Repro Flashcards
Describe the different stages of follicle development during folliculogenesis.
Primordial follicles (non-growing)
Primary follicle - 1 layer of granulosa cells
Secondary follicle - > 1 layer of granulosa cells
Early antral follicles - theca interna (internal layer) & theca externa (external layer)
Antral follicles - large antrum space and fluid supporting the oocyte.
What regulates follicle growth of primordial and preantral follicles?
- Gonadotropin-Independent Regulation (e.g., FSH and LH) :
- Intraovarian factors, including growth factors like insulin-like growth factor (IGF) and paracrine factors produced by granulosa and theca cells, play significant roles in regulating follicular growth.
- Stimulatory factors that promote activation and recruitment of dormant primordial follicles and inhibitory factors that maintain quiescence and prevent apoptosis
What regulates follicle growth of antral follicles?
- Hormonal Regulation: i.e. FSH and LH
- estrogen: promoting the growth and maturation of antral follicles, as well as influencing the feedback loop that regulates FSH secretion from the pituitary gland.
- Intraovarian and Paracrine Factors
- The interaction between the developing antral follicles and the hypothalamic-pituitary-ovarian (HPO) axis is governed by feedback mechanisms.
- Anti-Müllerian Hormone (AMH)
What are the 2 major functions of ovarian follicles?
They release an egg during ovulation, and they release estrogen and progesterone, sex hormones that support implantation and other functions.
What stage is the oocyte in a primordial follicle?
The oocyte in a primordial follicle is in a prophase stage of the first meiotic division.
Ovarian Reserve - pool of oocyte, will sit in ovary during women’s life. Gradually decline over reproductive live. <1000 left = menopause
What stage is the oocyte in an antral follicle, just before ovulation? Is it fully mature?
In the antral follicle, just before ovulation, the oocyte is in a stage known as the metaphase II (MII) stage. At this point, it is considered fully mature.
What are the major cell types in an antral follicle?
Granulosa cells
Theca cells
Oocyte
Antrum
When does oogenesis begin?
Oogenesis is the process of the development and maturation of female gametes, known as ova or eggs. Oogenesis begins before a female is even born, during fetal development.
When does folliculogenesis begin?
Folliculogenesis is the process of the development of ovarian follicles in the female reproductive system. It begins before a female is born and continues throughout her reproductive years.
Describe the hypothalamic-pituitary-gonadal (HPG) axis. What hormone is produced by ‘H’? What 2 hormones are produced by ‘P’? What 2 hormones are produced by ‘G’ in females?
‘H’ refers to the hypothalamus, which produces gonadotropin-releasing hormone (GnRH).
‘P’ generally refers to the pituitary gland (specifically, the anterior pituitary). The anterior pituitary produces FSH and LH.
‘G’ refers to gonads and in females is the ovaries and produces estrogen and progesterone
What is the relationship between GnRH and FSH/LH production?
The hypothalamus produces and releases gonadotropin-releasing hormone (GnRH) in a pulsatile manner.
GnRH stimulates the anterior pituitary gland to release two key hormones: follicle-stimulating hormone (FSH) and luteinizing hormone (LH).
FSH stimulates the development of ovarian follicles in females and sperm production in males.
LH triggers ovulation in females, supports the formation and maintenance of the corpus luteum (which produces progesterone), and stimulates testosterone production in males.
Feedback mechanisms involving sex hormones (estrogen, progesterone, and testosterone) exert negative feedback on the anterior pituitary and hypothalamus.
Describe the 2-cell 2-gonadotropin hypothesis of steroid hormone production in females. What are the 2 cells involved? What are the 2 gonadotropins involved?
The 2-cell, 2-gonadotropin hypothesis describes the cooperative interaction between granulosa cells and theca cells in the ovaries, responding to the gonadotropin hormones FSH and LH from the anterior pituitary. This interaction is central to the production of estrogen, a critical hormone in female reproductive physiology.
List the 2 major ovarian hormones that regulate female reproduction. Where are they produced in the ovary? What are their primary functions in the menstrual cycle?
Estrogen: produced by granulosa cells within ovarian follicles. Primary function is to develop and mature ovarian follicles
Progesterone: produced by corpus luteum, which forms in the ovary after ovulation. Primary function is to maintain and prepare uterus lining for potential embryo implantation (pro-gestation)
Describe the hormonal profile during the menstrual cycle. When and why does ovulation occur? When and why does menstruation occur?
Menstrual Phases: Follicular phase & luteal phase, separated by ovulation.
Ovulation typically occurs in the middle of the cycle around day 14 in a 28 day cycle.
LH surge triggers the release of an oocyte
Menstruation occurs at the end of the cycle if pregnancy does not occur. The drop in progesterone levels (due to corpus luteum degeneration) causes the blood vessels in the uterine lining to constrict and the endometrium to shed.
Which hormone is dominant in the follicular phase and which
hormone is dominant in the luteal phase of the menstrual cycle?
The dominant hormone during the follicular phase is estrogen
The dominant hormone during the luteal phase is progesterone
Describe the major compartments and cells of the testis and their functions.
2 functional compartments
The intratubular compartment:
- seminiferous tubules
- lined with complex stratified
germinal epithelium
- contains sperm cells and sertoli cells
- Main function is Sperm production
The peritubular:
- neuronal and vascular elements
- connective tissue, immune cells,
interstitial Leydig cells
- Main function is Steroid (androgen) production
Describe the different stages of sperm production (spermatogenesis) and understand the role of
spermiogenesis.
Spermatogenesis is the production and maturation of sperm
- Mitotis
- produces large numbers of cells - Meiosis
- generates genetic diversity and ½
chromosomes - Spermiogenesis (Cytodifferentation)
- packages the chromosomes for effective
delivery to the oocyte
Describe the feedback loops that regulate testosterone (T) production.
Increasing levels of testosterone act on the hypothalamus and pituitary through a negative feedback loop to inhibit the release of GnRH and FSH/LH, respectively. This results in a decrease in testosterone production in the testes.
Describe the levels of T throughout the life-course.
Prenatal T surge during prenatal life - development of testes
Declines at birth, postnatal peak
T at nothing during childhood
During puberty testosterone peaks
Levels stable during adulthood and decline but never drop off
List the major functions of male hormones a) in the reproductive tract and b) elsewhere in the body.
In the reproductive tract: stimulates formation of male reproductive ducts, gland, and external genitalia. Promotes descent of testes. Stimulates growth and maturation of the internal and external genitalia at puberty; maintains adult size and function.
In the body: promotes long bone growth, skeletal muscles mass during adolescence. promotes growth of the larynx and vocal cords and deepening of the voice. Enhance sebum discretion, and hair growth.
Where in the uterine tube does fertilisation occur? What does the infundibulum do?
Ampulla
The infundibulum catches newly ovulated oocyte.
How do progesterone and estrogen impact on ciliary
beating in the oviduct?
In the female reproductive system, cilia lining the fallopian tubes play a critical role in the transport of the egg from the ovary to the uterus and in the movement of the fertilized egg (zygote) toward the uterus.
Progesterone is involved in the regulation of these cilia during the menstrual cycle. It may influence ciliary activity in the fallopian tubes, potentially slowing down the movement of the egg, which can be important for successful fertilization and implantation.
Estrogens also play a role in regulating ciliary activity in the fallopian tubes, and their effects can be influenced by the menstrual cycle phase.
Where does sperm maturation occur? What is the critical process required for sperm to become fertile?
Maturation occurs in epididymis
Critical process required for sperm to become fertile if capacitation. It occurs in the female reproductive tract, specifically within the fallopian tubes, and is necessary for sperm to successfully fertilize an egg.
What initiates the acrosome reaction in sperm?
Initiated by sperm contacting the zona pellucida
During fertilisation, what is required to preserve euploidy in the newly formed zygote?
Cortical reaction is required as part of the process that helps preserve euploidy, ensuring the correct number of chromosomes in the newly formed zygote, as opposed to aneuploidy (abnormal chromosome numbers).
Describe the cells within a blastocyst. Which cells will form the fetus? Which cells will form the placenta?
- Trophoblast cell
- Embryoblast or Inner cell mass
Trophoblast cells = Trophectoderm;
will form the placenta
Given the progesterone only pill (POP) has a higher failure rate and lower efficacy than the combined oral contraceptive (COC) pill, why do some women still use it?
Women who have contraindications to
taking estrogen:
* History of hypertension
* History of stroke
* History of thromboembolism (DVT)
What is the main purpose for the withdrawal bleeding that occurs when taking the typical monophasic COC pill?
Withdrawal bleeding is to provide contraceptive efficacy to let women know they are not pregnant and cycle regulation
What are some of the common causes for infertility in males? In
females? What are some of the methods used to assess this?
In males: Reduced semen quality, Vas deferens blockage,
In females: Endocrine abnormalities, ovarian dysfunction, implantation abnormalities, problem with ejaculation reflex, sperm issues
Method used: Assisted Reproductive Technology, IVF (in vitro fertilisation), IntraCytoplasmic Sperm Injection
What are the hormones used in a typical cycle of IVF? What are
their roles in this process? What cells in the ovarian follicles are they acting on?
- Injection of FSH daily for growth of follicles to large antral stage
(monitored by ultrasound); aim for 22-35; <9 = low responder - Injection of LH to induce resumption of meiosis in oocyte (maturation)
and ovulation (typically 36-40 h post-LH) - GnRH agonist – given continuously prior to and during
gonadotropins to suppress natural ovulation - Progesterone also given for luteal support after embryo transfer
Why is ICSI becoming more popular as a method of assisted
reproductive technology to overcome infertility?
Used when male infertility measured
(motility/sperm count) - which is the second most common infertility issue
What are the major differences between spermatogenesis and oogenesis?
Spermatogenesis:
Produces four small, motile sperm per spermatogonium.
Begins at puberty and continues throughout a male’s life.
Both meiotic divisions occur after sperm formation.
Results in a large number of sperm continuously produced.
Sperm are small and have minimal cytoplasm.
Oogenesis:
Produces one large ovum and several polar bodies per oogonium.
Begins before birth and is arrested until puberty.
The first meiotic division occurs during fetal development.
Results in a limited number of eggs, one per menstrual cycle.
Eggs are large and contain abundant cytoplasm and nutrients for early embryonic development.
During in vitro fertilisation (IVF) treatment, a patient receives a daily injection of FSH for 8 to 10 days, followed by an injection of hCG. Cumulus-oocyte complexes are retrieved 35 hours after the
hCG injection from ovarian follicles, just before they ovulate. The patient is subsequently treated with progesterone after oocyte retrieval
Their male partner had a sample of sperm examined, and was found to have sub-optimal sperm motility.
What specific type of IVF would the embryologist recommend for this couple and why?
Intracytoplasmic sperm injection (ICSI)
Where a single sperm is injected into cytoplasm of a mature ovum (egg) to then transfer embryo’s into uterus
During in vitro fertilisation (IVF) treatment, a patient receives a daily injection of FSH for 8 to 10 days, followed by an injection of hCG. Cumulus-oocyte complexes are retrieved 35 hours after the
hCG injection from ovarian follicles, just before they ovulate. The patient is subsequently treated with progesterone after oocyte retrieval
What is the purpose of EACH step in this IVF regime?
Daily Injection of FSH (Follicle-Stimulating Hormone) for 8 to 10 Days:
Purpose: FSH is administered to stimulate the ovaries to produce multiple mature follicles, each containing an oocyte (egg).
Injection of hCG (Human Chorionic Gonadotropin):
Purpose: hCG is given as a “trigger shot” approximately 35 hours before oocyte retrieval. It mimics the surge of luteinizing hormone (LH) that naturally triggers ovulation. It ensures that the eggs within the mature follicles are at the right stage for retrieval and helps with the timing of the procedure.
Retrieval of Cumulus-Oocyte Complexes:
Purpose: This step aims to recover mature eggs for fertilization outside the body. The timing, synchronized with the hCG injection, ensures that the eggs are ready for fertilization.
Treatment with Progesterone After Oocyte Retrieval:
Purpose: After oocyte retrieval, progesterone supplementation is provided. Progesterone prepares the uterine lining (endometrium) for embryo implantation. It supports the development of a receptive endometrium, which is essential for successful embryo implantation and early pregnancy.
FSH affects -
The gonad of both male and female
Spermiogenesis is the process by which
spermatids differentiate into spermatozoa.
State the TWO (2) active components of this pill and describe how they act to prevent the patient from falling pregnant.
Estrogen - Prevents the development and release of a dominant follicle from the ovary, effectively inhibiting ovulation. Additionally, thickens cervical mucus, making it more difficult for sperm to reach the egg, and it alters the endometrial lining, making it less receptive to implantation.
Progesterone - thickens cervical mucus making it hard for sperm to get through
Sperm has been collected from the male reproductive tract and is evaluated for its ability to swim towards the ovum (i.e. its motility). From which location would you retrieve sperm
epididymis
What are THREE (3) common causes of female infertility requiring assisted reproductive technology (ART)?
- Endocrine abnormalities
- Ovarian dysfunction
- Implantation abnormalities
What is it NOT possible to ‘fix’ with ART?
Aged-declined egg quality and aging ovaries
A fertilised egg is called a
zygote
