Female Reproductive System of mammals

Female Reproductive System of mammals

The female reproductive system consists of bilateral:1. Ovaries and uterine tubes (oviduct)2. Bicornuate uterus, 3. Cervix,4. Vagina, 5. Vestibule, 6. Vulva and

associated Bartholin,s gland which secrete mucus.

Function: Concerned with the (a) Production and transport of ova,

(b) Transport of spermatozoa, (c) Fertilization, (d) Accommodation of conceptus until birth (e) Hormone

Production.

Avian Reproductive System (Oviduct) Two oviducts at birth, however, the left one become functional at maturity. Different parts are: 1. Ovary, 2. Infundibulum, 3. Magnum4. Isthmus, 5. Uterus, 6. Vagina, 7. Cloaca.Function: Ovary: Production of ova. Infundibulum: Picking of Ova and transport it to the magnum. Magnum: Secretion of albuminIsthmus: Form shell membrane Uterus: Form hard shellVagina: Expelled mature eggs to exterior Cloaca: common opening for digestive, urinary and reproductive tract.

Histology of Ovary The ovary is a combined exocrine and endocrine gland, it produces both ova (exocrine function) and estrogen and progesterone hormone (endocrine function).

The structure of the ovary varies with the species of animals, age, and sexual cycle. In general it is ovoid in shape and surrounded by connective tissue layer known as tunica albuginea.

The ovary is divided into outer cortex and inner medulla. The cortex is a broad peripheral zone containing follicles, corpora lutea, and interstitial endocrine cells (bitch). whereas, medulla contains connective tissue, blood vessels and lymph vessels and “Retia Ovarii”.

Retia Ovarii

Retia Ovarii are network of irregular channels lined by cuboidal epithelium and located in the medulla of the ovary of ruminants and carnivors.•Function: The retia ovarii may differentiate into follicular cells when in juxtaposition (opposite position) to the oocyte.

Follicles of the Ovary (in the cortex)• When immature or mature ooctyes surrounded by

single/many layers of ovarian cells then the structure designated as “follicles”. Follicles are located in the cortex of the ovary. The follicles may be:

1. Primordial follicles.2. Primary follicles.3. Secondary follicles4. Tertiary follicles or graafian follicles5. Atretic folliclesOther structure of the cortex includes:Corpus albicans, corpus luteum, Intertitial

endocrine cells, blood vessels, lymph vessels and connective tissue cells.

Primordial, Primary, and Atretic Follicles

Primordial Follicles:These follicles are composed of primary oocyte surrounded by simple squamous epithelium. Primordial follicles arise prenatally by mitotic proliferation of internal epithelial cell masses of the ovarian cortex. Primordial follicles are evenly distributed in the ruminant and sow; in the form of clusters in carnivors.

Primary Follicles:Primary follicles are composed of primary oocyte

PrimordialFollicles

PrimaryFollicles

Atretic follicles

surrounded by a simple cuboidal or simple columnar epithelium. The primary oocytes begins its first meiotic division before birth, but the completion of prophase does not occur until the time of ovulation. Millions of potential oocytes present at birth in a single ovary. Most of them regress and only few hundred ovulate during a normal lifetime. Atretic Follicles: Because of few percentage of oocytes ovulate most of the oocytes of the ovary undergo degeneration and glassy appearance. This structure is called atretic follicles. In primordial and primary follicles oocyte first undergo degeneration, in advance stages reverse.

Secondary Follicles • The secondary follicles composed of a primary oocyte

surrounded by many layer of follicular cells known as granulosa cells. These granulosa cells cells originates from the proliferation of the follicular cells of the primary follicles.

• The secondary follicles are also marked by a glycoprotein layer (zona pellucida) around the oocytes. These zona pellucida is secreted by the oocyte itself or by the granulosa cells itself.

• As development proceeds , small fluid cleft (future antrum) is formed with the granulosa cells, and a layer of spindle shaped cells, the theca cells formed around the granulosa cells.

• In sow and bitch ovary a secondary follicle may contain many oocytes, known as polyovular follicles.

Tertiary Follicles/Mature Follicles/Graafian Follicles Mature follicles composed of primary oocyte or secondary oocyte (oocyte immediately before ovulation) surrounded by many layer of follicular cells. Following layer of cells are observed from the oocyte:1. Corona radiata: immediately around the zona

pullucida.2. Cumulus oophorus: 2nd layer of cells.3. Stratum granulosum: Just after the cumulus

cells. Granulosa cells secrete fluid of the antrum.

4. Theca interna: Spindle-shaped cells around the granulosa cells.

5. Theca externa: The outer most cell layer of loose connective tissue with fibroblast arranged concentrically around the theca interna.

Antrum

Ovulation

Stigma

Ovary of cow

Release of mature oocyte from the ovary to the fallopian tube by chemical, mechanical, and hormonal means is called ovulation.

Process of ovulation: When the mature follicle fully developed it protrudes from the ovary. This condition is called stigma. Increase secretion of liquor folliculi cause swelling of the follicle. Follicular wall become thinRupture of the follicle.Release of oocytes along with corona radiata into the peritoneal cavity.

Corpus hemorrhagicum, Corpus luteum, and Corpus albicans

Corpus luteum

Corpus hemorrhagicum: During ovulation blood vessels ruptured which cause bleeding inside the follicle, and the follicle looks like red mass, hence known as corpus hemorrhagicum. Corpus luteum: The granulosa cell and theca interna cell enlarge and hypertrophied, accumulate yellow pigment (lutein). The mass now become yellow. This mass is called corpus luteum.Corpus albicans: After the regression of corpus luteum the mass is replaced by white tissue.

Size of mature follicle and corpus luteum

Size of mature follicle:Cow- 15-20mmMare- 50-70mmGoat, sow and ewe: 10mmBitch-2mmSize of corpus luteum:Corpus luteum is fully developed in cow after 9-12 days of ovulation and attains a diameter of about 25mm.

Function of Ovary

• Production of oocytes.• Secretes estrogen by granulosa cells, and

progesterone by the corpus luteum.

Uterine Tube /Oviduct/Fallopian Tube• The uterine tubes are bilateral, tortuous structures

from the region of the ovary to the uterine horns. Uterine tubes convey ova, spermatozoa and zygotes. Three segments of the uterine tube can be distinguish:

1. Infundibulum: Funnel shaped portion near the ovary.

2. Ampulla: Extending from the infundibulum to the isthmus.

3. Isthmus: Narrow part open into the uterine horn.

Image for the Section of Uterine Tube

Histology of the Uterine Tube• The epithelium is simple columnar or

pseudostratified columnar with motile cilia on the majority of the cells. The epithelia is secretory and non secretory type. The secretory cells become higher during luteal phase. Their secretion provides nutrient to the ovum and zygote.

• The mucosa is folded and continous with the submucosa. The ampula is highly folded followed by Infundibulum and isthmus. In the cow, approx. 40 primary and secondary fold. In sow and mare the tube is more folded. In the isthmus there are about 8-10 folds, no secondary folds.

Histology of the Uterine Tube• The tunica muscularis chiefly circular smooth

muscle fibers. In the infundibulum and isthmus the muscle layer is thin. It is thick in the isthmus.

• The tunica serosa consist of connective tissues and contains many blood vessels and nerves.

Histology of the Uterus

Histology of the Uterus• The uterus is the implantation site of the conceptus.• The mammalian uterus consists of three layer:1. Endometrium: The inner most layer is the endometrium.

The functional zone is a thin layer lined by simple columnar epithelium which slough off during estrus cycle. The subepithelial tissue consists of lymphocytes, monocytes, plasma cells, fibroblasts and other connective tissue cells and fiber. Melanocytes also present here in the sheep.

Next to the functional zone is the basal zone. In the endometrium there are numerous simple brached, tubular gland which is lined by psedostratofied columnar epithelium also.

Histology of the Uterus• These gland is know as uterine gland which supply

nutrient to the embryo. The height of the gland depends on the phase of estrus cycle as well as pregnancy of animals.

• In the mare endometrial cups are present in the layer.• In the ruminant thickening of the endometrium called

caruncles are present which is rich in fibroblasts and blood supply. Caruncles are the site for the attachment of fetal placenta to maternal placenta.

Histology of the Uterus

• Myometrium: Consists of thick inner circular and outer longitudinal smooth muscle fiber. Vessels are also rich here.

• Perimetrium: Consists of tunica serosa lined by connective tissue fiber with their cells and mesothelium.

Cervix of Female Reproductive System

Histology of the Cervix

Simple columnar Epithelium

Epithelium: Simple squamous epithelium. Secretory cells are also present which secrete mucus during estrus and pass through the vagina.During pregnancy it causes mucus plug.

In the sow 90% of the lining epithelium is stratified squamous epithelium.

The lamina propria is of connective tissue and Tunica muscularis consists of inner circular and outer longitudinal smooth muscles.

Histology of the Vagina of Animals

The vagina consists of :1. Lamina epithelia: Stratified squamous

epithelium in animals. In cow the cranial part is lined by simple columanar and in sow the whole length of vagina is lined by stratified polyhedral cells.

2. Lamina propria-submucosa is of connective tissue.

3. Tunica muscularis is of 3 layer of smooth muscle.

4. Tunica adventitia is of connective tissue.

Avian Oviduct

The oviduct of chicken is lined by stratified squamous epithelium in all the segment.The Infundibulum and vagina is aglandular.In the lamina propria of magnum there is an albumin producing gland (pyramidal cells), in the isthmus there is a shell membrane producing gland (Pyramidal cells), and in the uterine lamina propria hard shell producing glands (polyhedral cells)are abundant. Submucosa consists of connective tissue and Tunica muscularis consists of smooth muscles.

Oogenesis

During embryogenesis

At puberty