Mammalian Reproductive System
Most mammal reproductive systems are alike; however, there are a few prominent differences between the "normal" mammal and humans. For example, the majorities of mammalian males have a penis which is stored internally until erect, and a few have a penis bone or baculum.
Furthermore, males of the majority species do not remain continually sexually fertile as humans do.
Like humans, the majority of mamalian groups have descended testicles located inside the scrotum, on the other hand, others have goes down testicles that relax on the ventral body wall, and other groups of mammals, like elephants, have undescended testicles are located deep within their body cavities close to their kidneys.
General Functions of the Female Reproductive System
The female primary reproductive organs are the ovaries. The functions of the ovaries include the production of female sex hormones and oocytes as well as secretions by glands in the reproductive system.
The accessory ducts include the uterine tubes, where fertilization takes place; the uterus, where the embryo grows; and the vagina, which serves as a birth canal and receives the penis during sexual intercourse.
In amniotes, fertilization is normally internal, with sperm transfer irregularly assisted by a male intromittent organ. In placental mammals, the reproductive structures have become well developed and specialized to make the act of giving birth possible.
Methods of Reproduction in Mammals
The three types of mammals differ in their methods of reproduction.
• Placental Mammals such as the cat are viviparous. Viviparity, or birth of live young, has separately evolved more than one hundred times in vertebrates. Nevertheless, a lot of vertebrates retain the shelled egg laying method of giving birth as a result of the nutrients made available by the shell and passed to the embyo.
• Monotremes are the most primitive types of mammals. They have maintained the reptilian oviparous method of reproduction and lay shelled eggs.
• Marsupials go through a fuzzy type of viviparity. They give birth to underdeveloped live young. When the young are born, they move to the permanent brood pouch, or marsupium. Development of the young is finished in the pouch.
Female Reproductive Structures In Mammals That Allow Viviparity
Ovary: The ovary is paired, almond-shaped organs that are propped up by the mesovarium, a part of the broad ligament. The ovary is the place of oogenesis and hormone production.
Oviducts: The oviducts are as well regarded as the uterine tubes. They receive the oocyte and make available a site for fertilization.
Infundabulum: This is the sideways part of the oviduct that lokes an open funnel. This feature is covered with ciliated and finger-like projections known as fimbrae which wrap over the ovary. The movements of the fimbrae brush the oocyte into the tube.
Ostium Tubae: The infundabulum unlocks medially through the ostium tubae.
Uterus: The oviducts come together into the bigger uterine horn. The two uterine horns mingle to form the uterine body. The entire structure is Y-shaped.
The mammalian uterus has developed a highly vascularized lining whose function is to receive, retain, and nourish a fertilized egg all through pregnancy.
During the pregnancy, the uterine horns block up the abdominal cavity. The other organs are pressed in all directions to give room to the developing fetus.
Vagina: The vagina is a thin-walled tube that is located posterior to the uterus. It makes a tube for the delivery of an offspring.
Evolution of a Secondary Sexual Characteristic
Mammary glands are unique to living mammals. They are formed from specific skin glands. Mammary glands play a role in lactating females when they produce milk for the nourishment of an offspring.
Female mammals are born with all the follicles they're ever going to have, and every one of the follicles possesses a primary oocyte. There are significant numbers of these. In humans the total number of primordial follicles present at birth can be up to 500,000 or more.
They are normally dormant until the stage of puberty. Hormonal changes that take place in the body at this stage will cause the eggs to get up from their dormant state. However, just a few among those thousands of egg would mature to the stage of ovulation.
Human beings possess a much longer reproductive life than the majority of other mammals, but even at that if a woman ovulates once every month from the ages of 12 to 50, she can only produce about 400-500 matured eggs that capable of being fertilized. That is one tenth of one percent of her total follicles.
Human Reproductive System
The human reproductive system is normally composed of internal fertilization through the process of sexual intercourse. During this process, the erect penis of the male is inserted into the female's vagina until the male ejaculates semen, which is composed of sperm, into the female's vagina.
The sperm afterwards travels through the vagina and cervix into the uterus or fallopian tubes for fertilization of the egg.
Upon successful fertilization and implantation, gestation of the fetus then occurs inside the female's uterus for just about nine months, this process is referred to as pregnancy in humans. The process of gestation comes to an end with birth. The process of giving birth is referred to as labor.
Labor results as a result of the contraction of the muscles of the uterus, the dilation of the cervix and the passage of the baby through the vagina which is the woman’s reproductive organ.
Human's babies and children are almost defenseless and need and require high levels of parental care for lots of years. One major crucial type of parental care is to make use of the mammary gland to nurse the baby.
The female reproductive system has two-fold functions: To produce egg and to protect and look after the offspring until birth. The male reproductive system has one function, which is to produce and to dump sperm.
Humans have a lofty level of sexual differentiation added to the variations in roughly every reproductive organ, a lot of variation normally take place in the humans during the development of the secondary sexual characteristics.
Male Reproductive System
The male reproductive system is composed of organs situated outside of the body and around the pelvis region of a male which plays a role in the reproduction process. The major express function of the male reproductive system is to make available the male sperm for fertilization of the ovum.
The major reproductive organs of the male can be classified into three categories. The first category is sperm production and storage. Production of sperm occurs in the testes which are housed in the temperature regulating scrotum, immature sperm then journey to the epididymis for development and storage.
The second category is the ejaculatory fluid producing glands which are the the seminal vesicles, prostate glands, and the vas deferens. The last category is those employed during copulation, and deposition of the spermatozoa (sperm) within the male. They include the penis, urethra, vas deferens, and Cowper's gland.
The main secondary sexual characteristics of males include: larger, extra muscular stature, deep voice, facial and body hair, broad shoulders, and development of an adam's apple. A crucial sexual hormone of males is androgen, and especially testosterone.
The testes release a hormone that regulates the development of sperm. This hormone is as well responsible for the development of physical characteristics in men like facial hair and a deep voice.
Human Female Reproductive System
The human female reproductive system is a succession of organs principally situated in the interior part of the body and just about the pelvic region of a female which plays a role in the reproductive process.
The human female reproductive system is composed of three major parts: the vagina, which leads from the vulva, the vaginal opening, to the uterus; the uterus, which holds the developing fetus; and the ovaries, which produce the female's ova.
The breasts are involved during the parenting stage of reproduction, but in the majority of classifications, they are not regarded as part of the female reproductive system.
The vagina opens up on the outside through the vulva, which as well contains the labia, clitoris and urethra; during intercourse this area is greased by mucus secreted by the Bartholin's glands.
The vagina is attached to the uterus via the cervix, while the uterus is attached to the ovaries through the fallopian tubes. Each one of the ovaries possesses hundreds of egg cells or ova (singular ovum).
Roughly every 28 days, the pituitary gland releases a hormone that stimulates some of the ova to enlarge and grow. One ovum is released and it passes through the fallopian tube into the uterus.
Hormones manufactured by the ovaries get the uterus ready to receive the ovum. The lining of the uterus, known as the endometrium, and unfertilized ova discharged every cycle via the process of menstruation. If the ovum is fertilized by sperm, it attaches to the endometrium and the fetus develops.
Production of Gametes: Spermatogenesis and Oogenesis
The production of gametes takes place inside the gonads via a process referred to as gametogenesis. Gametogenesis takes place when certain types of germ cells undergo a cell division known as meiosis to divide the standard diploid number of chromosome (n=46) into haploids cells which contains only 23 chromosomes.
In males, this process of gamete production is referred to as spermatogenesis and occurs only after puberty the seminiferous tubules of the testes. The immature spermatozoon or sperm are then sent to the epididymis where they gain a tail and motility.
Each of the original diploid germs cells or primary spermatocytes forms four functional gametes which is each forever young. The production and survival of sperms require a temperature that is lower than the normal core body temperature.
Since the scrotum, where the testis is present, is situated outside the body cavity, it provides a temperature about 3°C below normal body temperature.
In females, gametogenesis is known as oogenesis which takes place in the ovarian follicles of the ovaries. This process does not generate mature ovum until puberty.
As opposed to the situation in males, every one of the new diploid germ cells or primary oocytes will form only a single mature ovum, and three polar bodies which are not able to be fertilized.
It has long been understood that in females, different from what is obtained in males, every one of the primary acolytes ever found in a female will be created before birth, and that the final stages of ova production will then not start until puberty.
However, current scientific data has challenged that hypothesis. The fresh data shows that in at least a number of species of mammal oocytes carry on replenishing in females a long time after birth.
Examples of related human reproductive organs
Male organ Female organ Shared function
Cowper's gland Bartholin's glands Lubrication secretions
Penis Clitoris Erectile tissue and sensation
Testes Ovary Gamete production
Prostate gland Skene's gland Ejaculatory fluid and sensation
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