Male And Female Reproductive Systems Flashcards
What is the anatomy of the male reproductive tract?
Lies outside the peritoneal cavity
Testes: produce sperm. Suspended in a forum to keep temperature 2/3 degrees lower than body.
Epididymis: sits round the testes. Stores and matures sperm. Breaks it down if not ejaculated
Vas deferens: transports sperm to vesicles (vasectomy)
Prostate and seminal vesicles: secrete seminal fluid to support sperm
Penis: made up of three muscles (2 corpora cavernosa, 1 corpora spongiosum). Erection is due to parasympathetic, ejaculation sympathetic (point and shoot)
Bulbo urethral glands: just below prostate: secrete sugar rich mucus into urethra for lubrication and contribute to pre ejaculate
What is in the seminal fluid?
Secreted by the prostate and seminal vesicles
Fructose
Citric acid
Bicarbonate (neutralises vaginal acidity)
Fibrinogen (thickener)
Fibrinolytic enzymes
What is the spermatic cord?
Suspends the testes
Formed at the deep inguonal ring
Contains: testicular artery, pampiniform plexus (veins), autonomic nerves, lymph vessels, vas deferens
What is the anatomy of a testes?
Each is surrounded by three layers of connective tissue: tunica vasculosa (blood vessels), tunica albuginea (thick layer that formed the lobes of the testes), tunica vaginalis (covers testes and epididymis)
Each one has around 300 lobules, each separated by a septa. Each lunula contains coiled seminiferous tubules. These drain into the epididymis, which drains into the vas deferens
Arterial blood supply: testicular arteries from the aorta via the spermatic cord
Lymphatic drainage: para aortic lymph nodes
What is the anatomy of the female reproductive tract?
Ovaries (inside peritoneal cavity)
Fallopian tubes joined to ovaries by fimbrae. They are lined with cilia and spiral muscle to waft egg towards uterus
Fertilisation usually occurs in the widest section - ampulla
Uterus - supported by tone of pelvic floor and ligaments. Made up of three layers (endometrium, myometrium, perimetrium) endo is shed at menses due to vasoconstriction of arterioles which causes ischaemia
Cervix at bottom. 1cm either side of cervix is ureter. Important when considering cervical cancer
All sterile above the cervix did to frequent shedding of the endometrium and thick cervical mucus
How does the number of germ cells in the gonads differ across lifespan?
About 6 million present at birth
Game to genesis begins at puberty
Speratogonia undergo differentiation and self renewal
Pool available for subsequent spermatogenic cycles throughout life (continuous fertility)
Produce ~1500 mature sperm a second
How does the number of germ cells in ovaries differ across lifespan?
Before birth, multiplication of oogonia to ~6 million per ovary
Form primary oocytes within ovarian follicles (primordial follicle)
These begin meiosis and are halted in prophase
Some primordial follicles degenerate (atresia)
At birth around 2 million per ovary remain
By puberty less than 0.5 million per ovary remain due to further atresia
How does male gametogenesis occur (spermatogenesis)?
Speratogonium (2n 44XY) —> mitosis —>
Primary spermocytes (2n 44XY) —> 1st meiosis —>
Secondary spermocytes (n 22X/Y) —> 2nd meiosis —>
Spermatids (n 22X/Y) —> differentiation —>
Spermatozoa (n 22X/Y)
What is the anatomy of the seminiferous tubules of the testes?
Each seminiferous tubules is surrounded by tunica propria (flattened cells several cells thick to form a basement membrane)
Most cells that lie against the basement membrane are spermatogonia
These then mature and move inwards forming primary and secondary spermocytes and ultimately spermatids that are released into the duct.
There are also Sertoli cells which lie inside the tubules and support spermatogenesis and secrete hormones
Leydig cells lie outside the tubules and secrete hormones
What hormones are produced by the Sertoli cells of the testes?
These have FSH receptors
Function: support developing germ cells, assisting movement from tunica propria to lumen, transfer nutrients from capillaries to germ cells, phagocytosis of damaged germ cells
Hormones: inhibin and activin (negative and positive feedback on FSH).
Anti mullerian hormone (this stops formation of Fallopian tubes which obvs men don’t need)
Androgen binding protein (directs testosterone from leydig cells to germ cells)
What hormones are produced by the leydig cells of the testes?
These have LH receptors
Hormones: androgens (testosterone, androstenedione, sehydroepiandrosterone (DHEA))
These can be aromatised to oestrogens
How does female gametogenesis occur (oogenesis)?
Oogonium (2n 44XX) —> mitosis —>
Primary oocytes ( 2n 44XX) —> 1st meiosis —>
Secondary oocytes (n 22X) and a polar body —> 2nd meiosis —>
Ootids (n 22X) and a second polar body —> differentiation —>
Ova (n 22X)
HOWEVER
In the 2nd trimester of pregnancy all oogonia in the foetus develop into primary oocytes (primordial follicles) their progression is then halted
At menarche a few primordial follicles develop into secondary oocytes and are released. If a secondary oocyte and sperm fuse this will cause an influx of calcium stimulating the second meiotic division to form the ova
How does follicle development (folliculogenesis) in the ovaries occur?
- Primordial follicle (primary oocyte) present at birth
- Primary follicle - primary oocyte still but with layers of granulosa cells and the a cells
- Secondary follicle - fluid filled cavity (antrum) develops. LH and FSH receptors
- Mature/graafian follicle - forms due to LH surge. Secondary oocyte forms
- Ruptures surface of ovary
- Corpus luteum - released progesterone and oestrogen for the first 40 days of pregnancy of it occurs
Progression from step 2 to 3 only happens during the menstrual cycle
What hormones do the theca cells of the ovary produce?
These are a later on the outside of the follicles
They support folliculogenesis - structural and nutritional support of growing follicle
They are stimulated by LH to produce androgens (these can then be made into oestrogens using the granulosa cells)
What hormones do the granulosa cells of the overuse produce?
Inner part of the follicle
FSH stimulates the granulosa cells to convert androgens into oestrogens by aromatase
They also secrete inhibin and activin (effects on FSH)
AFTEr OVULATION
Turn into granulosa lutein cells that produce protesterone (has a negative feedback effect on the hypothalamus and ant pituitary so maintains production of pregnancy hormones)
Also relaxin which helps endometrium prepare for pregnancy
