Anatomy of the female reproductive sytems PDF

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Summary

Structure and function- Anatomy of the female reproductive system Functions of the reproductive systems - Not essential to the life of the individual but essential to species survival - Produce haploid gametes (gametogenesis) - Store, nourish and transport haploid gametes for fertilisation - Interna...

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25.02.20 Structure and function- Anatomy of the female reproductive system Functions of the reproductive systems - Not essential to the life of the individual but essential to species survival - Produce haploid gametes (gametogenesis) - Store, nourish and transport haploid gametes for fertilisation - Internal or external - Internal: oviparous (egg), viviparous(embryo develops within body and give birth to live young) , ovoviviparous (variation between two, egg is present inside the body and the embryo develops with in egg and young given birth to like viviparous no placental connection) Sex determination - Gonadal sex is determined by the sex chromosomes in mammals and birds XY for females and XX for females - Genitalia determined by hormones - Androgen release in Usero causes masculinisation of genitalia in mammals -

Therefore possible for humans with female gonadal sex, but male external genitalia as a result of exposure to high levels of testosterone in utero. Oestrogen release in o o causes feminisation of genitalia in birds Not genetically determined animals: tortoises depend on heat, worms are hermaphrodites

Female genitalia - Internal and external Internal - Shares the pelvic cavity with the bladder and sigmoid colon - Covered superiorly by peritoneum - Follows the curve of the sacrum - Infra peritoneum - Provides space for potential pus or blood from infection- called the pouch of Douglass- can take needle up vagina to take sample of the fluid -

Different from male as it is open- the vagina is open

Ovaries - Maturation of the oocytes - Oogenesis happens here - Total number of oocytes at birth - Egg cell is surrounded by cells called the follicle which is important in terms of development and hormone release - Hormone production; oestrogen and progesterone

25.02.20 Oogenesis Stage 1 - Primordial follicle- pretence at birth. - several months before puberty they begin to develop. Surrounded by single layer of squamous cells called granulosa cells and basal lamina - Primary oocytes have a large nucleus with dispersed fine, granular chromatin, prominent nucelolus and a little cytoplasm. - The primary oocytes that have formed are diploid, but gametes need to be haploid cells. Therefore there is a requirement to undergo meiotic division, which starts during foetal development but is then arrested during prophase of meiosis 1. The primary oocytes which survive are the cells that become encapsulated by flat, spindle-shaped follicular (preganulosa) cells and become enclosed by a basement lamina. These structures are the primordial follicles, which are approx 30 to 60um in diameter. The first primordial follicle usually appears about 16 weeks intrauterine and the final one is formed approximately 6 months after birth. - The primordial follicles are embedded in the cellular cortical stroma. Many (probably at least 90%) of these primordial follicles will never progress beyond this stage. -

There is no further development until puberty.

Stage 2 - Primary follicle undergoes further change to be multilayered - The granulosa cells increase in number abd thickness forms stratified. Increase number of oestrogen being produced because there’s more of them - Zona pelluicida is assembled - Once puberty is reached there is stimulation of 20 to 40 primordial follicles each month by follicle stimulating (FSH) and lutenising (LH) hormones to continue maturation. This starts with recruitment of the cells in the luteal phase and the growth in the follicular phase of the menstrual cycle. However only one of these cells will mature with the rest dying. - The secondary follicle is formed as the proliferation of the granulosa cells occurs to give several layers and ovarian stromal cells differentiate to form theca cells. The inner layer is the theca interna. The cells of the theca interna increase in size and develop features characteristic of steroid hormone producing cells and they begin to produce oestrogen. The outer layer cells of the theca externa remains small and compact. A capillary network develops to supply the follicular unit. As the granulosa cells secrete fluid into the centre of the follicle, small fluid filled spaces develop, which fuse to form one larger cavity (the antrum) containing follicular fluid. - The oocyte has now reached almost its full size and as can be seen is off centre. Primary follicles are produced (unilayrered) - Granulosa cells increase in size and change from flat to cuboidal - The oocyte produces zona pellucida which is made of glycoproteins an is important to binding of spermatozoa Stage 3 - Secondary follicle produced - Spaces develop containing follicular fluid- coalesce to form a cavity - Production of oestrogen by granulosa cells

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The secondary follicle is formed as the proliferation of the granulosa cells occurs to give several layers and ovarian stromal cells differentiate to form theca cells. The inner layer is the theca interna. The cells of the theca interna increase in size and develop features characteristic of steroid hormone producing cells and they begin to produce oestrogen. The outer layer cells of the theca externa remains small and compact. A capillary network develops to supply the follicular unit. As the granulosa cells secrete fluid into the centre of the follicle, small fluid filled spaces develop, which fuse to form one larger cavity (the antrum) containing follicular fluid. The oocyte has now reached almost its full size and as can be seen is off centre.

Stage 4 -

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Graafian follicle (tertiary) Antrum-large fluid filled cavity Surrounded by corona radiata- provide nutrients The follicle has developed into a mature Gaafian (teritary) follicle The fluid-filled cavity enlarges becoming known as the antrum, the fluid is slightly viscous and rich in hyaluronic acid. The antrum almost totally encircles the oocyte at the centre of the follicle but a small gap is left, called the cumulus oophorus, which attaches the oocyte to the rest of the follicle. These changes produce a follicle known as the Graafian follicle. Follicle maturation takes approx 15 days and the meiosis I can now be completed.

Ovulation -

The stimulus for ovulation is luteinising hormone, which causes the follicular wall to become thinner and weaker and so ruptures to release the ovum. At ovulation the mature graafian follicle is so large there is a bulge in the ovary surface and locally breaks down the wall, assisted by proteolytic enzymes, and the ovum moves out of the ovary and into the fallopian tube. This is aided by the action of fimbrae drawing it into the infundibular opening of the oviduct. The ovum is then transported by means of ciliary movement and muscular contraction to the ampulla. Where fertilisation may take place.

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Proteolytic activity stimulated by gonadotropin Ovum expelled into entrance of the uterine tube Released into entrance does not have to go directly into tube and it can end up in the peritoneum cavity

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Corpus luteum - Yellow body (fatty) - Endocrine function follicular cells release progesterone - Involution- breaks down if not fertilised, stops producing progesterone and produces collagen forming the corpus albicans - Corpus albicans is the white body - Cells replaced by collagen - Scar

25.02.20 Once the Graafian follicle loses its oocyte it becomes transformed to corpus haemorrhagicum or corpus luteum of menstruation. The clot filled lumen undergoes progressive organisation and fibrosis over following weeks, functioning briefly as an endocrine organ. LH causes: (1) the granulosa cells to enlarge and become secretory cells producing progesterone. The progesterone causes changes to uterus wall in preparation for potential fertilisation. They also have an increased amount of lipid in the cells. (2) the theca interna cells to increase in size and to continue to secrete oestrogen, though some of these cells just become small cells. The basement membrane between the zona granulosa and theca interna breaks down and these layers are invaded by blood vessels to form vascular network. The result is a Corpus luteum that has a central area of fibrosing blood clot, surrounded by broad zone of lipid rich cells known as lutein cells. It reaches its maximum size approx day 20 of menstrual cycle, when approx 2cm long and 1.5cm wide. The corpus luteum can only be maintained by continuous stimulation by LH. Therefore after 12-14 days it begins to regress to form a functionless corpus albicans. The corpus albicans may persist in the ovary, as with age more and more corpus albicans are seen in the ovary. There is a dispute about whether the corpus albicans shrink and remain or entirely disappear. The involution of the corpus luteum to form the corpus albicans begins with a decrease in size of the granulosa and theca lutein cells and they become vacuolated. Their production of oestrogen and progesterone decreases. There is stimulation of the theca externa cells to produce collagen which replaces the cells. The end result is the corpus albicans which is small ovoid collagenous/fibrous tissue structure. The corpus albicans may persist in the ovary as with age the ovary appears increasing full of them. There is a dispute as to whether the coprus albican shrink remaining as tiny structures or entirely disappear. The question is – are there sufficient corpus albicans present for the number, which must have been formed throughout the reproductive years.

Uterine tube - Picked up by the infundibulum - To increase pick up of cell fimbriae waft and vibrate creating a current - Muscular tube – which helps as peristalsis happens to move cells and to move spermatazoa in opposite direction - Site of fertilisation - Ampulla- most likely place for fertilisation - Intramural- within wall of uterus Epithelium of the uterine tubes - Secretory cells- watery secreation for gamete nourishment - Ciliated- cillia beat increases in response to high levels of oestrogen- help move oocytes down tube - Cells are vulnerable to bacteria- chlamydia(can reduce fertility and increase likelihood of fertilised cells to take place in tube= ectopic pregnancy) -

The distal part of the tube (ampulla and isthmus) lined with highly convoluted mucosal folds which project into the lumen of the tube. Fewer folds in the isthmus.

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The ciliated cells predominate near the ovary end which may be to ensure the ova moves up the tube and sperm in the opposite direction. Though the peristaltic movement of the muscle layers may be more effective at moving the ova and sperm than the cilia.

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The size of the cilia varies throughout the menstrual cycle with the maximum height being reached at ovulation. Growth of the cilia is related to oestrogen and shrinkage to progesterone.

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The secretions are from the non-ciliated cells that have microvilli on their apical surface and are assumed to have a nutritive role to feed sperm and ova before and after fertilisation.

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It is these cells lining the epithelium of the uterine tube which can be affected by Chlamydia and other microorganisms. Cilia are lost therefore reducing the ability of the oocyte/zygote being passed through the tube effectively.

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The ciliated cells predominate near the ovary end which may be to ensure the ova moves up the tube and sperm in the opposite direction. Though the peristaltic movement of the muscle layers may be more effective at moving the ova and sperm than the cilia.

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The size of the cilia varies throughout the menstrual cycle with the maximum height being reached at ovulation. Growth of the cilia is related to oestrogen and shrinkage to progesterone.

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The secretions are from the non-ciliated cells that have microvilli on their apical surface and are assumed to have a nutritive role to feed sperm and ova before and after fertilisation.

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De-ciliation, rupure and damage to cell junctions.

Ectopic pregnancy - fatal for baby and can be for mother - Can also be fertilised outside of tube and can imbed In abdominal cavity and begin to develop

Uterus -

Divided into 2 principle components - the body and the cervix. Separated at the isthmus (narrowing) of the uterus

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Superior 2/3rds of the organ form the body

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rd Inferior 1/3 = cervix (neck) 2 parts uterine and vaginal parts

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Body had a fundus (base) = rounded part superior to the openings of the uterine tubes.

Humans can also look like these counterparts

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Broad ligament - Broad ligament- double fold of the peritoneum - Not ligaments in the musculoskeletal sense - Layers of the peritoneum as in those that cover the digestive tract Uterine wall The uterus can be divided into 3 regions the fungus and the body which have the same histological structure and the cervix which if histologically different - Myometrium interwoven smooth muscle/CT- provide the power fro expulsion of the foetus during childbirth Hormonal response Hypertrophy/hyperplasia adapt to the growing foetus - Endometrium Epithelial layer Mensural cycle- zygote embeds itself Mucous lining changes with the menstrual cycle, partly shred during mensuration and embryo becomes embedded within it - Para/perimetrium (same as the visceral peritoneum but is the histological name

External genitalia -

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Vestibule = porch Vagina and urethra opens into the vestibule Bordered by the labia minora = hairless folds of skin Located most anterior = clitoris = dense sensory innervation – equivalent/vestigial to the glands of the penis – covered by the hood or prepuce Protected by the fatty pubis anteriorly and the labia majora = large fatty folds with pubic hair...