Human Reproductive System

THE MALE REPRODUCTIVE SYSTEM

The male reproductive system consists of a pair of testes lying in the scrotal sacs (scrotum) which are attached to the lower anterior wall of the abdomen. During the early embryonic development of a male, the testes are located in the body cavity. But, before birth, the testes descend into the cavities of the scrotum through a tube called the inguinal canal which is a connection between the scrotum and the body cavity. The canal gets blocked by connective tissue after the testes descend. The reason for the testes’ descent is that the sperms produced by the testes survive and mature in the cooler temperature of the scrotum and not with the internal body temperature in the body cavity.

Each testis contains 1,000 coiled tubules called the seminiferous tubules which actually produce the sperms. Cells called the sertoli cells (nurse cells) nourish the developing sperm.

The seminiferous tubules open into fine tubes called the vasa efferentia (or efferent ductules or ductus efferentes). The vasa efferentia join to form a long, highly coiled tube called the epididymis where the sperms are stored. (The epididymis is derived from the embryonic kidney.) The epididymis looses its convolution and continues as a long tube called the vas deferens (ductus deferens). The vas deferens passes from the scrotum through the inguinal canal, into the abdominal cavity and over the urinary bladder to a point where it joins the duct of an accessory sex gland called the seminal vesicle to form a short ejaculatory duct. The seminal vesicle secretes a fluid which forms a major part of the semen. The ejaculatory duct opens into the urethra which is a tube that continues from the urinary bladder to the exterior. The urethra in males passes through the male copulatory organ called the penis.

The urethra is differentiated as the prostatic urethra, membranous urethra and the cavernous urethra. The prostatic urethra is a part of the urethra surrounded by an accessory sex gland called the prostate found below the bladder. The prostate secrets a thin, milky, alkaline fluid that forms a part of the semen. The membranous urethra is a part of the urethra surrounded by a membrane called the urogenital membrane. Lying on either side of the membranous urethra are a pair of pea sized glands called the bulbo-urethral glands (Cowper’s glands). They open into the cavernous urethra and secrete a fluid which forms a little part of the semen. The cavernous urethra is a part of the urethra that passes through the corpus cavernosum and the corpus spongiosum of the penis.

THE FEMALE REPRODUCTIVE SYSTEM
The female reproductive system consists of a tube-like muscular passage called the vagina which is surrounded by the labia majora and the labia minora. The labia majora is a fatty tissue of two folds covered by skin with hair while the labia minora is a thin fold of tissue devoid of hair. The labia majora conceals the labia minora. At the ventral junction of these two is a sensitive, erectile organ called the clitoris, which is a major site of female sexual excitement.

The vagina is lined by mucosa which is moistened by secretions from the uterus. The vagina extends from the exterior to a hollow, thin-walled muscular structure called the uterus. The muscular ring of the uterus which projects into the vagina is called the cervix.

The uterus continues into the fallopian tubes (or oviducts or utrine tubes) which are about 10 cm in length and differentiated as the isthmus and the ampulla. The ampulla ends in a funnel-like structure called the infundibulum formed by branched processes called fimbriae. The fimbriae spread over the ovary and help in picking up the ovum at ovulation.

The ovaries are the main reproductive organs found attached to the posterior side of the broad ligament of the uterus by a short fold called the mesovarium.