Module 4: Reproductive System Flashcards
oogenesis? explain the events in relation to meiotic development.
oogenesis the the process by which oocytes develop and mature within the ovaries.
1. oogenesis begins before birth, meiosis begins but in the first meiotic division, it arrests. it does not become a haploid cell
2. prophase - early life, primordial follicles are being stimulated to grow, the oocyte is growing larger but it is still arrested, thus it remains a diploid cell (primary oocyte).
3. from puberty, once production of hormones that can control follicle growth, the follicle starts to reach antral follicle stage to get ready to ovulate. meiosis one is completed then production of a secondary oocyte (haploid) and polar body which eventually degenerates.
4. once ovulation occurs, the second meiotic division occurs and arrests again at metaphase II.
5. meiosis is only ever completed if fertilised by sperm. if not, it just degenerates
6. if sperm does fertilise oocyte then a haploid cell is created, one ovum and a second polar body.
folliculogenesis?
process of maturation of the ovarian follicle, which contains an immature oocyte. this process involves the progression of a number of small primordial follicles into large preovulatory follicles that occurs in part during the menstrual cycle.
primordial follicle?
small, simple oocyte with one layer of cell surrounding. they sit non-growing as a pool of oocytes waiting to be stimulated (throughout the woman’s whole life) in little batches to grow into primary follicles. gradually die throughout the life of a woman, only very few that go on to ovulate.
preantral follicle?
early growing phase - early stages of development, it is characterised by the absence of an antrum which is a fluid-filled cavity adjacent to the oocyte. granulosa cells form around oocyte, with primary follicle only has one layer of granulosa cells, when it becomes multi-layered, it becomes a secondary follicle. theca cells are on the outside of the cell, basement membrane separating.
antral follicle?
early antral follicles - granulosa cells are growing and spaces in the granulosa cells are forming, fluid is starting to accumulate. theca layer is sectioned into two layers, the theca externa and the theca interna.
antral follicle - becoming larger, little spaces join and the formation of a large antrum, all fluid inside which is supporting the growth of the oocyte. the oocyte is getting large and granulosa cells are lining the antral cavity while cells round the oocyte have been differentiated into a different cell type called cumulus cells.
corpus luteum?
a hormone (progesterone, estradiol) secreting structure that develops in an ovary after an ovum has been discharged but degenerates after a few days unless pregnancy has begun.
gonadotropin?
a type of hormone produced by the anterior pituitary gland which stimulate the activity of the gonads.
LH?
Luteinizing hormone is a hormone secreted by the anterior pituitary gland and is stimulated by a gonadotropin-releasing hormone from the hypothalamus.
In females, it stimulates ovulation and helps with the hormone production needed to support pregnancy. In males, it stimulates the synthesis of androgen.
FSH?
follicle-stimulating hormone. a hormone produced by the pituitary gland in the brain which plays an important role in sexual development and reproduction.
GnRH?
Gonadotropin releasing hormone. A hormone responsible for the release of follicle-stimulating hormone (FSH) and Luteinizing hormone (LH) from the anterior pituitary
HPG?
Hypothalamic-pituitary-gonadal axis. A hormone-regulating mechanism containing three different component structures that operate in a coordinated fashion and which are involved in the regulation of several reproductive and developmental processes in humans and other species. It operates through a feedback loop involving hormones released from the gonads and the pituitary gland and the hypothalamus.
Theca cells?
A group of endocrine cells in the ovary that play an essential role in fertility by producing androgen. made up of connective tissue surrounding follicles.
Granulosa cells?
type of cell found in the ovaries, produce hormones, progesterone and estrogen. these hormones regulate menstrual cycle, follicle growth and ovulation
Androgens?
a group of sex hormones, they help start puberty and play a role in reproductive health and body development
Progesterone?
major source: ovary
stimulus for release: LH
feedback effects exerted: negative feedback on gonadotropin release by anterior pituitary and GnRH release by the hypothalamus.
effects on reproductive organs cooperates with estrogen in stimulating the growth of breasts, promoting the secretory phase of the uterine cycle and stimulates the production of cervical mucus.
metabolic effects: promotes diuresis and increases body temperature
Estrogen?
major source: ovary - developing follicles and corpus luteum
stimulus for release: FSH and LH
feedback effects exerted: both negative and positive feedback on gonadotropin release by the anterior pituitary and GnRH release by the hypothalamus
effect on reproductive organs: stimulate growth and maturation of reproductive organs and breasts at puberty and maintain their adult size and function.
infundibulum?
a funnel shaped structure that is part of the fallopian tube in the female reproductive system. it captures the newly ovulated oocyte.
ampulla?
part of the fallopian tube and is the widest section of the tube and is the primary site for fertilisation
fimbriae?
the fimbriae of the uterine tube, also known as fimbriae tubae, are small, fingerlike projections connected to the end of the fallopian tubes, through which eggs move from the ovaries to the uterus.
isthmus?
a small region which connects the ampulla and infundibulum to the uterus. egg fertilisation occurs in ampulla, then the eggs travel through the isthmus into the uterus.
seminal plasma?
fluid composed from secretions from glands in the male urogenital tract that provides a nutritious and protective medium for the spermatoza during their journey through reproductive tract
seminal fluid (semen)?
organic body fluid that contains spermatoza and is secreted by the gonads of males and can fertilise the females ovum
seminal vesicles?
a pair of convoluted tubular glands that lie behind the urinary bladder of males, they secrete a fluid that partly composes the semen.
bulbourethral glands?
two small exocrine glands in the reproductive system of males, produces a pre-ejaculate fluid called Cowper’s fluid which is secreted during sexual activity.
prostate?
a gland found in males, main function is to produce the major fluids that make up semen
corpora cavernosa?
two columns of spongy tissue in the shaft of the penis, this is responsible for an erection. The cavernosa forms most of the penis. They are filled with erectile tissue. This tissue contains nerves, blood vessels, and muscle fibers.
corpus spongiosum?
corpus spongiosum is the third tissue group that is involved in penile erection. contains the urethra, the tube through which urine and semen exit the body, and extends to form the glans penis, an expanded cap at the tip of the penis.
capacitation?
Capacitation is the process in which sperm undergo changes in the female reproductive tract that make them capable of fertilizing an egg. This process involves the removal of a glycoprotein coat, increased motility, changes in the sperm’s membrane, and preparation for the acrosomal reaction, which is essential for sperm to penetrate and fertilize the egg.
acrosome reaction?
The acrosome reaction is a crucial step in fertilization, specifically in the process of sperm-egg interaction.
- approach - aided by enzymes on its surface, a sperm cell weaves its way past cumulus cells.
- acrosome reaction - binding of the sperm to receptors in the zona pellucida causes Ca2+ levels within the sperm to rise, triggering the release of acrosomal enzymes. acrosomal enzymes form many holes in ZP.
- binding - After path cleared in ZP, 1 sperm forcibly swims towards oocyte membrane (oolemma). Sperm membrane binds to the oolemma
- fusion -
* Oocyte and sperm membranes fuse
* Only sperm nucleus and
centrioles enter oocyte
* Sperm cell membrane, tail,
mitochondria left behind - Blocks to polyspermy - oocyte membrane block and cortical reaction
zona pellucida?
The zona pellucida is a protective glycoprotein layer that surrounds the egg and plays a critical role in fertilization by serving as a barrier, aiding in sperm binding, inducing the acrosome reaction, and ensuring species-specific recognition.
cortical reaction?
The cortical reaction is a process that occurs in the egg after fertilization to prevent multiple sperm from entering. It involves the release of cortical granules, which modify the zona pellucida (the egg’s protective layer) by making it impermeable to other sperm. This reaction ensures that only one sperm can successfully fertilize the egg, preventing genetic abnormalities.