Category: Reproductive Health

Ovarian surface epithelium (OSE) cells, derived from mesodermal epithelium of gonadal ridges, are flattened mesothelium of peritoneum separated from underneath ovarian stroma by a basement membrane and a connective tissue layer, tunica albuginea (Leung & Choi, 2007). OSE occupies the entire ovarian lining and varies in morphology from simple squamous to cuboidal to low pseudostratified columnar. OSE participates in transporting and exchanging nutrients and other bioactive metabolites from the peritoneal cavity and ovary.

Despite their inconspicuous appearance, OSE actively participates in the ovulatory cycle. Studies in rabbits and sheep have revealed that OSE produces proteolytic enzymes that degrade the basement membrane and apical follicular wall thereby softening the ovarian surface and facilitating ovulation. At pre-ovulation, OSE in proximity to the rupture site undergoes apoptotic cell death, and the wound caused by ovulation is repaired by highly proliferating OSE cells from the surroundings of the ruptured follicle. OSE cell proliferation also occurs at the post-ovulatory phase especially in a post-menopausal woman when due to aging of the ovary; the epithelial line invaginates, producing crypts and glands, which eventually develop into cysts within the stromal compartment.

Although mostly benign, these cysts can turn malignant and initiate epithelial cancerous growth. Approximately 90% of human ovarian cancer origin from OSE, whereas follicular granulosa cells (GC’s), stroma, or germ cells account for the rest of the incidences (Vanderhyden, Shaw & Ethier, 2003). Epithelial ovarian cancer is the fourth most common cancer in females around the world and the most lethal gynecological malignancy. It has been hypothesized that repeated cycles of ovulation-induced trauma and repair of the OSE at the site of ovulation contribute to malignancy. A host of tumorigenesis factors, viz. cytokeratin, desmoplakin, transforming growth factor-α (TGF-α) and receptors for estrogen, progesterone and epidermal growth factor (EGF) are expressed by OSE.

The “incessant ovulation hypothesis” proposes that repeated ovulations and concomitant ovarian surface rupture and OSE mitosis to heal the wound, makes the OSE susceptible to mitogenic factors and other genotoxic radicals. It is well known that pregnancy and use of oral contraceptives can reduce the risk of epithelial ovarian cancer (EOC) development. Additionally, it has been reported that EOC is absent in animal species where seasonal ovulation and multiple pregnancies take place. Suppression of ovulation and steroid production by the pre-ovulatory follicles are the main significant alteration that occurs within the ovary during pregnancy.

Although pregnancy is proposed as protective factor against ovarian cancer, the mechanism by which it may enhance this effect is not elucidated. Rodent’s isolated OSE cells, continuously maintained in proliferative conditions, after several rounds of subcultures acquired malignant features including loss of contact inhibition, substrate-independent growth and the ability to form tumors in nude mice. Suitable animal models in which OSE undergoes in vivo transformation to neoplastic state would be highly useful for investigating cellular changes attributed to this phenomenon, as well as for developing diagnostic, preventive and even curative measures.

According to Fortune (1994) senescent ovary, like the one during pregnancy or postnatal period, maintains oocytes in “resting” or primordial follicles. Growing follicles either ovulate to release oocytes for fertilization, or degenerate through into atretia. Differentiated follicles also provide steroidal hormones to maintain the ovarian cycle and prepare uterus for implant, and CL produces hormones for establishing and maintaining pregnancy. Gondotropins and estrogens are vital for maintaining ovarian cycle until antral stage just before ovulation. Early follicular growth and development occur readily in the presence of normal basal concentrations of gonadotropins.

In cycling mammals upon reaching 8-9 GC stage the primordial follicles start to grow to large antral follicles in two different patterns – in rats, primates and pigs, in follicular phase only one follicle grows and others in cohort regress, and in cattle, sheep and horses, a wave of 3-6 follicles continue to grow in follicular as well as luteal phases and one of them slightly larger than others continues to grow while the other subordinate follicles regress. Recent evidences suggest that FSH in combination with TGF-β1 mediates follicular progression and associated proliferative activities in GC’s beyond primary and preantral stages, and this involves an increase in apoptosis and suppression of subordinate follicle development (Findlay et al. 2009).

In this study, we have examined proliferative activity of OSE and granulosa cells of the ovarian follicles by immunohistochemistry (IHC) of proliferating cell nuclear antigen (PCNA) and Ki67 proteins, which is a standard method for detecting proliferating cells in tissue sections. Additionally, a histomorphological study was done to identify the stages of follicular development at different phases of the reproductive cycle, including the quiescence phases (anoestrous and pregnancy).

We have selected sheep as in vivo model for two reasons: a) sheep is a mono-ovular and seasonally polyoestrous animal, with ewes being short-day breeders. Ovulatory cycles in most sheep breeds in the northern hemisphere, occur in a regular pattern between autumn and winter with oestrous cycle that ranges in length from 14 to 18 days. Ewes exhibit an anoestrous phase that starts from the end of spring until the start of summer, and b) as research material more than one differentiated follicles of the intermediate stages like primary, preantral and antral follicles can be obtained in estrous phase, which is not possible in case of human ovaries.

References

Findlay, J.K., Kerr, J.B., Britt, K., Liew, S.H. Simpson, E.R. Rosairo, D. & Drummond, A. (2009). Ovarian physiology: follicle development, oocyte and hormone relationships. Animal Reproduction, 6(1), 16-19.

Fortune, J.E. (1994). Ovarian Follicular Growth and Development in Mammals. Biology of Reproduction, 50, 225-232.

Leung, P.C.K. & Choi, J-H. (2007). Endocrine signaling in ovarian surface epithelium and cancer. Human Reproduction Update, 13(2), 143–162.

Vanderhyden, B.C., Shaw, T.J. & Ethier, J.F. (2003). Animal models of ovarian cancer. Reproductive Biology and Endocrinology, 1:67. Web.

High proliferative activity in the ovarian surface epithelial (OSE) layer, sometimes leading to cancerous growth, is believed to be associated with multiple ovulation and the resultant mitogenic effect of hormones at the site of ovulation. Estrous (cycling), anoestrous and pregnant ewes were selected in this study to evaluate whether OSE and follicular granulocyte cells’ proliferation is affected by the reproductive stages of the animal.

For this purpose, the level of proliferation was tested immunohistochemically using two nuclear protein markers, PCNA and Ki-67. Further, based on the morphological appearance of granulosa cells, the frequency of primordial, transitory, primary, preantral, and antral follicles was determined in the three groups of animals. Photomicrographs of the OSE layer revealed disorganized cells only in estrous ewes over corpus luteum. The same group also presented high Ki-67 immunoreactivity in the OSE layer indicative of high proliferative response. PCNA staining was also detectable in the OSE layer but at all follicular developmental stages, which suggests that, unlike the Ki-67 marker, this marker does not necessarily recognize the cell multiplication-related DNA synthesis activity.

In all the reproductive groups, the granulosa cells of primary, preantral and antral but not the primordial and transitory follicles exhibited a varying degree of immunostaining with PCNA, the maximum being in cycling animals. When the Ki-67 marker was used, granulosa cells of primary follicles in the cycling, and more differentiated follicles in all the groups reacted positively. The frequency of different follicles also varied in the three groups.

While primordial and transitory follicle counts were nearly similar in each group of the animals, the frequency of preantral and antral follicles was lower in the pregnant than in the anoestrous and cycling groups. Within this low percentage to the size of the antral follicle also varied significantly in the three groups. The small antrum (<2 mm and 2-3 mm) were uniformly present in all the animals but the larger ones (3-4 and 4-5 mm) were nearly absent in the pregnant ewes.

We discussed the role of progesterone produced in the corpus luteum in suppressing follicular development during pregnancy. The antrum before maturing becomes atretic. In anoestrous ewes, estrogen may have an overriding effect on progesterone and follicular development goes on normal, especially the antrum attains normal size. It is in the cycling animals, were due to frequent ovulation, the OSE cells in proximity to ovulating follicle or post-ovulating corpus luteum exhibit massive proliferative activity and disorganized colonization. In the normal course, this may lead to epithelial regeneration in the wounded site, but if exposed to mitogenic or inflammatory agents, these cells may transform neoplastic.

The female reproductive tract is made up of fallopian tubes, uterus, ovaries and the vagina (Waters, 2008). There are various health complications which may affect these parts. Common health concerns that can affect the female reproductive tract include:

Endometriosis

Endometriosis manifests itself as abnormal growths in the uterine tissues. When a person develops this disorder, she will complain of abdominal pain. Cases of vaginal bleeding, pain when having sex, nausea and diarrhea have also been reported. Surgical operations can be used to treat this condition. Alternatively, hormone treatment may be used.

Uterine fibroids

This condition affects about 25% of women who are 50 years old and below. Uterine fibroids cause various problems. For instance, the affected person may suffer from lower back pain and menstrual bleeding. It can also result in reproductive concerns such as infertility. Individuals suffering from uterine fibroids require a lot of attention. This is because the uterine fibroids cause a lot of discomfort. The most effective treatment option for this health concern is surgery.

Ovary failure

This problem is popularly identified as premature ovarian failure. Basically, a woman who is suffering from premature ovarian failure will experience conception problems. This is because her ovaries will not be able to produce eggs. In addition, victims will experience irregularities in their menstrual cycles. Estrogen replacement is normally used as a corrective measure to this disorder.

Polycystic Ovary Syndrome (PCOS)

This problem develops when the production of androgens by the ovaries increase. When the level of androgen hormones is high, the ovulation cycle is disrupted. This problem normally causes infertility in women. A person who is suffering from this disorder will experience pelvic pain. The person will also develop an oily skin that is full of acne.

Vulvovaginitis

It is a vaginal infection that may be caused by various factors. It may result from failure to observe hygiene measures and guidelines. Viruses, yeast and bacteria can also lead to the development of vulvovaginitis. A person who is suffering from this condition will experience inflammations in the vaginal area. In addition, an abnormal discharge from the vagina may be witnessed. In extreme cases, bad odor and discomfort when urinating is experienced.

Prolapsed Uterus

The uterus is held in its position by special ligaments. This enables it to stay just above the vagina. A prolapsed uterus results from failure of the ligaments to hold the uterus in its position. This condition is characterized by the protrusion of the cervix in the opening of the vagina. Treatment of the disorder entails surgical operations. Once the uterus has been put in its correct position, the victim will be healed.

Conclusion

The female reproductive diseases that have been mentioned above can affect any woman. Contrary to the popular opinion that it affects certain groups of women, the truth is that all women have equal chances of developing them (Goodwin, 2010). What should be understood is that some conditions increases the chances of getting disorders. All in all, it is important to understand that all the reproductive disorders can be treated if they are diagnosed at an early stage. Always bear in mind that a health concern that is in its advanced stages is not easy to heal.

References

Goodwin, T. M. (2010). Management of common problems in obstetrics and gynecology (5th ed.). Chichester, West Sussex: Wiley-Blackwell.

Waters, S. (2008). The female reproductive system. New York: Rosen Central.

Terms in Male Reproductive System

Primary Organs are the organs that are used to produce the hormones, sperms and the eggs.

Accessory Organs are the organs involved in conveying and creating the gametes, as well as offering support for the embryo.

Urogenital System is the collective reference of both the excretory and reproductive systems of the vertebrates.

A Mesonephric/Wolffian Duct is a tube that is used to drain the kidney and also can be used as the sperm tube during copulation.

Ureter is an independent duct that is existent in birds and reptiles to drain the waste from the kidney. As such, it is exclusive of the sperm duct.

Uterine Duct/Oviduct is a duct independent of the above tubes that opens into a cloaca. A cloaca is a chamber to which all the intestinal, excretion, and reproductive tubes lead.

Testes-are a site or an organ where the sperms are produced in a male reproductive system.

Seminiferous Tubule is the tubes in which sperms grow and develop after production.

Sustentacular/Sertoli Cells are cells that basically surround the sperms in order to nourish them during growth.

Interstitial Cells are the cells responsible for the production of testosterone that is essentially male sex hormone.

Epididymis is a tube where all the seminiferous tubules lead after passing the vasa efferentia.

Urethra is a duct which is responsible for carrying both the sperms and urinary material.

Seminal Vesicles, Prostate Glands and Bulbourethral Glands are glands in a male reproductive system that produce respective secretions which ultimately make the semen in the male reproduction system.

Terms in Female Reproductive System

Oviduct is a tube also known as the uterine tube and it is used to envelope the ovary.

Follicle is a development of the oocytes contained in the female ovary. They enlarge and burst to release other secondary oocytes.

Uterus is a chamber that is also known as the womb. It is responsible for holding the embryo during its development.

Endometrium is a dense network of the blood vessels and muscular walls which supply the uterus with blood.

Vagina is a muscular tube that receive the male penis during copulation to deposit the sperms.

Cervix is a small opening where the vagina and the womb meet.

Vulva is the external genital which has a fold of a skin and exists in a female human being. It contains two skin folds including the labia majora and labia minora

Clitoris is an erectile organ of a female which is equivalent to the penis in a male.

Hymen is a membrane responsible for the reduction of the vulva in the virgin state. It reduces with time as copulation takes place.

Nervous System Terms

Central Nervous System (CNS) is a part of the nervous system that consists of two critical organs including the brain and the spinal cord.

Peripheral Nervous System (PNS) is a section of the system that consists of ganglia that are not included in the brain or spine.

Nerve net- is the most primitive form of the nervous system that has its neurons dispersed in the form of a thin layer.

Centralization is a form of nervous organization where the neurons are joined in a central integration area.

Cephalization is a situation in which the neurons exist in multiple numbers in a certain section of the body.

Nerve Cords are re-organizations of the neurons in longitudinal clusters.

Brain is expressed as the anterior increment of the CNS.