Orifice: The external opening of the urethra through which urine and semen exit the body.

Question 1: Urethra originates from? * A) Penis * B) Urinary bladder * C) Seminal vesicle * D) Testis * Answer: B) Urinary bladder.
Question 2: The role of the primary sex organ is: * 1) Production of gamete * 2) Transport of gamete * 3) Production of hormone * 4) Both 1 and 3 * Answer: 4) Both 1 and 3.
Question 3: Vas deferens receives a duct from the seminal vesicle to form the common ejaculatory duct and this opens into: * A) Ureter * B) Urethra * C) Seminal vesicle * D) Scrotum * Answer: B) Urethra.
Homework Assignment: * Refer to Module Page Number 5, "Check Your Understanding-1", Questions 1 through 9.