FEMALE REPRODUCTIVE SYSTEM
Author: Dr.R.Menaka
......................................................................................................................................................................................
The female genital system consists of the ovaries, oviducts, uterus, vagina and vulva.
Ovary:
The histological picture depends on the plane of section and phase of sexual cycle.
Ovary can be divided into two zones- cortex (Zona parenchymatous) and medulla (zona vasculosa).
It is surrounded by a tunica albuginea, which itself is covered by a germinal epithelium.
The functional albuginea is rich in collagenous fibers.
The cortex contain ovarian follicles, in various stages of development and regressions.
The ovarian follicle are described primay, secondary, graafian follicles.
Primary Follicles:
Each contain an oocyte surrounded by a layer of follicular cells and a basement membrane.
Secondary Follicles:
The follicular cells further proliferates and surrounded by more number of layers.
Graafian Follicles:
Further growth of follicles is characterized by proliferation of follicular cells, which form a stratified layer around the ovum.
The irregular spaces appear in the follicular mass which fuse to form a crescent shaped cavity known as antrum folliculi.
The cavity contains a fluid called the liquor folliculi. These folliculi with the formation of cavity are called graafian follicles. The stroma cells surrounding the follicles form a sheath - the theca folliculi.
Gem Hill or Cumulus Oophorus:
In a mature follicle, the ovum is pressed to one side where it is surrounded by an accumulation of follicular cells, it forms a definite projection into the cavity, known as the germ hill or discuss proligerus or cumulus oophorus.
Ovum:
The ovum with the nucleus (germinal vesicle) and nucleolus (germinal spot) is surrounded by a thick homogenous membrane the zona pellucida.
Surrounding these are tall columnar follicular cells arranged radially forming the corona radiata.
The follicular cavity is lined by several layers of cuboidal or polyhydral follicular cells forming the membrane granulosa.
There is a homogenous basement membrane surrounding the membrane granulosa.
The theca folliculi or the follicular sheath differentiates into a theca interna containing numerous epitheloid connective tissue cells and extensively capillary network.
The theca externa consisting predominantly of fibers circularly arranged and closely packed and spindle shaped cells.
Corpus Luteum:
After rupture of the follicular cavity closes over by healing and become filled with a sero-fibrinous fluid, usually containing blood.
This develops into a temporary glandular structure known as corpus luteum.
The granulosa cells enlarge the nuclei become vesiculated and stain lightly.
The cytoplasm shows progressively greater accumulation of lipid droplets and yellowish pigment granules. These are known as granulosa-lutein cells.
The epitheloid cells of theca interna also proliferate and show fatty droplets in the cytoplasm and form the theca lutein cells.
Note: If the ovum is fertilized and pregnancy occurs, the corpus luteum increases in size and becomes corpus luteum of pregnancy.
After termination of pregnancy it undergoes slow involution becoming transformed it to corpus albicans.
Atretic Follicles:
Only a few of the oocyes in the follicles reach maturity.
Most of the oocytes together with their follicles undergo atresia.
This may set in at any stage of development.
The process involves degeneration of oocyte and invasion of follicle by theca interna cells.
Medulla:
There is a network of fibro-elastic tissue with numerous blood vessels and nerve fibers.
Species differences:
Mare:
No division of the ovary into the cortex and medulla.
Ovulatory fossa located at the free border, which is covered by germinal epithelium.
Cow and Bitch:
Giant follicles- may contain 2 to 6 oocytes.
Oviduct or Fallopian Tube:
Tunica Mucosa:
The mucosa forms large primary and small secondary folds.
Epithelium- simple columnar cells. Some of which are ciliated. In ruminants- partly pseudo stratified ciliated columnar epithelium.
Tunica Muscularis: Consists of circularly arranged smooth muscle fiber.
Tunica Serosa- typical form of loose connective tissue and mesothelium.
Note:
The epithelium also shows changes during the stages of estrus cycle.
The epithelium becomes taller with greater secretory activity just before and during the estrus period.
Uterus:
Tunica Mucosa:
Epithelium- endometrium bears a simple columnar epithelium. Sometime. ciliated.
Lamina Propria- contain uterine glands. They are simple branched tubular glands.
Tunica Muscularis or Myometrium:
Three layers of plain muscle
i. An inner logitudinal
ii. A middle circular
iii. A thin outer layer
Tunica Serosa: is continuous with the broad ligament and has the structure of mesothelium.
During Reproductive Cycle:
The uterus undergoes considerable structural changes during the various satges of estrus cycle and during pregnancy.
Estrus Cycle- congestion,edema, proliferation of glandular epithelium etc.
Pregnancy- formation of placentomes, Myometrium- hypertrophied, muscle diameter increases, hyperplasia etc.
Species difference:
Ruminanats and sow - endometrium - stratified.
Vagina:
Tunica Mucosa- thrown into folds and non glandular.
Epithelium- stratified squamous epithelium.
Lamina Propria- loose connective tissue, lymphocytes, lymph nodules, elastic fibers present.
Tunica Muscularis- very typical.
Tunica Fibrosa- with dense connective tissue.
Note:
The vagina undergoes structural changes during the various stages of estrous cycle.
The changes are s follows:
1. Mucosa increases its thickness
2. Epithelium- cornified (varying degree) followed by desquamated at met estrus.
Mammary Gland (Apocrine Gland)
The mammary gland of a lactating animal is a compound tubulo-alveolar gland.
Fibro-elastic capsule surrounded
The mammary gland divided in to several lobes and lobules.
The demarcation is observed by the presence of interlobular connective tissue.
The amount of interlobular connective tissue varies considerably with the functional state of the glands being greatly reduced in a lactating gland.
The parenchyma including the secretory tubules with alveoli or acini.
The alveoli is lined by short or low columnar or cuboidal epithelium which rest on a basement membrane.
Alveoli exhibits- in different phases based on their status/ activity.
Non-Functional Status:
Gland shows abundant interstitial connective tissue.
Paranchyma shows only ducts and few alveoli.
Lactiferous ducts:
The smallest ducts are lined by secretory epithelium (cuboidal)
The larger ducts are lined by two-layered columnar epithelium.
Towards the termination there is startified squamous epithelium present.