W1L2Tu Female reproduction: anatomy and hormone Flashcards
The female human reproductive tract
Female reproductive tract: Ovaries
produce oocytes + hormones (oestradiol + progesterone)
§ Follicle:fluid filled structure containing an egg, produces oestrogen to support egg, forms corpus luteum once egg ovulated
§Corpusluteum: produces progesterone which locally enters uterine environment to prepare endometrium if embryo implants
Ø No fertilisation = no signal from embryo = CL reabsorbed into ovary = no progesterone support = endometrium shed
§ Coelomic epithelium surface (over tunica albuginea) degrades to expel oocyte
§ Cortex: consists of ovarian germ cell follicles + stroma
§Medulla: fibrous connective tissue stroma, blood veses, nerves
Female reproductive tract: Oviduct
Oviduct/Fallopian tube: convoluted tube, muscular wall (move egg), secretory epithelium
- Egg + sperm transport, fertilisation site
Female reproductive tract: Uterus
Consist of 3 layer
§ Myometrium: 2 layers of muscle – circular + longitudinal
§Endometrium: secretory glands in stroma,where embryo implants
§ Luminal epithelium: columnar epithelium, secretory (secretes proteins into lumen)
Female reproductive tract: Cervix
tough connective tissue stroma, epithelium secretes mucus
§Closes uterus from vagina :prevents bacteria/ sperm from vagina entering uterus+retains embryo during pregnancy
Female reproductive tract : vagina
muscular wall, squamous epithelium (keratinised), sensitive to oestrogens, role in coitus
Female reproductive tract: external genatilia (labia & clitoris)
Labia:highly variable in morphology
§ Clitoris: erectile tissue, same embryological origin as penis
Species variation of the female reproductive tract
§ Human: uterine horns (shorter due to 1-2 offspring at a time), uterus (bigger to house baby for longer)
§ Cow: oviduct (highly coiled near ovary, long 25cm), uterine horns (very long, potential for twins, large calf 25kg), uterus (relatively small), cervix
(superior vagina surrounds inferior cervix laterally/posteriorly)
§ Rat: ovary (lots of fat), oviduct (coiled near ovary), uterine horns (very long, room for litter of embryos to implant), uterine body (very small)
§ Tamar wallaby: 2 independent uteri (gravid + non-gravid) each with its own cervix, anterior vagina connects to median vagina (where joey travels), lateral vagina stores sperm from multiple males, ureters travel b/w median + lateral vaginas to bladder (prevents fusion into 1 uterus), copulatory plug after mating event
Other variation within female tract
Ovaries: mono-ovular (releases1egg) or polyovular
§Foetal development: paired Mullerian ducts fuse to various extents
Ø Humans: extensive amount of fusion = large uterine body + small uterine horns
Ø Rats/pigs: little fusion = large uterine horns
§ Vascular supply to ovary +uterus varies with reproduction status (nutrients,hormones)
§Same main hormones across species (oestrogens, progestogens, gonadotrophins, prostaglandins)
Ø Differences in timing/location of expression b/w species
Primordial and Primary follicles
-At birth fixed number of follicles that decrease over lifetime- until menopause (human)
-Primordial follicles are the earliest stage of oogenesis. Oocyte plus one flat layer of cells.
-Oogonium approx 20 μm diameter, arrested in meiotic prophase, then grow and become a primary follicle.
-Primary follicle have-Zona pellucida (acellular layer) present, a glycoprotein layer that surrrounds oocyte and separate it from granulosa layer. Single squamous or cuboidal layer of granulosa cells surrounded by membrana propria (basement membrane)
-Prmary follicle are Godonatrophin independent
-Regulation of development onset unclear
Secondary/ Prenatal follicle
§ Gonadotrophin (FSH/LH) dependent (receptors develop)
§ Lipid droplets accumulate + mitochondrial biogenesis begins
§ Granulosa cells form stratified layers
§ Theca cells recruited by oocyte signals + surround follicle
Secondary - Early Antral follicles
Theca differentiates into theca externa + interna (interna vascularised)
§ Granulosa layer (avascular) proliferates +clefts appear b/w cells+ fluid accumulates =antral stage
Tertiary Follicle (Antral)
Oocyte surrounded by specialised granulosa cells
Ø Cumulus cells: surround oocyte, communication + provide nutrients to oocyte
Ø Mural granulosa cells: oestrogen production, inhibin secretion
-Central cavity antrum contain follicular fluid
§ Basement membrane (membranapropria) separates granulosa+theca cells
§ ReceptorsforLH (theca cells)+FSH(granulosa cells)
-Blood vessels only in theca cell
-Oestrogen and Inhibin secretion
Atresia
Fate of most antral follicles
Group or “cohort” of follicles grow but only one becomes dominant and ovulates.
Granulosa and theca layers break down
Hormone production stops
Oocyte degenerates
Follicle remnants resorbed
Follicle forms Corpus Luteum after ovulation
Corpus Luteum (CL)
Granulosa cells transform and proliferate
Theca cells transform, migrate into core, and mingle with granulosa derived cells
Production of progesterone leading to Massive vascularisation and angiogenesis (tumour-like growth)
Corpus Albicans
-Regressing CL
-No progesterone
