Female and Male reproductive organs

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Female reproductive organs


•      The female reproductive tract has two major components:
1.     The ovaries:
•      produce the mature ovum
•      Secrete progestins, androgens, and estrogens.
 2. The ductal system:
•       transports ovum
•      is the place of the union of the sperm and egg and maintains the developing conceptus until delivery.

The essential female reproductive functions
1. Production of ova (oogenesis)
2. Reception of sperm
3. Transport of the sperm and ovum to a common site for union (fertilization, or conception)
4. Maintenance of the developing fetus until it can survive in the outside world (gestation, or pregnancy), including formation of the placenta, the organ of exchange between mother and fetus
5. Giving birth to the baby (parturition)
6. Nourishing the infant after birth by milk production (lactation)

•      The normal reproductive years of the female are characterized by monthly rhythmical changes in the rates of secretion of the female hormones and corresponding physical changes in the ovaries and other sexual organs.
•      This rhythmical pattern is called the female monthly sexual cycle (or, less accurately, the menstrual cycle).
•      The duration of the cycle averages 28 days.
•      It may be as short as 20 days or as long as 45 days in some women.
•      There are two significant results of the female sexual cycle.
•      First, only a single ovum is normally released from the ovaries each month, so that normally only a single fetus will begin to grow at a time.
•      Second, the uterine endometrium is prepared in advance for implantation of the fertilized ovum at the required time of the month.

Hormonal Control of  Female Reproductive Functions



Male reproductive system


Anatomy
•      The male reproductive system includes:
1.      the two testes,
2.      the system of ducts that store and transport sperm to the exterior
3.     the glands that empty into these ducts, and the penis. The duct system, glands, and penis constitute the male accessory reproductive organs.

The testes

•      The testes are suspended outside the abdomen in the scrotum, which is an outpouching of the abdominal wall and is divided internally into two  sacs, one for each testis.
•      During fetal development, the testes are located in the abdomen, but during the seventh month of intrauterine development, they descend into the scrotum. 
•      This  descent  is  essential  for  normal  sperm production during adulthood, since sperm  formation requires a temperature several degrees lower than normal internal body temperature.
•                   Cooling is achieved by air circulating around the scrotum  and  by  a  heat- exchange mechanism  in  the  blood  vessels  supplying the testes.
•                  In contrast to spermatogenesis, testosterone secretion can usually occur normally at internal body temperature, and so failure of testes descent does not impair testosterone secretion.
•      The sites of sperm formation, or spermatogenesis are the seminiferous tubules.
•      The  cells  that  secrete  testosterone are Leydig cells

The glands

•      The prostate gland and seminal vesicles secrete the bulk of the  fluid  in which  ejaculated  sperm  are  suspended.
•      This fluid, plus the sperm cells, constitute semen.
•      The glandular secretions contain a large number of different chemical substances, including:
1.      nutrients,
2.      buffers for protecting the sperm against the acidic vaginal secretions,
3.     chemicals (particularly from the seminal vesicles) that increase sperm motility, and
4.     prostaglandins. 
•       The bulbourethral glands contribute a small volume of lubricating mucoid secretions.

Functions of Sertoli cells


Mullerian inhibiting substance (MIS) is the gonadal hormone that causes regression of the Mullerian ducts, the anlagen of the female internal reproductive structures, during male embryogenesis.

. Mullerian inhibiting factor (MIF), also called the anti-Mullerian hormone (AMH) plays a significant role in sexual differentiation. It is produced by the Sertoli cells in male fetuses and signals the regression of the Mullerian ducts, fallopian tubes, and uteru.


Hormonal Control of Male Reproductive Functions


•      Testosterone doesn’t affect hypothalamus and GnRH directly but it affects Kiss 1 neuron in ARC arcuate nucleus which inhibit the secretion of Kisspeptin that inhibit the secretion of GnRH   


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