FUNCTIONAL ANATOMY OF FEMALE REPRODUCTION

FUNCTIONAL ANATOMY OF FEMALE REPRODUCTION

Outline and histological structure of female reproductive system in human; Ovary: folliculogenesis, ovulation, corpus luteum formation and regression; Steroidogenesis and secretion of ovarian hormones; Reproductive cycles in human and their regulation, changes in the female tract; Ovum transport in the fallopian tubes; Sperm transport in the female tract, fertilization; Hormonal control of implantation; pregnancy diagnosis Hormonal regulation of gestation, Mechanism of parturition and its hormonal regulation; Lactation and its regulation.

1. OUTLINE AND HISTOLOGICAL STRUCTURE OF FEMALE REPRODUCTIVE SYSTEM IN HUMAN.

Following parts constitute the female reproductive system, a pair of ovaries, fallopian tube, uterus, cervix, vagina and accessory genital glands and a pair of mammary glands.

1. Pair of Ovaries

Each ovary is of the shape of unshelled almond and the size is 3.5 cm long, 2 cm wide and 1 cm thick. It is placed in the abdominal cavity. Ovary is attached to the uterus by ovarian ligament. Ovary is suspended from the abdominal wall by a mesentery called mesovarium. Each ovary is lined by cuboidal germinal epithelium and is solid. Underneath the germinal epithelium lies a layer of connective tissue called tunica albuginea. Underlying this layer is stroma. Stroma is further divided into dense outer cortex and less dense inner medulla. Many Graafian follicles/ovarian follicles are present in the cortex and show different stages of development. Initial stage of development is primary oocyte. As the primary oocyte develops it changes to secondary oocyte. Secondary oocyte is released from the ovary by the rupturing of ovarian wall. This process is known as ovulation.

There are around four lakhs follicles in both the ovaries of an adult woman. Most of the follicles disappear by phagocytosis during reproductive years. This process is called follicular atresia. Due to this a female produces only around 450 ova in her entire reproductive life which ends between 40 and 50 years of age.

Secondary oocyte surrounded by layers of follicular cells (discus poligerous or cumulus oopharous) is called as Graafian follicle. It is suspended in the antrum which is filled with semi-viscous fluid called liquor folliculi, secreted by follicular cells and is held by a stalk of follicular cells called germ hill. This stalk arises from membrana granulose which is multicellular layer. The outer most layer is called theca externa and the inner layer is called theca interna. Follicular cells act as endocrine cells and secrete hormone estrogen in blood. Cortex of ovary also consists of conical, yellowish cells known as corpus luteum which on degeneration is called as corpus albicans. Corpus luteum also functions as endocrine cells and secretes progesterone, estradiol and relaxin.

b. Fallopian Tube or Oviduct

Fallopian tube is around 10 cm long, muscular, tubular and ciliated structure. It lies in pelvic region, just above the urinary bladder. It is composed of outer serosa, middle muscularis and inner mucosa. Mucosa is made of simple ciliated columnar cells and secretory cells. A viscous liquid is secreted by secretory cells, which provides protection and nourishment to the ovum. Ciliated cells help in the movement of ovum. Each fallopian tube is divided into infundibulum, ampulla, isthmus and uterine part.

i. Infundibulum

This is a broad, funnel shaped proximal part. Finger like projections arise from this proximal part and are called as fimbriae. Infundibulum opens into the body cavity by an aperture called as ostium. Ostium lies near the ovary and receives egg from the ovary with the help of fimbriae.

ii. Ampulla

It comprises of the major portion of fallopian tube. It is long, thin walled and wide.

iii. Isthmus

It is a short, thick walled, ciliated and narrow straight path.

iv. Uterine Part

It is narrow and inner part which opens in the upper part of uterus.

c. Uterus

It is hollow, muscular, vascular and large (8 cm x 5 cm x 2 cm) pear shaped Structure which is present in the pelvic region above the bladder. It can be divided into three parts – fundus, body and cervix.

Fundus is upper, dome shaped part above the opening of fallopian tube. The middle and major part of uterus is the body. It has three layers – outer peritoneal perimetrium, middle muscular myometrium and highly vascular endometrium. The lower narrow part which opens in the body of the uterus by internal os and in vagina by external os is called cervix.

Uterus is the site of foetal placentation, its growth and parturition.

d. Vagina

This is a tubular structure, 10-12 cm long and extends from cervix to the outside of body. It receives the sperms during copulation, is passage for menstrual flow and forms the birth canal during labour. Hymen is the membranous structure which covers the opening of vagina – the vaginal orifice. Vagina is lined by non-keratinised stratified squamous epithelium. Glands are absent in vaginal wall.

e. Vulva

This is the external genitalia of females. It consists of the vestibule or urino-genital sinus which is in the form of depression and is in the front of anus. It has two apertures, upper external urethral orifice and lower vaginal orifice.

The anterior part is fatty and covered with pubic hair. This portion is called as Mons pubis. Corresponding to the male penis, clitoris is present in the females which are made of erectile tissue. Two large, thick- walled fold of skin form the boundary of vulva. These are labia major and contain sebaceous glands. Between labia major two small folds are present and are called as labia minora. Labia minora fuse posteriorly to form fourchette.

On either side of vaginal orifice there is a pair of Bartholin’s gland. This gland secretes a clear, viscous fluid which works as lubricating agent during copulation. The area below fourchette and anus is perineum.